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Proceedings Volume 0348

15th Intl Congress on High Speed Photography and Photonics

Lincoln L. Endelman
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Proceedings Volume 0348

15th Intl Congress on High Speed Photography and Photonics

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Volume Details

Date Published: 1 March 1983
Contents: 1 Sessions, 176 Papers, 0 Presentations
Conference: 15th International Congress on High Speed Photography and Photonics 1982
Volume Number: 0348

Table of Contents

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Table of Contents

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Advances In High Speed Photography 1972 To 1982
J. S. Courtney-Pratt
The variety, range and precision of methods available for photographic recording of fast phenomena have been increasing steadily. The capabilities of some of the newer techniques will be described. At the lower end of the speed range, the advances have been mainly in improvements in resolution, and in the introduction of video techniques. At the highest speeds the advances have included increases in dynamic range, a wider acceptance of image tubes, and a more careful analysis and characterization of their limitations.
Current And Future Activities In High Speed Photography And Photonics
H. F. Swift
All major specialty areas of the high speed photography and photonics field have experienced rapid development during the past two years and may be expected to continue to do so. ,Intelligent film annotation devices promise to make a major impact upon the applications of pin registered cameras. The advent of color and ultra high speed videography promise other rapid advances. Rotating prism cameras should shortly enjoy advantages of modern film annotation. Top speeds of 16mm reel-to-reel cameras should be extended well beyond 10,000 fps. in the near future. Full use of beryllium as a rotating mirror material for modern cine' and framing cameras is increasing performance capabilities markedly. Emphasis in the development of electronic cameras is shifting toward enhancement of information content of individual records and making cameras more responsive to particular experimental needs. Finally, two new technologies, high speed holography and pulsed laser cinematography show promise of becoming important new technology areas of their own within the near future.
Synchroscan Streak Camera Systems
W. Sibbett
The operating principle and design of synchronous streak camera systems are reviewed and experimental results are included to show that a temporal resolution ~1. ps has been demonstrated. A selection of applications in photophysics and photochemistry are briefly described to illustrate some of the unique features of this diagnostic technique. The further developments relating to an extended range of spectral sensitivity and femtosecond resolution are also briefly discussed.
Picosecond Chronoscopy Of Mode-Locked Semiconductor Diode Lasers For Applications To Ultrarapid Communications And Data Processing
D. J. Bradley
Recent developments in the generation of bandwidth - limited coherent picosecond pulses from mode-locked semiconductor diode lasers are reported. An essential role was played by picosecond electron-optical chronoscopy diagnostics in perfecting these laser systems which have applications to ultra-rapid (Terrabit) real-time optical communications and optical image and data processing. The synchronously driven streak-camera employed in these investigations has been further developed to obtain both picosecond temporal resolution and direct photomultiplier read out from a single image tube. Advantages include reduction in cost, potentially improved S/N ratio, greater dynamic range, increased "free temporal range" and ultimately improved time-resolution in the subpicosecond regime.
Videography Developments
C. E. Miller
A trend is noted toward simpler, less expensive videography systems in those applications wherein their modest frame rate capabilities will suffice. Mechanically-shuttered color cameras, and electronically amplified and shuttered black-and-white cameras provide excellent results with off-the-shelf CCTV components at low cost. Capabilities of the most sophisticated system continue to be expanded, making it a truly quantitative measuring instrument. Extraction of x-y data is simplified and automatically fed to a computer for processing. Software for short-range photogrammetry is being developed. The performance of film and video systems is compared, and a case is made for the development of a videography system having an approximately 720 frame-per-second capability.
Real Time Data Analysis Techniques
George G. Silberberg
By the early 1970s, classical photo-optical range instrumentation technology (as a means of gathering weapons' system performance data) had become a costly and inefficient process. Film costs were increasing due to soaring silver prices. Time required to process, read, and produce optical data was becoming unacceptable as a means of supporting weapon system development programs. NWC investigated the feasibility of utilizing Closed Circuit Television (CCTV) technology as an alternative solution for providing optical data. In 1978 a program entitled Metric Video (measurements from video images) was formulated at the Naval Weapons Center, China Lake, California. The purpose of this program was to provide timely data, to reduce the number of operating personnel, and to lower data acquisition costs. Some of the task elements for this program included a near real-time vector miss-distance system, a weapons scoring system, a velocity measuring system, a time-space position system, and a system to replace film cameras for gathering real-time engineering sequential data. These task elements and the development of special hardware and techniques to achieve real-time data will be discussed briefly in this paper.
The Nature Of Kirlian Photography-An International Overview
Thelma Moss, John Hubacher
After decades of research in the U.S.S.R., Romania, and more recently the United States, it now appears that Kirlian photography may have multiple practical applications in the biological and physicalsciences - particularly as a diagnostic tool in medicine.
High Speed Photomicrography
William G. Hyzer
One of the most challenging areas in applying high-speed photography and videography in the plant and laboratory is in the recording of rapid events at macro and microscopic scales. Depth of field, exposure efficiency, working distance, and required exposure time are all reduced as optical magnification is increased, which severely taxes the skill and ingenuity of workers interested in recording any fast moving phenomena through the microscope or with magnifying lenses. This paper defines the problems inherent in photographing within macro and microscopic ranges and offers a systematic approach to optimizing the selection of equipment and choice of applicable techniques.
High Speed Photography In The Federal Republic Of Germany
Manfred Hugenschmidt
The present paper gives a survey on recent applications of high-speed photography and cinematography in various fields of scientific research such as plasma physics, laser physics and high power pulse technology. Toward this end classical optical systems have been used and new recording methods have been developed. Improved temporal and spatial resolution has been achieved. High-speed shutters provide useful information if self-luminous phenomena have to be in-vestigated. Since high light amplification is obtained with intensifiers even weakly luminous processes such as electrical prebreakdown phenomena can be recorded. The use of lasers provides highly interesting applications in the ps-, ns- and in the ps-time scale. New laser switching techniques are reported. Nano- and subnanosecond laser pulses, like those produced by superradiant gas laser sources are currently used, because pulse repetition rates up to the GHz range are easily available. By the use of additional dyes the wavelengths of these pulses can be transformed nearly throughout the whole visible spectral range. If needed for particular experiments, precise timing can be provided. For highest time resolution, however, mode locked lasers are required. Examples are given of the feasability of high-speed photographic techniques for the investigation of electrical discharges, for example in sparks or in plasma focus devices, and for studies of optically induced breakdown processes by focussing high power laser radiation on solids state targets, liquids or gases.
Exposure Time: It Can Be Important
Harold E. Edgerton
All electronic flash sources have "fast," that is, "short" exposure times compared to conventional shutters. There are many users who do not realize that the effective exposure time is not the same for all flash equipments. This paper discusses the exposure time and how it is influenced by the electrical characteristics of the flash lamp, and the electrical discharge circuit. It is pointed out that the "exposure time" of many electronic flash lamps is entirely too long for some applications. The "blur" experienced in a photograph of each subject is directly due to the exposure time, and the velocity of the subject. It is obvious that photographs of people do not require as short an exposure as does the photography of a fast moving bullet. Most of the imporant factors influencing the flash-duration of electronic flash lamps will be discussed in detail. Specialized equipment for bullet and bird photography, where extra short exposure times are important, will also be described.
New Trends In Picosecond Photonics
M. Ya. Schelev
Currently topical problems connected with the further development of image-converter streak tube diagnostics aimed to overcome the 1 ps temporal resolution limit are discussed. In this connection some approaches in streak tube designing are treated and some evidence of 0.1 ps temporal resolution achievement are given. The very promising possibility of recording 1.468jKm and 2.94/Km radiation with picosecond temporal resolution is clearly demonstrated. Measurements of KCl and NaCl semiconductor detectors intended for soft X-ray radiation recording offer further temporal resolution spreading into the subpicosecond region for X-ray streak tubes. Reliable radiation sources capable of providing ultrashort pulses in the visible (0.6./Km) and infrared (1.06; 1.468; 2.94/t m) spectral regions are briefly mentioned. Finally the need to design up-to-date Electron-Optical Measuring Systems (EOMS) consisting of modern image-converter cameras, read-out devices and picosecond lasers is particularly emphasized.
"Zea"-Because It's There
Eric Chamberlain
The Subject is a long standing symbiotic relationship between Zea and the movies. As usual the impossible was required - to attain cinema release quality films with dramatic interpretation - at the same time using Hy-speed macro photographic techniques. The subject was not to be recognizable until the end of the film - some four minutes long. Zea is explosive, it reacts to heat and is extremely difficult to predict when it will explode, which left little time for the focus, stop down and shooting. Using a Hy-cam at 5,000 pictures per second - a 400 ft. roll of 7247 raw stock, left but a brief three seconds for synchronization. To add to the confusion, two co-directors, a cameraman, plus equipment, were jammed into a 2 x 2m space. To achieve reasonable resolution for theatrical showing, 400,000 foot/candles of light were needed. This was achieved. The film was edited and music from Vaughan Williams' "Fantasia" recorded at St. Martins-in-the-Fields, London was added. The result was sent to the Cannes Film Festival, where it was given the Jury Award.
Observational Study On Thermal Flow And Condensation Of Injecting Steam From Various Submerged Orifices
Shuya Kamei, Masaru Hirata
It has been recognized that the steam accumulator plays an important role as one of thermal energy storage system and was used at hospitals, hotels and food factories in recent years. Experiments have been carried out to investigate direct contact condensation of saturated steam into a quiescent subcooled water environment. They were performed for subcooling from 20 - 70°C, for atmospheric pressure, and for various type of orifice ( single-orifice, multi-orifice and porous-disc-orifice ). The phenomena were observed by means of high speed shadowgraphy using a rotating prism camera. The phenomena were also visualized by techniques of liquid crystal using a still camera. The effect of bulk temperature in a water tank and the difference among a single-orifice, a multi-orifice and porous-disc-orifice were discussed and good predictive results for the visualization of thermal flow in a quiescent subcooled water environment were obtained.
Behavior Of A Fast Projectile Shot Into Water
Shoji Kageyama, Tositika Usui
Investigations carried out on the high speed entry of spinning cylindrical projectiles are described. The projectiles mainly used were 30°, 60°, 90° conical nose cylinders and flat-nosed truncated cone cylinders. Their specific gravities were from 2.69 to 11.34. To study behaviors of the projectiles, high-speed stereoscopic motion pictures were taken of numerous shot of each of the projectiles at various impact speeds from about 250 to 1000 m/s. Time and position data of the projectiles were read from each film, and using our method of data processing instantaneous position of the projectiles were accurately determined. By comparing each shot of a dense projectile with each suitable shot of a light one, we try to determine the added mass for each projectile shape, but no decided values of them were obtained.
Utilizing High Speed Film In Metal Cutting Research
Jan Liptak
The paper emphasizes the necessity to search for new methods and criteria in the eveluation of metal machinability from physical positions. It points out the possibility to evaluate machinability according to motional characteristics of the cutting zone. It describes methods and results of author's study with the use of cinematographic methods of recording the phenomena in the cutting zone. It gives a brief outline of high speed sicroscopic recording of the microelements motion in the cutting zone and it suggests some methods and approaches to a computer processing of the data obtained experimentally.
An Optical Challenge
Richard Oyama
"We are going to blow up your cameras -- how are you going to get the data?" The purpose of this test was to obtain sufficient data on displacement-time histories of the inner wall of a cylinder 3 inches thick, 45 inches in diameter, and 70 inches long. Three quarters of the cylinder upper, outer wall surface was completely encircled by high explosive. The explosive quantity had been calculated to be 700 pounds. During detonation high-speed cameras were to record the motion of the inner walls during closure. The camera was approximately 20 feet from the cylinder. The total event was less than 2 milliseconds. The photographic system for gathering data had to be right the first time -- there would be no second chance. Many design and photographic problems were encountered in developing a recording system for this particular testing: 1. Limited opening for camera viewing 2. Mirror and cameras (detonation shock effects on mirror and cameras) 3. Alignment of mirror and cameras 4. Lighting 5. Sequencing the cameras and event 6. Remote area (no power available) 7. The specimen was to be buried by 145 cubic yards of sand. The Photo Instrumentation Unit at Lockheed Santa Cruz Facility has successfully met this challenge. It is my purpose here to present records and to define the camera systems and the problems that were encountered during this photographic assignment. I will not define the prime purpose nor the final results of this test, since the test purpose is irrelevant in this context.
Applications Of Flow Visualization Techniques In Aerodynamics
Claude M. Veret
The optical techniques keep a large interest in aerodynamics to visualize the flow in wind tunnels. Beside the fact they are non intrusive, these techniques provide a global view of a large field in the flow which, even if purely quantitatively, helps the aerodynamicist to interpret local measurements performed by a limited number of probes like Pitottubes, hot wires and so on. In this presentation, we intend to show new applications of well known opticals techniques improved by the use of laser light. The first one concernes the holographic interferometry used in the millisecond to microsecond domain to analyse the turbulence in a boundary layer. The second one will show visualization of smoke seeded flows illuminated by a light sheet provided by a laser beam enlarged, in one dimension, by a cylindric lens. This is applied to the study of vortices in the microsecond to nanosecond domain, illustrated by slides and film.
Perfect Optical Compensator With 1:1 Shutter Ratio Used For High Speed Camera
Rong Zhihong
An optical compensator used for high speed camera is described. The method of compensation, the analysis of the imaging quality and the result of experiment are introduced. The compensator consists of pairs of parallel mirrors. It can perform perfect compensation even at 1:1 shutter ratio. Using this compensator a high speed camera can be operated with no shutter and can obtain the same image sharpness as that of the intermittent camera. The advantages of this compensator are summarized as follows: . While compensating, the aberration correction of the objective would not be damaged. . There is no displacement and defocussing between the scanning image and the film in frame center during compensation. Increasing the exposure angle doesn't reduce the resolving power. . The compensator can also be used in the projector in place of the intermittent mechanism to practise continuous (non-intermittent) projection without shutter.
Construction And Evaluation Of A Simple And Inexpensive Rotating Prism Camera For Recording The Movement Of Shocks And Particle Tracers Within A Shock Tube
David K. Walker, Lawrence N. Scotten, John M. Dewey
A simple, inexpensive rotating prism camera constructed from readily available materials using standard machining techniques has been constructed. The camera can record up to 100 pictures on 35 mm format at a rate of 50,000 per second. A pulsed ruby laser is used as a light source giving exposure times of approximately 50 nanoseconds. The performance of this camera in recording the movement of shock waves and particle tracers in a shock tube is described.
Impact Loading Of Notched Bars
R. S. J. Corran, R. A.W. Mines, C. Ruiz
Three types of notched bar impact tests are often used for the assessment of the notch toughness of materials: the Charpy, Izod and the circularly grooved bar. Photoelastic analysis with low-modulus models and 8,000 f.p.s. photography permits the study of these tests with a view to quantitative interpretation of the results in terms of fracture toughness parameters
New Rotating Prism Drum Camera
W. Hochtl, W. Wittwer
The car industry is using high speed photography for crash testing and other dynamic testing of components. For this purpose high speed cameras with frame rates between 400 and 1000 frames per second are being used, whereas the time period to be measured is in the range of about 100 - 250 ms.
Speed Control For A High Speed Motion Picture Camera
George J. Thaler
Motion picture cameras exist which take pictures at frame rates as high as 10,000 frames/second. Their development has been accomplished largely by invention, trial and error, and much hard work. They work very well, but the demands of scientific research require that frame rate be closely controlled so that accurate time measurements can be made when analyzing the photographic records. The purposes of this paper are to establish a mathematical model of the film transport system and to study the dynamics of the system.
Real Time Track Studies At Centre D'essais Des Landes (CEL): The Sled Track As A Test Facility At Cel
J. C . Miguel
The Centre d'Essais des Landes is equipped with a sled track for testing materials under dynamic conditions. We shall present a film showing various types of observations and measurements using film techniques. This film shows the testing of an ejection seat from the cockpit of a Mirage 2000 aircraft. The actual duration of the test is 10 to 12 seconds. The different sequences of the film are - Continuous tracking with rotating servo mirror (MARS) of the mock up of the cockpit at a speed of 128 meters per second. - In-board cameras. - Cameras fixed on the top and on both sides. - Hand tracking camera.
Simplified Streak/Strip And Scanning Photographic Systems
Andrew Davidhazy
While streak cameras in particular, and strip cameras to an almost equal extent, are widely used in high speed photography, the level of sophistication achieved by these systems makes them appear much more complex than they really are. In this presentation the principles of slit shutter and scanning photographic techniques are related to ordinary focal plane shutter operation parameters. The commonalities and similarities between high speed and low speed systems are presented in very basic fashion. Photofinish, velocity recording, panoramic, peripheral and perspectiveless photography are among the applications explained and illustrated. Basic equipment suitable for experimentation is also described.
Precision Drilling Of Sugar Beet
Jaroslav Kalina
The paper describes the features of the precision drilling of sugar beet, methods of measurements, mathematical relations, procedure and results. The use of a high-speed camera and of a computer with an investigation of the drilling mechanisms enabled to achieve the shortening of the procedure by one half, an accurate assessment of the principles of drilling mechanisms without implication of other influences arising in field tests and the availability of more data for decision making. The result of the experiments was a considerably simpler assessment of the principles of drill mechanisms.
System For Determining The Velocities Of Individual Fragments From An Exploding Warhead Using High Speed Photography
Donald Hollingworth, Hendrik J. van der Merwe
When a fragmentation warhead explodes, fragments are hurled outwards in all directions and in effect become projectiles with a capacity for inflicting damage on nearby objects. For kinetic energy calculations it is necessary to know both the mass and velocity of the fragments. These velocities can most easily be ascertained by the use of high speed photography. Owing to the considerable difference in speed between the fastest and slowest fragments emanating from an exploding warhead, a high speed motion picture camera, framing at the rate of 10 000 pictures per second, has been found to be a good medium for measuring their velocities. For instance velocity measurement tests have shown that over a distance of five metres from the centre of the warhead to the edges of the velocity plates, the difference in speed between the fastest and slowest fragments from an exploding 460 kg warhead covers a time span of at least 1 millisecond. This would represent 10 frames on a film running at the rate of 10 000 pictures per second. This paper will set forth the operating principles of the high speed photographic measuring techniques and the degree of accuracy which can be expected from it. Throughout the text the term warhead has been used to describe any fragmenting high explosive shell, bomb, rocket warhead, grenade or other explosive munitions.
High Speed Photographic Studies Of Rocket Engine Combustion
Tsuneyoshi Uyemura, Shigeo Ozono, Toshio Mizunuma, et al.
The high speed cameras were used to develop the new sounding rocket motor and to check the safety operation system. The new rocket motor was designed as a single stage rocket and its power was greater than the multi-stage K-9M rocket motor. The test combustion of this new type rocket engine was photographed by the high speed cameras to analyze the burning process. At the outside of rocket chamber, the cable which connect the detector of an engine nozzle with the telemeter system was fixed. To check the thero.,a1 influences of combustion flame to the cable, the thermo-tapes and high speed cameras were used Safety operation system was tested and photographed with high speed cameras using a S0-1510 model rocket.
Electro-Mechanical Chopper For Standard Light Pulse Generation
Serge Prohoroff
Absolute intensity calibration of the transfer function of a photodetector measuring line is not a straightforward technique. One of the many hints is that it depends on almost all parameters of the experimental set-up. All stable and reliable light standards are continuous working, and thus low level devices. Pulsed sources do exist, but are neither traceable nor calibrated and give badly reproducible pulses. The device which is presented here makes it possible to use standard CW sources, with exposure time down to a few microseconds. The main idea on which the device is based, is to use the multiplication factor of the angular speed of a optical ray reflected by a rotating mirror. Starting at a usual speed wl, a chain of n mirrors gives a final speed 2nw1 . The procedure is well suited to all detectors including photoemulsions, however less accurate in this latter case.
Application Of High Speed Photography In Science And Technology
Wu Wu Ji-Zong, Lin Yu-Ju
The service works in high-speed photography carried out by the Department of Precision Instruments, Tianjin University are described in this paper. A compensation type high-speed camera was used in these works. The photographic methods adopted and better results achieved in the studies of several technical fields, such as velocity field of flow of overflow surface of high dam, combustion process of internal combustion engine, metal cutting, electrical are welding, experiment of piling of steel tube piles for supporting the marine platforms and characteristics of motion of wrist watch escape mechanism and so on are illustrated in more detail. As the extension of human visual organs and for increasing the abi-lities of observing and studying the high-speed processes, high-speed photography plays a very important role. In order to promote the application and development on high-speed photography, we have carried out the consultative and service works inside and outside Tianjin Uni-versity. The Pentazet 35 compensation type high-speed camera, made in East Germany, was used to record the high-speed events in various kinds of technical investigations and necessary results have been ob-tained. 1. Measurement of flow velocity on the overflow surface of high dam. In the design of a key water control project with high head, it is extremely necessary to determinate various characteristics of flow velocity field on the overflow surface of high dam. Since the water flow on the surface of high overflow dam possesses the features of large flow velocity and shallow water depth, therefore it is difficult to use the conventional current meters such as pilot tube, miniature cur-rent meter or electrical measuring methods of non-electrical quantities for studying this problem. Adopting the high-speed photographic method to study analogously the characteristics of flow velocity field on the overflow surface of high dam is a kind of new measuring method. People
Ultrafast Gating Of Proximity Focused Microchannel-Plate Intensifiers
Arvid S. Lundy, A. Evan Iverson
Proximity-focused, microchannel-plate (MCP) image intensifiers have been used at Los Alamos for many years to allow single frame film and video exposure times in the range of 2.5 to 10 ns. There is now a program to reduce gating times to <1 ns. This paper reviews previous work and the problems in achieving good resolution with gating times of <1 ns. The key problems involve applying fast electrical gating signals to the tube elements. We present computer modeling studies of the combined tube, tube connection, and pulser system and show that low photocathode surface resistivity must be obtained to permit fast gating between the photocathode and the MCP input. We discuss ways of making low-resistivity S20 photocathodes, using gallium arsenide photocathodes, and various means of gating the tubes. A variety of pulser designs are being experimentally evaluated including spark gaps, avalanche transistors, Krytron tubes with sharpening gaps, step recovery diodes, and photoconductive elements (PCEs). The results of these studies are presented. Because of the high capacitances involved in most gating schemes, the tube connection geometry must be of low-impedance design, and our solution is presented. Finally, ways of testing these high-speed camera systems are discussed.
Open Grid Versus Mesh Grid As The Extraction Field Structure In A Streak Camera Image-Converter Tube
S. W. Thomas, R. L. Peterson
We conclude that dynamic range of a streak tube does not depend on whether it uses a fine-mesh or an "open" structure to provide the extraction field. An RCA C-73435 streak tube body was fitted with two extraction grid structures by replacing the conventional "open" grid with a steel plate containing two apertures. One aperture simulated the "open" grid structure; the other was a 2 x 20 mm slit covered with a fine mesh (40 wires per mm, 38% transmissive). The apertures were equal distances above and below the tube axis. Using 35-ps pulses, dynamic range curves were taken at 1.06 pm on one aperture at a time, while blocking the other aperture. As we anticipated, the tube saturated at nearly the same point for the open and mesh apertures. The noise levels for both apertures were almost equal and very close to the film fog level. Noise level was lower than for earlier measurements on other makes of tubes with a fine-mesh grid. The dynamic range for both apertures was in the order of 6000, which indicates that the lower dynamic range of otner tubes must be due to something other than the use of a fine-mesh grid.
Space-Charge Perturbation Effects In Photonic Tubes Under High Irradiation
R. Kalibjian, G. G. Peterson
Potential perturbation effects at the cathode region of a photonic tube can occur at high intensity due to space-charge. Using appropriate photoelectron energy distribution functions, the electric field at the cathode is calculated and its effect upon the spatial/temporal resolution is examined.
Recent Developments In The Dissector/Restorer Framing Camera Tube
R. Kalibjian, S. Thomas, J. P. Henz, et al.
The dissector/restorer framing camera tube (DRFCT) has been characterized with a Nd:YAG mode-locked laser. The 3-frame format tube has a 0.5 x 0.5 cm field-of-view (referenced to the photocathode) and 0.3 ns duration frames with better than 5 1p/mm spatial resolution (at cathode) using a microwave triode tube driver.*
Dynamic Tests And Application Of The Electron-Optical Measuring System
T. Hiruma, H. Ilida, E. Inuzuka, et al.
The basic and dynamic performances of the new Electron-Optical measuring system type EWE in conjunction with various laser applications are presented. The system consists of Electron-Optical streak camera which is sensitive in the spectral recion from 380 nm to 1100 nm, TV read-out device and microprocessor controlled frame memory. Main features of the developed system will be described. The limiting temporal resolution has been measured to be 1.4 ps at FWEM. The dynamic range Of 70 at the measured duration of 5 ps has been obtained.
Dynamic Performances And Applications Of A New Two Picosecond Streak Camera System
E. Inuzuka, Y. Tsuchiya, M. Koishi, et al.
The dynamic measurements of a new 2 picosecond (ps) streak camera combined with a silicon intensifier target (SIT) TV. camera and a microprocessor based multi-window Temporalanalyzer (MWTA) have been carried out with the help of several types of picosecond lasers. Limiting temporal resolution has been measured to be 1.67 picosecond at FWHM using 0.75 ps pulses from the passively mode-locked dye laser excited by an Ar+-ion laser. Intensity dependent temporal resolution has also been measured with the 4±1 ps laser pulse from the mode-locked Nd:Glass laser to define the dynamic range in various streak ranges. Direct observation of the fine structure in the light pulses emitted from a laser diode has shown a good application of the 2 ps streak camera system.
Internally Intensified Photochron II Streak Tube
W. Sibbett, W. E . Sleat, J. R. Taylor, et al.
The salient design features of a version of the Photochron II streak tube having an internal microchannel plate intensification stage are described. Experimental results are presented to demonstrate that a streak camera incorporating this image tube has a temporal resolution ~1 ps it the synchroscan mode of operation and ~4 ps in single-shot operation.
New Streak Tube Without Time-Dispersion Slit Image Curvature
Katsuyuki Kinoshita, Nobuyuki Hirai, Yutaka Tsuchiya
A new streak tube without the curvature in a time-dispersion slit image at various streak speed has been developed. It has a concave photocathode which equalizes the transit time of photoelectrons emitted from different positions on the photocathode. The results of the computer simulation, such as the optimum curvature of tkie photocathode, were applied to the design of the tube. Experimental result shows that the new tube produces straight slit images up to the streak speed of ~108m/s where the time resoluiton of ~2ps is obtained.
Development Of A New Synchroscan Tube Incorporating A Microchannel Plate
Katsuyuki Kinoshita, Kazunori Shinoda, Yoshiji Suzuki
In the development of synchroscan tube operated over wide sweeping frequency, multi-pactor discharge which increases back ground noise of the tube, has been investigated in detail. It has been found that the problem of discharge can be solved mainly by suppressing the secondary electron emission from the electrodes in the deflecting section in the tube. On this result, a new synchroscan tube has been developed. This tube can be operated over wide sweeping frequency from 80MHz to 160MHz and the limiting time resolution of the tube itself of about 8ps has been obtained at 80MHz. Driving the tube in synchroscan mode is very easy because the tube has high deflection sensitivity, 50mm/kVp-p. Moreover, this tube incorporating a microchannel plate(MCP) is very high sensitive, by adding the effect of synchroscan mode.
Picosecond Streak Image Tube With Curved Photocathode And Mesh
H. Niu
A special designed picosecond streak image tube with curved photocathode and curved mesh has been described. Besides high temporal resolution as other reported tubes, it has eliminated the temporal distortion which was serious in other ones. Because of the utilization of curved photocathode and curved mesh, the temporal dispersion and the geometrical aberrations have also been improved compared with the tubes with flat photocathode and flat mesh. Its characteristics have been evaluated by means of the spatial and temporal modulation transfer functions.
Photochron III: A New Image Tube Design For Subpicosecond Streak Operation And Picosecond Framing
D. J. Bradley, K. W. Jones
A new electron-optical image tube (the Photochron III) has been designed to achieve a time-resolution of 200 fs or less with high spatial and temporal resolutions over an extended field. Use for an ultra-rapid framing camera is also indicated. In both cases the dynamic range should be improved because of the high mean axial potential voltage employed in the electron-optical arrangement.
Synchroscan Streak Camera
Y. Tsuchiya, A. Takeshima, E. Inuzuka
A, new synchroscan streak camera which operates at a repetition. rate of 80 to 160 MHz in synchronism with a repetitive pulse laser is described. It employs a newly developed streak tube incorporating a microchannel plate as an image intensifire. Dynamic performances were investigated. by using a passively mode-locked cw dye laser and a direct readout system. Experimental results show that thi,e synchroscan streak camera combined with the direct read-out system at present has a overall temporal resolution of 11 ps for a integration of % 106 pulses and a dynamic range of better than 1:200. In addition, results of fundamental study indicate the strong possibility of achieving the dynamic range of 0, 1:106 by improving the readout system. An application of the streak camera in direct measurement of relaxation oscillation of a sinusoidally modulated diode laser at 133 MHz is also included.
Programmable Image Converter Framing Camera
Alex E. Huston
New techniques for the operation of electrostatically focussed and deflected image converter tubes in the framing mode have been developed. Solid-state devices are used throughout. The camera may be programmed to provide various numbers of frames, each exposure duration, and each frame interval, being individually adjustable. A separate programming unit permits the operator to preset the required sequence, the appropriate data being transferred to a fast-access memory in the camera. Triggering of the camera then initiates the stored sequence.
High Speed Photography To Provide A Three-Dimensional View
J. S. Courtney-Pratt
A method is described for obtaining a 3-Dimensional record of a distant object or scene from a single viewpoint. The object or scene is illuminated by a brief flash of light, and a fast sequence of 2-Dimensional pictures recorded by the (diffusely) reflected light. In a typical case, the scene might well be a kilometer distant, the light flash might last 10-9 s and the sequence of pictures comprise, say, 100 frames at intervals of 10-9 s. The depth resolution would then be 15 cm in a total depth of 15 m and the lateral dimensions and resolutions could be similar.[1] Suppose we illuminate an object with a brief flash of light. If the flash is intense enough, we could take a photograph by the light reflected from the object. The light reflected from the nearest part of the object reaches the camera before the light from more distant points. So, if the camera has a fine enough time resolution, we could take a sequence of pictures which would record the varying time of arrival of the light, and so have a 3-dimensional record rather than the usual photographic 2-dimensional record. H. J. Caulfield and S. Somerstein[2] have suggested a somewhat similar scheme but considering only a line image across an object rather than aiming to make a full 3-D record. Several interrelated questions arise. What kind of camera? What lateral and depth resolutions? How bright a flash? Of mechanical cameras, the rotating mirror raster camera[3,4] has the finest time resolution, about 10-9 s.[5,6] Light travels 30 cm in 10-9 s, so that the depth resolution could be 15 cm. In clear still air the best angular resolution is about one second of arc. Let us consider a lateral resolution equal to the depth resolution, 15 cm. The distance R at which 15 cm subtends one second of arc is 30 km. As shown in Appendix I, the flash intensity that we would need would be about 100 joules - not at all an impossible figure with a Q-switched laser that would give a pulse of nanosecond duration - or at least a pulse with a rise-time of about a nanosecond. At shorter ranges and the same angular subtense the flash energy could be much less. Alternatively, at a range of 1 km and the same object size (15 m) and resolution (15 cm) as above the required flash energy is as before about 100 joules; and the diameter of the camera lens can be much smaller. Similar calculations can be made for dissecting image converter tube (ICT) cameras[?-10], where the time resolution can be a few picoseconds (or less)[11-13] and the corresponding depth resolution can be about a millimeter. See Appendix II. For equal lateral and depth resolution of 1 mm and with a 10 cm object the range can be 200 m. With a 20x slower sweep in the ICT, depth resolution would be 2 cm and with equal lateral resolutions of 2 cm in a 2 m object, the range could approach 4 km. Such resolutions might well be useful, particularly if one could not physically approach the object under study. The time-resolved record gives a depth resolution many times better than could be achieved at such distances with conventional coincidence-type range finders.
High Resolution Nanosecond Gated Image Intensifier Diode
W. Pfeiffer, D. Wittmer
The temporally and spatially resolved investigation of ultraviolet, visible and infrared radiation is possible by use of image intensifiers. Today many of these are of the proximity focus type. The PROXIFIER is such a diode with a very high electric field and it shall be considered in this contribution. The very high electric field strength results in an output image with negligible distortion and very high resolution. If necessary, the gain can be increased by cascading several diodes. With a three stage cascade the same gain can be achieved as with an image intensifier tube using a microchannel-plate. The gain uniformity and especially the resolution of such an image intensifier cascade, however, are much better. For the analysis of transient radiating phenomena the PROXIFIER can be gated with very high speed. This gating is achieved by switching the operating voltage of about 9 kV. The limiting aperture time presently is about 2 ns. Even for shutter times below 10 ns the limiting resolution is better than 20 linepairs per millimeter. The performance is greatly de-pendent upon the efficiency of the high-voltage pulse generator and the image intensifier housing. The generator can be triggered with low time lag and negligible jitter. This is achieved by use of a 30-stage transistor cascade. In order to get pulses of very short duration, a pulse forming network is used. In this case the pulse half width can be below 5 nanoseconds. Due to the non-linear gain characteristics of the diode, which is strongly dependent upon the operating voltage, the effective shutter time is still smaller than the pulse half width. The shortest shutter times which are possible today are about 2 nano-seconds. Presently the gated image intensifier is used for the measurement of breakdown development in compressed gases and short time spectroscopy.
Picosecond Framing Image Tube
W. Sibbett, M. R. Baggs, H. Niu
The general features of the configuration and operating principle of a new framing image tube which has been designed to give picosecond resolution are described. Theoretically predicted performance characteristics are presented which indicate that a temporal resolution ~100 ps and a spatial resolution %10 1p/mm should be attainable in a multiple-framing mode of operation.
Femtosecond Streak Image Tube
W. Sibbett, H. Niu, M. R. Baggs
Some design features and performance characteristics of a Photochron IV femtosecond streak image tube are presented. A more compact miniaturised version of the tube is also described and results from a preliminary theoretical evaluation of its performance are discussed.
Design Of Neutron Streak Camera For Fusion Diagnostics
C. L. Wang, R. Kalibjian, M. S. Singh
The D-T burn time for advanced laser-fusion targets is calculated to be very short, < 50 ps. We describe the design of a neutron streak camera of 16 ps resolving time that can be used to study the temporal history of fusion burn. The cathode of the neutron streak camera is sensitive to neutrons and is curved such that the difference in the neutron path lengths from a point source to various parts of the cathode is compensated by electron transit times within the streak tube. Thus the cathode can be made large for high sensitivity, without sacrificing time resolution. The cathode is coated with 1 pm UO2. Each fission fragment leaving the cathode generates 400 secondary electrons that are all < 20 eV. These electrons are focussed to a point with an extractor and an anode, and are then purified with an electrostatic deflector. The electron beam is streaked and detected with the standard streak camera techniques. Careful shielding is needed for x-rays from the fusion target and general background. It appears that the neutron streak camera can be a viable and unique tool for studying temporal history of fusion burns in D-T plasmas of a few key ion temperature.A;
Instrument For Simultaneously Measuring Intensity, Time, And Wavelength: The Temporal Spectral Photometer
N. H. Schiller, R. R. Alfano
The design, performance and characteristics of a compact instrument for measuring the intensity as a function of time and wavelength emitted from luminous events is described. The instrument enables the user to display luminous kinetics on a picosecond time scale over a wide spectral range from 200 to 850nm. To demonstrate the instrument's capabilities, data will be presented on the temporal and spectral profiles emitted from photo excited dyes.
Recording Of Subpicosecond Pulses In Neodymium- And Dye-Laser Radiation
O. M. Brekhov, V. B. Lebedev, V. B. Luzanov, et al.
For the first time the subpicosecond pulses in the radiation of the neodymium laser and in the dye superfluorescence were recorded by a direct method of electron-optical chronography.
ZMF-2 Image-Converter Tube With Grid Shutter
G. I. Bryukhnevich, E. I. Zak, V. G. Kucherov, et al.
Image converters (IC) in which the electron image is focussed in uniform electric and magnetic fields can be constructed with a large active field of the photocathode, high spa-tial resolution over the whole active field, and. little geometric distortion. A. grid elect-rale positioned, near the photocathode, parallel to the cathode surface makes it possible to construct IC with a control electrode (shutter). In the USSR. this type of IC called ZMF-2 has been developed and produced.
Effect Of Wavefront Curvature On The Duration And Shape Of Subpicosecond Laser Pulses Recorded By An Image-Converter Tube
G. V. Kolesov, I. M. Korzhenevich, V. B. Lebedev, et al.
When subpicosecond laser pulses are recorded, allowing for their distortions by the input optical system becomes important. Previous studies were concerned with the pulse pulling caused by aberrations (1) and by the dispersion of the glass refractive index (2). The present paper analyzes the phenomena associated with the non-isochronism of the image construction on the IC photocathode, namely, the pulling of the pulse, the distortion of its shape in the case of a circular aperture (in the circular or spiral sweep regime) and the distortion of the image on the IC screen for a slit aperture (in the linear sweep regime). The non-isochronism arises because of the curvature of the laser beam wave front (WF) in the photocathode region (3).
Effect Of The Axial Potential, Photoelectron Distribution, And Form Of Spot On The Screen Upon The Transfer Function Of A Time-Analyzer Image-Converter Tube
V. S. Bulighin, E. I. Galynker, Yu. A. Drozhbin, et al.
The transfer function of an ICT which analyzes the time structure of a high-speed process (1) and recognizes the signal delay in the photocathode and electron optical and scanning systems of the EOC is written in the form
Investigation Of Peculiarities Of Image Formation In An Electron-Optical Photochronograph With Subpicosecond Time Resolution
G. I. Bryukhnevich, G. V. Kolesov, I. M. Korshenevich, et al.
According to the results of studies of processes that occur on subpicosecond scale by the electron-optical photochronogra2hic cameras (1), for processes recorded with the linear sweep velocity above (1-2)1010 cm/s the deciphering of photochronograms must take into account the specific distortions of the image that arise because of the non-isochronism of the image converter (IC) electron-optical system.
Shape Distortion Of A Current Pulse In The Image-Converter Tube Due To Coulomb Repulsion
V. S. Bulighin
Assume that an electron cloud generated by current with jo(r) density emanates from a photocathode to form a flat disc whose thickness is negligible in comparison with the diameter. Then the stratum of photoelectrons which emanate at the time T moves in compliance with the equation
Harmonic Contrast-Temporal Characteristics Of Sweep Systems And Electron Optics Of Time-Analyzing Image-Converter Tubes
V. S. Bulighin, Yu. A. Drozhbin, B. M. Stepanov
The most descriptive metrological characteristic of a time analyzing image-converter tubes (ICT) is its transfer function, which is the relationship between the light energy as shown by the phosphor in the ICT display and the instantaneous power of input radiation. Because of the difficulties in direct experimental determination of a high speed ICT transfer function the time resolution has to be ranked in different ways. One of these is to determine the time ICT resolution by using contrast temporal characteristics (CTC) (1, 2, 3). The ICT photocathode receives a standard signal whose temporal variations are characterized in terms of the parameter T. The CTC represents the dependence of the contrast 6 on the ICT screen on T.
Computer Simulation Of Electrodynamic Processes In High Speed Image-Converter Tubes
B. I. Beilin, E. I. Galynker, E. V. Panasyk, et al.
The time resolution of today's image-converter tubes (ICT) is only an order of magnitude higher than the theoretically estimated limit*. The processes inside the instrument are not easily calculated in such cases. This is true of the experimentally observed effect of charge pattern variation due to current take off from the photocathode and mutual repulsion of electrons during the transit.
Light Intensifier Application In Time Resolved Spectral Analysis
Serge Prohoroff
When investigating the whole range of visible spectra with time resolving devices, same performances as transfer function, bandwidth, resolving power, are but seldom simultaneously achieved. A light intensifier inserted between the dispersed light source and the detector array may improve in many respects the features of the optical analyser.
Jitter-Free Signal Averaging Streak Camera
Wayne Knox
A streak camera with 2 ps shot-to-shot jitter and zero drift in timing has been developed. A picosecond high power switch which is DC-biased and operated at room temperature is used. In this article, we discuss recent sweep modeling and measurement results and some applications in picosecond fluorescence kinetics experiments.
Picosecond Electron Diffraction
Steve Williamson, Gerard Mourou, Samuel Letzring
Electron diffraction on the picosecond time scale is demonstrated using a picosecond photoelectron burst generated by an optical pulse incident on the front end of a streak camera. Because of the picosecond synchronization between the optical and electron pulses, this technique makes possible the study of laser-induced structural kinetics in the picosecond time domain.
Time Resolved X-Ray Spectrometry For Laser Fusion Studies
R. S. Marjoribanks, S. A. Letzring, M. C. Richardson, et al.
Study of the spectrally and temporally resolved emission of x-rays from laser-irradiated targets can provide information on the absorption of laser energy and its transport in the target, and on the general hydrodynamics of imploding target shells. In this paper we describe the 14 channel streak spectrometer in use at the Laboratory for Laser Energetics, University of Rochester and relate its use in investigating laser-matter interaction at λ=0.35 μm and 1.054 μm. In addition to a description of the 14 channel, CsI-Au bifurcated photocathode device, we describe its novel use in providing an absolute laser (λ=0.35 μm) fiducial from light scattered specularly from planar targets; its use in symmetrically imploded targets (λ=1.054 μm); its use in investigations of thermal transport; and a novel use of the differentially comparing densitometer to remove film characteristics.
Time Resolved X-Ray Spectroscopy Of Symmetrically Imploded Targets
S. A. Letzring, R. S. Marjoribanks, M. C. Richardson, et al.
Time resolved spectroscopy has been used to examine the history of x-ray emission from a variety of spherical targets symmetrically and directly imploded using the 24 beam OMEGA laser system. In this paper, we describe recent results obtained using an x-ray transmission grating-streak spectrograph and a filter foil streak spectrometer, which analyze the line and continuum x-ray radiation from imploding gas-filled spherical shell targets. The time history of this emission in conjunction with data from other spectrally and spatially resolving instruments can then be used to aid the understanding of the implosion physics.
Picotron 100 Streak Tubes As A 150 Channel Photometer
S. Majumdar, P. B. Weiss, J. P. Black
The characterization of a streak camera based upon Picotron 100 tube types1'2 is given. Both a large (30 cm 1 x 10 cm dia.) and a small (18 cm 1 x 5 cm dia.) version of this design has been tested. Over 150 channels of information are simultaneously time resolved with system S.N.R. of 3 at 60 picosecond time resolution without post intensification. Absolute photometric evaluation is given in the dynamic mode, i.e. while operating in the picosecond time domain. Such quantitative data has been lacking in the past, particularly for multiple channel applications.
Reciprocity Failure Of Phosphors Used In Streak Cameras
Shorn Majumdar, Samprasad Majumdar
A reduction in the efficiency of phosphors ( P 11 & P 20 ), when used in picosecond streak tubes is reported. A loss of the order of 100 times is estimated. This is identified as the main reasonfor the inability of present day streak cameras to record single photo-electrons from the photo-cathode of the streak tube. It is suggested that work should be carried out on the efficiency of phosphors energised by sub-nanosecond bursts of electrons. The authors suspect that the use of a silicon target instead of a phosphor will vastly improve the recording ability of a streak tube as the efficiency of such a transducer is not expected to fall drastically for short duration electron pulses.
Video Scene Recognition System
Robert Y. Wong, Rashid M. Sallak
Microprocessors are used to show a possible implementation of a multiprocessoi system for video scene recognition operations. The system was designed in the multiple input stream and multiple data stream (MIMD) configuration. "Autonomous cooperation" among the working processors is supervised by a global operating system, the heart of which is the scheduler. The design of the scheduler and the overall operations of the system are discussed.
Application Of High Speed Videography For Study Of Complex Three-Dimensional Water Flows
Charles R. Smith
The application of an INSTAR high-speed video system for the study of complex water flows via flow visualization techniques is described. Three examples are presented which illustrate how the various characteristics of the videographic system, particularly the split-screen capability, have been utilized to view and examine the behavior of time-varying, three-dimensional flows. Several particularly significant adaptations of the system are discussed, including 1) the use of a fiber optic lens for on-line, underwater viewing of flow behavior and 2) interfacing of split-screen video pictures with a computer-aided display to recreate three-dimensional flow patterns.
Advanced Technics In Applications Of High Speed Videography
Toshiyuki Yamamoto
The demand for clarifying high speed phenomena exists widely. Conventionally, researchers and engineers have relied on high-speed cinematography (HSC) but the recent trend is foward greater use of high-speed videography (HSV) in many fields. HSV, when compared to HSC, admittedly, has some drawbacks, but it has advantages that more than outweigh such drawbacks. Because of these advantages, wider acceptance of HSV is expected. In this paper, recent cases of applications of HSV are introduced.
Computer Control Of A High Speed Video Recording System
Todd Cooper, Joe Saunders
Two common computer interfaces have been developed for a high-speed video recording system which greatly increases its versatility in data acquisition and analysis. The serial RS-232-C .nd. parallel IEEE-488 interfaces have been implemented on a large number of computer systems, from desktop/portable micros to large main frames, and have been used extensively in laboratory environments. Using these interfaces with the SP2000 Motion Analysis System, the operator is able to remotely control the system and access all the video and ancillary data. Thus, in addition tothe video system's ability to provide instant replay of a recording, a host computer can provide instant data analysis, two features which can make a significant impact on a project's time and cost. Some of the data processing capabilities made possible are pattern recognition, image enhancement, and standard coordinate based analyses (e.g. X/Time, Velocity/Time, Displacement/Time).
Video Application With High Speed Mechanical Assembly Equipment
Barney E. Wallace
State of the art technology computer graphics and video photography have enriched the process in which mechanical assembly and material handling systems can be monitored. This technology, used correctly, can generate real time system analysis. The computer graphic system of information gathering is totally flexible in that it can be reprogrammed off-line and then placed into actual production after the new program is completed. The video photography system is exceptional in the de-bug process and system monitoring and allows one (1) hour of production run history to be recorded.
High Speed Data Acquisition Of Tracked Targets From Film And Tv Video Sources Using The Semi-Automatic Video Recording System (SAVRS)
Earl K. Jones
The DBA's SAVRS System provides a complete stand-alone measurement system for measuring, processing, and recording video data from 35 mm film and video cassettes. The system will automatically, encode and process frame border data such as, azimuth, elevation, and time, in addition to, automatically tracking high-contrast video targets. On lower-contrast targets or targets requiring redefined measurements, the operator can manually measure, via a trackball and cursor, and record the measurements through a footswitch entry. The SAVRS System operates in one of three distinct modes: 1) manual, 2) semi-automatic, and 3) automatic. The mode is determined by the type data to be processed and the quality of the video input to the system. In addition to the main console in the SAVRS System, an optional previewing station is available for determining which sections of the input media contain valid target information for measuring. During the recording process, while azimuth, elevation, and time data are being captured, a computer-generated target may be superimposed on the actual target. By using the optional attitude control system, the roll, pitch, and yaw of the moving target can be determined at any given time.
High Speed Television Photon-Counting System For Recording Low Intensity Spectra
Yu. G. Vainer, L. P. Malyavkin, E. G. Silkis, et al.
High-speed television photon-counting system with digital accumulation was developed for Raman laser spectroscopy.Photosensitive detector consists of three stage image intensifier optically coupled to television tube isocon. The electrostatic gate system of the image intensifier allows to record spectra at the nanosecond time range. The system was used in Raman lidar for remote control of air pollution and in laboratory laser snectrometer for studying Raman spectra molecules SF6 and CF31 excited by CO2 laser. Spectra of various gases recorded by TV system are represented.
High Repetition Rate, High Resolution Shutterless Photography For Gas Dynamic Studies
Lee A. Cross, Edward A. Strader
A system for the production of high resolution, high repetition rate cinephotographic records has been developed at the University of Dayton Research Institute. Such a system consists of a short-pulse duration, high repetition rate metal vapor laser illuminator and an extremely simple film transport. By using a short-pulse duration laser illuminator capable of operating at high PRF it is possible to produce long, detailed, and high resolution photographic records of a variety of types. Such a photographic system can be applied to the analysis of a very wide variety of difficult subjects. Front-lit, speckle, back-lit, shadow, and schlieren photographs have been recorded at framing rates above 10 kHz using 16 mm reel-to-reel and 35 mm rotating drum cameras. The short (20 ns) pulse duration of the laser illuminator effectively stops the motion of both the object and the camera film so that no motion compensating optics are required. Specific examples of the applicability of the shutterless photography to difficult subjects such as burning rocket fuel, mechanical systems undergoing rapid deformation, and rapidly evolving gas dynamics systems such as dump combustors and ramjets are described.
High Speed Photography Of The Interaction Of Shocks With Voids In Condensed Media
M.Munawar Chaudhri, Lars-Ake Almgren, Algot Persson
High-speed photography has been made of the collapse of 2.5-10 mm diameter glass and aluminium hollow spheres by water shocks of strength 5-20 kbar. The camera used was a multiple Kerr-Cell type, framing at speeds of up to 2 million frames second. The collapse process has been shown to be asymmetrical giving rise to 'jetting'. The impact of the 'jet' on the front wall of the void results in a localised secondary shock of intensity approximately equal to that of the primary shock. It is proposed that it is the localised secondary shock which is responsible for the sensitization of explosives containing gas pockets/voids.
High Speed Diagnostics Of Laser Generated Shock Waves In Liquids
David C. Emmony, Jan-Willem Gemmink
A brief review of the laser-liquid interaction is presented. A 1 nanosecond duration nitrogen laser has been used as the light source for Mach Zehnder interferometry of the first few microseconds following the impact of a carbon dioxide laser pulse on water and partially transmitting cyclohexane. Quantitative analysis of the interferograms using an Abel inversion procedure has been carried out. Ultra violet laser induced cavitation has been observed.
High Speed Interierometric Study Of Unstationary Shock Wave Processes
W. Heilig, H. Reichenbach
The gasdynamic process of shock wave reflection at a curved obstacle performed by shock. tube runs is visualized interferometrically with the aid of a Mach-Zehnder interferometer. A. fast rotating prism framing camera in connection with a special point light source of adjustable duration produces about eighty colored interferograms with finite fringe width, the time-distance being constant (1 or 2 microseconds). Evaluation. of interferograms yields shock front pressures which are compared with pressure values gained by piezo-electric measurements.
Application Of Stroboscopic Laser Schlieren Photographic Technique To Explosion Events
Pai Lien Lu, Ralph Landini, Asuncion Lacson
A stroboscopic laser schlieren system was constructed by using commercially available instruments. Its application to explosion studies was demonstrated by recording an exploding EBW detonator. Owing to the superior resolution of this system, 150 micron fragments traveling at a speed of 2.7 mm/psec can be resolved.
Slit-Drum Camera For Projectile Studies
Chen Liangyi, Zhou Shaoxiang, Cha Guanhua, et al.
The' model XF-70 slit-drum camera has been developed to record projectile in flight for observation and acquisition. It has two operation modes: (1) synchro-ballistic photography, (2) streak record. The film is located on the inner surface of rotating drum to make it travel. The folding mirror is arranged to reflect light beam 90 degree on to film. The assembly of folding mirror and slit aperture can be together rotated about the optical axis of objective so that the camera makes a feature of recording projectile having any launching angle either in synchro-ballistic photography or in streak record through prerotating the folding mirror assembly by an appropriate angle. The mechanical-electric shutter preventing film from reexposing is close to the slit aperture. The loading mechanism is designed for use in daylight. LED fiducial mark and timing mark are printed at the edges of the frame for accurate measurements.
Image Shutters: Gated Proximity-Focused Microchannel-Plate (MCP) Wafer Tubes Versus Gated Silicon Intensified Target (SIT) Vidicons
G. J. Yates, N. S. P. King, S. A. Jaramillo, et al.
The imaging characteristics of two fast image shutters used for recording the spatial and temporal evolution of transient optical events in the nanosecond range have been studied. Emphasis is on the comparative performances of each shutter type under similar conditions. Response data, including gating speed, gain, dynamic range, shuttering efficiency, and resolution for 18 and 25-mm-diam proximity-focused microchannel-plate (MCP) intensifiers are com-pared with similar data for a prototype electrostatically-focused 25-mm-diam gated silicon-intensified-target (SIT) vidicon currently under development for Los Alamos National Laboratory. Several key parameters critical to optical gating speed have been varied in both tube types in order to determine the optimum performance attainable from each design. These include conductive substrate material and thickness used to reduce photocathode resistivity, spacing between gating electrodes to minimize interelectrode capacitance, the use of con-ductive grids on the photocathode substrate to permit rapid propagation of the electrical gate pulse to all areas of the photocathode, and different package geometries to provide a more effective interface with external biasing and gating circuitry. For comparable spatial resolution, most 18-mm-diam MCPs require gate times > 2.5 ns while the fastest SIT has demonstrated sub-nanosecond optical gates as short as r, 400 ± 50 ps for full shuttering of the 25-mm-diam input window.
Overview Of Pulsers For Nanosecond Gating Of Image Shutter Tubes
G. J. Yates, J. W. Ogle, N. S.P. King, et al.
The capability of generating a useful optical shutter of a few nanoseconds or less utilizing gated proximity-focussed microchannel-plate (MCP) wafer tubes or silicon intensified target (SIT) vidicon tubes depends strongly on the driving electrical pulse. A proximity-focussed MCP wafer tube can be optically shuttered by applying a short electrical pulse between the photocathode and MCP interface.' This interface is electrically reverse-biased by approximately 30V to prevent photocathode electrons from reaching the MCP. The gating pulse, typically 80V, is of opposite polarity to generate an effective forward bias to "shutter" the system. Light intensity ratios for gated on to off conditions (shutter ratios) of greater than 105 are obtained. The more recently developed gated SIT vidicon tubes2 are gated by applying an effective forward bias between the photocathode and a 50% transmission grid in close proximity to the photocathode. Equivalent shutter ratios have not been achieved as yet, with 103 shuttering efficiency measured for typical SITs. Assuming the optical gate width is determined by the electrical gate width one requires pulses with rise and fall times of less than a nanosecond and amplitudes in excess of 80 volts into a 50 ohm impedance. Such pulses have permitted shutter times of %1.5 ns and L800 ps for the MCP and SIT tube systems respectively while preserving their resolution capabilities. The problem of matching an electrical pulser's driving impedance to that of the optical shutter is one still under study. The intrinsit impedance of a proximity-focussed MCP optical shutter is that of a distributed capacitance and resistance.1r3 A measurement of the resistance and capacitance vs a frequency network of 10 MHz with an HP4191A impedance analyser indicated a relatively constant equivalent series capacitance of 31 pf and a photocathode equivalent series resistance in the range from <100 to 300 for individual intensifiers. The capacitance values are roughly independent of frequency up to ',1,120 MHz. For frequencies >120 MHz, and therefore gate rise times less than %3 ns, the equivalent series inductance becomes effective causing varying impedance values which complicates the problems of electrically driving these systems. This paper will provide a summary of some of the electrical gate pulsers utilized in studying both proximity-focussed MCP imaging intensifiers and gated SIT FPS vidicon tubes. All of these pulsers are designed to drive 500 impedances although work is currently being directed to lower impedances. The circuit diagram for a 1.6 ns FWHM, 80V pulser based on avalanche transistors is given in Fig. 1. An overview of the MCP image intensifier and its associated divider string is also shown. The output pulse with the system terminated in 500 without the MCP intensifier attached is given in Fig. 2a. This pulser is capable of driving a MCP intensifier from '1,1.2 ns to 5 ns total optical shutter on times. The optical resolution is reduced to below 443/mm for shuttering intervals <2 ns for total on/off times. The variable optical shutter times are obtained by varying the reverse bias applied between the photocathode and MCP. There is a limit as to how low a reverse bias one can use. This is determined by the "ringing" caused by improper impedance matching of the pulser to the optical shutter. This mismatch can be seen in Fig. 2b, obtained by observing a 1% sample signal at the input to the optical shutter. The second pulse will turn on the optical shutter thereby extending the shutter duration. Two alternative methods of driving proximity-focussed MCP image intensifiers involving the above pulser are to form a bipolar pulse (shown in Fig. 3) through feedback summation and to attempt improved impedance matching by coupling through a toroid (pulse transformer) and a constant impedance network. The toroid system is schematically shown in Fig. 4. Both methods reduce the total available amplitude by 50%, resulting in insufficient
Portable Ultrahigh Speed Photographic Field Laboratory Suitable For The Study Of Self-Luminous And Nonluminous Detonations In Solid High Explosive Charges (10 To 130 Pound TNT Equivalent)
A. W. Gibb, M. A. Nolan, J. B. Dempsey
Studies of detonation phenomena in solid high explosive charges at Defence Research Establishment Suffield, undertaken in 1977, generated a requirement for a photographic range facility which would permit ultra-high speed photographs of large explosive charges to be taken at close range, and which would also be light enough in weight to be portable. This paper describes the successful design and operation of a photographic field facility which satisfies both of these competing criteria.
Application Of An Exploding Wire Capping Shutter To The Study Of Solid High Explosive Charges Using An Ultrahigh-Speed Rotating Mirror Camera
A. W. Gibb, R. Naylor, M. A. Nolan, et al.
The Explosives and Engineering Group at Defence Research Establishment Suffield (DRES) has developed a portable field laboratory containing an ultra-high speed camera (Cordin Model 330A) for the study of detonation processes in solid high explosives. The camera is of the rotating-mirror type, the image being swept repeatedly over stationary film as the mirror rotates. The writing period is continuously adjustable from 40 microseconds to 400 microseconds, but the mechanical shutter closes on a time scale of milliseconds. In order to prevent optical over-write (multiple exposure) of the film due to the highly-luminous cloud of detonation products from the detonating explosive, an auxiliary, rapid-closing shutter must be utilized. This paper describes the successful design and use of an electronically-operated exploding-wire capping shutter which has an activation time predictable to within ±1 microsecond. The shutter principle is the same as that described by Edgerton and Strabalal. The unit developed at DRES has the ability to attenuate light by a factor of three hundred in fifteen microseconds, over a circular viewing area 10.2 cm (4 inches) in diameter.
Role Of High Speed Photography In The Testing Capabilities Of The Arnold Engineering Development Center (AEDC) Range And Track Facilities
Roy E. Hendrix, Paul H. Dugger
Since the onset of user testing in the AEDC aeroballistic ranges in 1961, concentrated efforts in such areas as model launching techniques, test environment simulation, and specialized instrumentation have been made to enhance the usefulness of these test facilities. A wide selection of specialized instrumentation has been developed over the years to provide, among other features, panoramic photographic coverage of test models during flight. Pulsed ruby lasers, xenon flash lamps, visible-light spark sources, and flash X-ray systems are employed as short-duration radiation sources in various front-light and back-light photographic systems. Visible-light and near infrared image intensifier diodes are used to achieve high-speed shuttering in photographic pyrometry systems that measure surface temperatures of test models in flight. Turbine-driven framing cameras are used to provide multiframe photography of such high-speed phenomena as impact debris formation and model encounter with erosive fields. As a result, the capabilities of these ballistic range test units have increased significantly in regard to the types of tests that can be accommodated and to the quality and quantity of data that can be provided. Presently, five major range and companion track facilities are active in conducting hypervelocity testing in AEDC's von K6rman Gas Dynamics Facility (VKF): Ranges G, K, and S-1 and Tracks G and K. The following types of tests are conducted in these test units: ablation/erosion, transpiration-cooled nosetip (TCNT), nosetip transition, heat transfer, aerodynamic, cannon projectile, rocket contrail, reentry physics, and hypervelocity impact. The parallel achievements in high-speed photography and testing capabilities are discussed, and the significant role of photographic systems in the development of the overall testing capabilities of the AEDC range and track facilities is illustrated in numerous examples of photographic results.
Possibility Of Simultaneously Attaining The Curve Without Out Of Focus And With Constant Writing Speed
Li Jingzhen
Eugene A. Igel says that the axis of a rotating mirror of finite thickness is not located at the reflective surface, a condition not easily obtained, a noncircular cylindrical focal surface is generated. This nonideal condition allows either a perfect focous or a constant writing speed, but not both simultaneously. So do A. C. _ H. Edels and D. Whittacher, 3 resectively. Nevertheless, from the recent study it can be found out and theoretically demonstrated that the curve with constant writing speed and without out of focus can simultaneously be brought into being, and applied to some of high speed recording systems with cathoderay tube or that with leser leam.
Optimizing In High Speed Photography
Li Jingzhen, Zhang Yaoming
This paper describes some of optimizitions in high speed photography, such as optimizing the aperture width for each image speed of a studed object in a rotating mirror framing camera, optimizing the rotating mirror speed for each slit width in a smear camera, optimizing designs of a rotating mirror camera and intermittentmechanism in a intermittent camera through the differentiation and calculation by means of computer, and selecting the optimiz-ed photographic frequence in the application of high speed camera. Finally, we deduce it is possible that smear cameras can be partially replaced with the framing camera through the data processing in some cases.
Generation Of A Shock Pressure By Exploding A Wire In Water
Toshiro Yamada, Kouki Kani
A fine wire was exploded in water by rapid release of energy stored in a condenser bank to generate a shock pressure in water. In order to clarify the mechanism of shock-pressure generation, the exploding process of the wire and the motion of a cavity produced by the wire-explosion were observed by a high speed streak camera and a framing camera respectively. Electrical quantities of the discharge and the shock pressure were also measured simultaneously with the optical observation. It was found that shock pressure was emitted from the wire when the wire was vaporized. The cavity formed in water by the wire-explosion collapsed spherically after maximum expansion and reversely expanded after reaching minimum radius. Shock pressure was generated at the start of this expansion.
Photographic Study Of A Dead-Pressed Explosive
G. M. Swallowe, J. E. Field
High speed photography in conjunction with electron microscopy and a pressure measuring technique have been used to investigate the differences between dead-pressed and non-dead-pressed samples of the primary explosive Mercury Fulminate (Hg Ful). Photographs of reaction propagation were taken in transmitted light using a specially adapted drop-weight machine with transparent anvils. The results of these experiments suggested a mechanism for dead-pressing in Hg Ful based on the microscopic internal structure of the compacted explosive.
New High Resolution, Large Format Eight-Frame Image Converter Camera With Ten Nanosecond Exposure Time
D. L. Paisley, J. H. Owren
A new electronic image converter camera has been developed that has high resolution (>20 1p/mm), large format (75 mm diameter) for each frame, and the capability of short (10 nanosecond) exposure times. The camera is designed so that each of eight frames can be pulsed on individually thus permitting variable interframe times within a given event from < 10 nanoseconds to 1 millisecond. Eight separate 75 mm diameter proximity focussed image diodes are aligned on a common optical system using only one objective lens and beamsplitting the optical information to each diode. This technique eliminates any image parallax between frames, but also reduces the amount of light reaching each image diode. This reduced light level at each diode is more than compensated for by the optical gain of the diodes and the fact that each diode is fiber optically coupled to the recording film. The design of the camera permits the optical system for each diode to be independent. This capability allows for an unlimited number of optical arrangements such as: four (4) stereopairs of images, four (4) orthogonal image pairs, or even recording images of eight (8) separate events that must be optically correlated. In general, this type of camera has proven to be extremely versatile in optically recording ultra-high speed events.
High Speed Cinematographic Investigations Of The Interaction Of Pulsed Laser Radiation With Liquids
Manfred Hugenschmidt, Joseph Wey, Werner Baca
With regard to scientific research and technical applications considerable work has been done for many years in studying the interaction of high power laser radiation with matter in the gaseous, liquid or condensed phase. The present paper is concerned with recent investigations of the impact of powerful CO2 laser pulses on liquid targets. Pulse energies are in the range of several tens of J at power densities up to several 108W/cm2. The absorption of the laser radiation in a thin surface layer leads to rapid heating and vaporization and above certain threshold intensities to the formation of strongly ionized plasmas. In this case high pressures are building up causing even large amounts of liquid material to be ejected. The pressures were determined quantitatively by means of quartz gages. In order to determine the influence of frictional forces two liquids that is water and polyethylene glycol, were investigated at energy densities ranging from about 3 to 15 J/cm4. High-speed cinematographic techniques were used for visualizing these transient phenomena and for obtaining quantitative information on the velocities of the plasma expansion, the vapor clouds, the shockwaves propagating inside the liquids and the ejection of liquid jets or droplets. A rotating-mirror streak camera and a multiple spark camera was operated at the same time. Their recordings could thus be correlated to the laser parameters (energy and power) and to the laser induced pressures that were obtained simultaneously in each shot.
High Speed Photography Of The Rear Side Bursting Process During Plate Perforation
A. J. Stilp, V. Hohler, E. Schneider
Perforation, especially the break-through of a projectile at the rear surface of a rolled steel plate is a highly complex event. Shock wave effects and a large amount of deformation cause failure of the target material at the exit surface of a barrier. The perforation failure processes are strongly influenced by target material (ductile, brittle), projectile shape, and perforation velocity. Two different modes of peripheral fragments are formed in the rolled steel plate by the perforating projectile: fracture parallel and perpendicular to the rolling texture of the steel plate. The formation process of this fracturing, beginning with buckling of the exit surface in the vicinity of the break-through point of the projectile, and ending with the break-out of the residual projectile is observed by means of flash X-ray techniques. Steel and high density metal rods are used as projectiles. A smooth bore powder gun allows the acceleration of these projectiles up to impact velocities of 1800 m/s. Three, respectively four X-ray sources are aligned at the rear surface of the target for cineradiography of the buckling and fracturing processes.
High-Resolution Velocity Interferometer System For Any Reflector (VISAR) Laser Interferometer Measurements Of The Rear Side Response Of Impact Loaded Steel Plates
G. F. Kuscher, V. Hohler, A. J. Stilp
Results of investigations of the rear side movement of RHA-plates under impact conditions are reported. Special emphasis is given to the rear side bursting processes, in an effort to get more detailed information about the time sequence of these processes and their mechanisms. By impact of thin disks and long rods, planar and hemispherical shock waves have been produced within the target plates. The rear side movement of the impact loaded plates was measured by means of a VISAR (Vqlocity Interferometer System for Any Reflector)-laser-interferometer. Thus, a quasi-continuous velocity-time-history of the whole process was obtained with a maximum time resolution of 5 nsec. The time sequence and the measured shock wave amplitudes of the rear side movement of the plate for the above mentioned loading conditions are completely different. This yields two different rear side fracturing mechanisms which will be discussed.
Application Of Schlieren Method On The Flow/Combustion Problems In High Speed Diesel Engine
M. Hrus, Z. Melich
In the present study high - speed kinematography was used to visualise and investiga4 to events in combustion chamber of direct injection Diesel engine. Schlieren apparatus was developed for the application on the engine. The system enables the visualisation of the working cycle by keeping the inlet and exhaust ports intact, which is a relevant factor in the study of aerodynamical efficiency.
ZDF-50 Type Waiting Framing Camera
Xu Jialong, Lang Jianlin, Sun Fengshan, et al.
The description of the general outline and the main performances of the ZDF-50 type waiting framing camera is given in this paper. The waiting operation of the camera ;,s based on the triangular mirror which is drived by a motor. The framing rate is 5x10) pictures/sec at a rotor speed of 1500 rps. A circuit can record 110 frames with a frame size of 10x18 mm. The relative aperture at the film is about f/19. The dynamic photographic resolution is from 22 to 25 1p/mm. The framing lens consists of a doublet and a meniscus element. There are two objectives, each of them is suitable for using in the field and in the laboratory respectively, and three forms of shutters: electromagnetic shutter, fast open shutter and blast shutter. The rotating mirror house of the camera is vacuumized. A transistor circuit and digital display are incorporated into the control system of the camera. The operation of the instrument is accomplished automatically. Lastly, the detonator exploding pictures taken by this camera are presented.
Optically Recording Velocity Interferometer System (ORVIS) For Subnanosecond Particle Velocity Measurements In Shock Waves
D. D. Bloomquist, S. A. Sheffield
An optically recording velocity interferometer system (ORVIS) has been developed to measure particle velocity with subnanosecond resolution for shock waves in condensed matter. The fringe pattern of a wide-angle Michelson interferometer was focused as a set of dots on the slit of a high speed streak camera, resulting in a continuous record of the fringe position as a function of time. This technique was employed to measure the particle velocity of a witness foil in a series of experiments to study the nature of detonation-driven shock waves. The present experiments demonstrated a time resolution of about 300 ps, and we believe that 20 ps resolution may be achievable with this technique. The improvement in time resolution of up to two orders of magnitude over current diagnostic techniques will be an aid in the study of several aspects of shock wave phenomena such as shock front thickness, detonation wave theory, fast relaxation at an impact plane, and fine structure in shock fronts associated with chemical reaction.
Multiple Shock-Waves Collisions And Energy Balance In Ionized Gases
Serge Prohoroff
A H-tube shock facility has been designed and realized. Symmetry and synchronism have been confirmed by observational techniques. Filling gas pressure and capacitors voltage are the most sensitive parameters. Different confogurations of attached and detached shocks were recorded. In the later regime, both plasmas are repelled by reflected shocks and the plasmas preceed the shock-waves. Under certain circumstances, even a slightly ionized plasma is generated at the very spot of the shocks collision. When the shock-waves merge into the plasma fronts, the plasma starting fram the collision region is persistant and fills the volume left behind the reflected shocks. The radiation intensity and its time duration depend strongly on the gas and the energy stored in the capacitors.
Optical Pulse Generators Using Semiconductor Lasers With Electron Pumping
Yu. A. Akimov, A. A. Burov, A. I. Kordumov, et al.
Soon after the construction of injection semiconductor lasers the method of pumping the semiconductor lasers by a beam of accelerated electrons suggested by the Soviet scientists (N.G. Basov and his colleagues) was put into practice.
Crantz-Schardin Method In The Parallel Beams
V. S. Sukhorukikh, A. I. Kharitonov, J. L. Sharov
An instrument of Crantz-Schardin on the base of mirror-lens schlieren device of the collimator type with the aperture of 230 mm and the focal length of about 2000 mm has been created. The use of this instrument makes it possible to registrate four black-and-white or colour schlieren patterns. Impulse xenon capillary lamps and ruby lasers are used as light sources. Conventional or cross-model slits used for the registration of black-and-white and colour schlieren patterns are fixed in the focal plane of the collimator. The illumination of cross-model slit by the linear light source is achieved by means of the special optical device with the two-mirror reflector. Black-and-white schlieren method has been realized by means of the conventional Foucault knife and colour schlieren method by means of four cross-situated knives. It is possible to registrate the patterns with the diameter of 25 mm or 40 mm.
Perspectives Of High Speed Cameras Design With High Image Quality
A. V. Belinskiy, A. S. Dubovik
Image quality of the high-speed rotating mirror framing camera is mainly determined by mirror scanning assembly errors (since a rotating mirror surface is away from its center of rotation l) and optical system aberrations. This paper describes image quality improvement possibilities associated with the mirror scanning assembly. A new analytical design method of camera parameters calculation is also presented. The resulted parameters ensure the highest possible image quality.
High Speed Interferometric Method For Density Field Investigation In A Boundary Layer Behind The Shock Wave
Alexander A. Kon'kov, Evgeny A. Kozjukov, Vladimir I. Bumblis
The spectrointerferometric method of density profile retrieval in a boundary layer behind the shock wave is discussed in the utility of Mach-Zehnder interferometer crossed with spectrometer. The high-speed rotating mirror camera provides spectral interferogramms in range from 100,000 to 4,000,000 frames/second. Interferogramm processing and evaluation of density profiles in a boundary layer were obtained using an interactive image analysis system, integrated with specially oriented microprocessor configurations.
Electron-Optical Photochronograph FER-11
R. G. BeI'govskaya, G. V. Kolesov, V. B. Lebedev, et al.
The paper describes the specific schematic and structural features of a photochronographic camera FER-11 which is characterized by a controlled light amplification coefficient and used for the analysis of electric discharges occuring at long intervals, and also of lightning.
Registration Of Shock Waves Generated By Plasma In Delphin-1 Set
N. G. Basov, A. I. Valuyev, B. L. Vasin, et al.
The device for high-speed photography of rapidly changing transparent objects is described. The 19 frame picture of the laser formed strong shock wave made by this device is presented. The data of measurement of shock wave parameters are given, when ionization and radiative processes are taken into account. Among optical methods of laser plasma study of great significance is high speed frame photography by the method of laser illumination of the target. The method makes it possible to assess the fractional energy absorbed by plasma, the ion temperature, the degree of uniformity of the target irradiation, as well as other parameters1-5. The accuracy of measurements follow from the object parameters. This paper deals with the description of the device for shock wave ph9t9graphy forming during expansion of a spherical target heated 147 six beams in "Delphin-1"-°. The frame rate varies from 200 millions to 300 thousands sec-I at exposure equal 1.2 ns and at total number of frames - 19. This device provides the accuracy of registration of amplitude and phase optical of the target and plasma equaled to 30 lines/mm. The optical scheme of 19-frame device for shadow photography (DSP) is presented in Figure 1. It consists of the ruby laser 1, coordinating device 2, optical delay line 3, light splitting plates 4, telescopic expanders 5, matrix mirrors 6,7, converging mirror 8 and photocamera 9.
Continuous Duty Lighting Calculations And Techniques For High Speed Photography
Thomas L. Pincu
An understanding of basic lighting technology, calculations, and applications is necessary to arrive at appropriate intensity levels and coverages in high speed photography. These factors coupled with an understanding of film emulsions and the effects of lens apertures on exposure and lighting requirements result in effective lighting levels for high speed photographic data acquisition as well as cost effectiveness in budgetary controls. Techniques for reduction of infra-red energy on heat sensitive subjects are discussed as well as exposure increases mandated by the use of tubes or extension bellows. High intensity D.C. "Flicker-less" light sources and their application are discussed. These sources are capable of generating incident lighting intensities in excess of 20,000 foot candles at 50'.
Lighting Systems For High Speed Photography Applying Special Metal Halide Discharge Lamps
Keith M. Gillum, K. H. Steuernagel
High speed photography requires, in addition to a good color quality of the light source, a very high level of illumination. Conventional lighting systems utilizing incandescent lamps or other metal halide lamp types has inherent problems of inefficient light output or poor color quality. Heat generated by incandescent lamps and the power these sources require drive up operating and installation costs. A most economical and practical solution was devised by using the metal halide discharge lamp developed by OSRAM, GmbH of Munich, West Germany. This lamp trade marked the HMITM Metallogen® was primarily developed for the needs of the television and motion picture film industry. Due to their high efficiency and other consistent operating qualities these lamps also fulfill the needs of high speed photography, e.g. in crash test facilities, when special engineering activities are carried out. The OSRAM HMITM lamp is an AC discharge metal halide lamp with rare earth additives to increase both the efficiency and light output qualities. Since the lamp is an AC source, a special method had to be developed to overcome the strobing effect, which is normal for AC lamps given their modulated light output, when used with high speed cameras, (e.g. with >1000 fps). This method is based on an increased frequency for the lamp supply voltage coupled with a mix of the light output achieved using a multiphase mains power supply. First developed in 1977, this system using the OSRAM HMITM lamps was installed in a crash test facility of a major automotive manufacturer in West Germany. The design resulted in the best lighting and performance ever experienced. Since that time several other motor companies have made use of this breakthrough. Industrial and scientific users are now considering additional applications use of this advanced high speed lighting system.
Laser Stroboscopic Interferograph With Optical Vibrator
Xia Sheng-jie
An optical vibrator was mounted in a He-ne laser interferometer as a modulator, in co-operation with a rotating drum camera to form a high-speed stroboscopic interferograph. Some series of interferograms with rates within 20,000 pictures per second have been obtained.
Study Of Wavefronts In Acoustic Diffraction Patterns Using A Stroboscopic Schlieren Technique
D. R. Andrews
Ultrasonic waves in water (wavelength 2.00 ±0.01 mm) were generated in packets of approximately 15 wavefronts at repetition rates in the range 200 - 2000 Hz. They were rendered visible using a 'Z' configuration schlieren system and a stroboscopic light source driven at the same repetition frequency. The light source was a GaAsP light-emitting diode cooled to a temperature of approximately 80 K producing light flashes of variable duration (50 -200 ns). Various obstacles were placed in the path of the waves: cylinders, an acoustic diffraction grating, and a reflecting surface of variable geometry. The behaviour of the wavefronts in the vicinity of the obstacles and in their diffraction patterns were examined. Certain diffraction amplitude zeros are shown to be lines of anomalous phase or wavefront dislocations. Dislocations have also been located in the caustic cusp focus from reflecting surfaces; a result which is in good agreement with catastrophe theory.
Determining Light Intensity For Use With Intermittent Or Rotating Prism Cameras Utilizing A Cinematographic Light Intensity Translator
Arthur A. Rodriguez
A problem at test ranges is the acquisition of valid light intensity measurements at remote camera tracking or fixed camera sites. After all instrumentation is set up and ready to go, one of the last things to be done is to determine what f/stops and shutter settings should be used. Known factors always exist, such as type of camera (intermittent or rotating prism), and type of film in use. Assuming the operator has no automatic exposure control, he now has to measure the ambient light. Keep in mind that not all personnel who track or set up cameras are professional photographers. The operator may use his light meter to take a reading, or it may have been forgotten, misplaced, or dropped, out of calibration, or have weak or no batteries. Or worse, he may use the light meter incorrectly. Use of the Cinematographic Light Intensity Translator eliminates the inconsistencies of range light measurements. The Range Camera Controller (coordinator) has the light measurement console at one central location with a primary sensor and remote sensors located as needed. By rotating a thumbwheel, the controller can select the output of a specific sensor at any given time. By looking at the CRT display, he can give any range camera operator the specific setting. Prior to the test, the controller enters all known camera factors for up to 50 functional stations into the minicomputer using the alphanumeric switch matrix on the control unit. The remote sensors, usually placed near the impact target or near ground zero, continuously generate and transmit the EV. All settings are given to the camera operators via rf radio net. At Tonopah Test Range (TTR), I have sent out changes within 90 seconds of drop or firing time without interrupting the test. The CRT also displays whether the film from each camera location needs to be under, or force processed.
Visualization Of Stress Waves In Flawed Solids With A Multilaser Camera
R. J. Sanford, R. G. Hughes
Because stress-waves interacting with a flaw are not only diffracted and reflected but also converted from one type of wave into another (mode converted), it is very difficult in many cases to identify the source or propagation direction of a particular wave with an ultrasonic transducer. Visualization of the stress-wave flaw interaction provides a technique whereby the time history of the interaction can be observed and the resulting wave shapes, direction of propagation and nature of mode conversion identified. The visualization method used in our study is photoelastic visualization. Although earlier studies have used a similar visualization technique, the camera systems used lacked sufficient dynamic resolution in the image plane to enable identification of the waveform and spatial stress distribution after the interaction of the incident stress-wave with a flaw. In this study we show stress distributions in propagating stress waves and mode converted waves in transparent solids using a high-speed, multi-laser camera system. The camera system light sources consist of six ruby lasers in contrast to spark-gap sources used in earlier studies. The lasers are operated in the Q-switched mode and provide an exposure time of 35 nanoseconds for each frame. The framing rate is controlled wit4 either a microprocessor or a set of passive digital delays over the range of 0 to 10' frames/sec. Light output from the lasers is directed to the camera system via optical fiber bundles. A Cranz-Schardin lens configuration is used to record images on a stationary film plane.
High Speed Absorption Line Profile Measurements Using A Rapidly Tunable Dye Laser
D. Meiners, G.-J. Deppe, H. Rybach
Absorption line profiles of instationary plasmas have been measured in a few hundred nanoseconds using a special flashlamp-pumped dye laser as a light source. This laser can be tuned during a single pulse over more than 1.5 nm with a tuning velocity of 3.4 nm/us. This is achieved by inserting a four-element electrooptical birefringent filter (Lyot-filter) into the cavity. The laser shows self-mode-locking with consecutive pulses having a wavelength separation of 0.03 nm. Absorption profiles of the Krypton I line 587.1 nm could be measured in 200 ns. The line was Stark broadened in a shock wave plasma.
Picosecond Streak Tube Line Spread Function (LSF) Investigation By Using Ultrashort Light Pulses
V. P. Degtyareva, M. V. Gorbunkov, A. M. Prokhorov, et al.
Line spread function (LSF) of a picosecond streak tube mainly depends on photoelectrons initial velocity distribution and on the time dispersion of electrons. An experimental tech-nique for direct LSF definition based on application of subpicosecond light pulses from Rho-damine-6G dye laser is developed. The obtained experimental results make it possible to construct a more reliable model for streak image tube behaviour in subpicosecond temporal range.
Optical Tomography At A Limited Number Of Projections
G. N. Vishnyakov, G. G. Levin, B. M. Stepanov, et al.
The analysis of transient processes (TP) is facing information processing systems with more and more complex tasks. At present it is the measurement of the spatial distribution of the objects' internal heterogeneity and their temporal variation which is focusing the attention of researchers. The tomographic method (1) makes it possible to obtain the distributions of the absorption coefficient or the refractive index over the cross-section of a three-dimensional object. Tomography is a two-stage process. In the first stage the object under study is probed by penetrating radiation at different camera angles (aspects), and the field of the transmitted wave (the so-called projection) is recorded.
Application Of Pulsed Laser Holography To Nondestructive Testing Of Aircraft Structures
Hubert Fagot, Paul Smigielski, Jean-Louis Arnaud
Subsequently to laboratory tests, experiments were conducted on an aircraft undergoing maintenance in order to assess the possible uses of holographic interferometry for non-destructive testing of large aircraft structures. A double ruby laser was used delivering two pulses with a duration of 20 ns each. The two pulses are separated by an arbitrary time interval At which is determined as a function of both the amplitude and frequency of the surface displacement. Shocks of the order of 100 mJ cause the structure under investigation to vibrate, the time interval At thereby ranging from 10 to 100 ps for a delay of a few ms after shock initiation. The method used is relatively insensitive to environmental disturbances. Although the laser delivers pulses of light of less than 100 mJ in energy, it is possible to visualize a field of 0.5 x1 m. Some results will be reported which have been obtained at the lower surface of an aerofoil, on a wheel well and on an air-brake. Finally a brief review will be made on the improvements envisaged on both the laser and the recording method in order to obtain an operational system for holographic non-destructive testing.
Visualization Of A Subsonic Air Flow Section Using High Speed Holography And Measurement Of The Velocity Field
P. Smigielski, H. Fagot, J. Haertig, et al.
Holograms of the longitudinal section of an air flow traveling at velocities ranging from 10 m/s to 200 m/s have been recorded. The flow section under investigation was visualized with the help of submicron particles which scatter the plane light beam of a pulsed ruby laser. The instantaneous velocities were measured by double exposure with the aid of two pulsed ruby lasers suitably coupled. Results obtained with direct photography (single and double exposure) are also given.
Dependence of exposure time on flow velocity and turbulence for interferograms of heat and mass transfer along a flat plate in a parallel air streamâ€"limits of application of different shutters
Seizo Kato, Fritz Eisfeld
A real-time holographic interferometry is applied to obtain microscopic behaviors of heat and mass transfer in the thin boundary layer along a flat plate in a parallel air stream, in which the physical situation changes instantaneously and spatially. The flat plate is heated or wetted, and is tested in the regimes of laminar and turbulent flows. Interferometric pictures are taken photographically in different exposure times. The obtained results are discussed mainly to find out the dependence of exposure time on free stream velocity and turbulence fluctuation, and to establish practically the optimum expo-sure time with good resolution, under the condition that the temperature and mass concentration gradients change greatly in the thin boundary layer.
Rotating Mirror Camera For Use In Holographic High Speed Interferometry
Fritz Eisfeld
The holographic high speed interferometry makes it possible t1 the structure of turbulent flows, the propagation and the structure of flames 1 and the fast changing temperature fields on pool boiling 2. The rapidity of events and the great number of fringes up to 100 per mm require shortest exposure times. Earlier investigations demonstrated, that a picture of 24x36 mm size using high sensitive photographic material, can be exposed sufficient at an exposure time of 10-6 s. In almost every case a maximum sequence of 100 000 p/s is sufficiant. Other demands are a maximum of resolution and a minimum of optical aberrations. Basing on these results a rotating mirror camera was developed.
Holographic Methods Of Dynamic Particulate Measurements�Current Status
Brian J. Thompson
The field of holographic particulate measurements continues to be very active with many new applications in such diverse fields as bubble chamber recording and contaminant measurements in small vials. The methods have also been extended to measure velocity distributions of particles within a volume, particularly by the application of subsequent image processing methods. These techniques could be coupled with hybrid systems to become near real time. The current status of these more recent developments is reviewed.
Particulate Velocity And Size Measurements Using Holographic And Optical Processing Methods
J. Crane, P. Dunn, P. H. Malyak, et al.
Several methods of applying far-field holography to obtain particle size and velocity measurements are discussed. One method involves forming a double exposure hologram of a particle field whereby the reconstructed image is subsequently studied to yield velocity and size information. A similar technique which involves forming a multiple exposure hologram of a particle field is also evaluated. Finally, a method of measuring particle velocities from the optical Fourier transform of a double exposure hologram is analyzed and experimental results for all three cases are presented.
Microwave Cineholography
V. M. Ginzburg, F. Ya . Nikolajev, B. M. Stepanov
By means of holographic equipment operating in the microwave range, which have been developed earlier and described in the book (1), one can record the holograms of stationary objects.
Three-Dimensional Image Formation By Transformation Of Time Signals Into Spatial Structures
V. M. Ginzburg
Because of the small dimensions of the holograms (expressed in terms of the wave length) and the scale distortions that arise during their optical reconstruction it is practically impossible to produce three-dimensional images of objects when holograms are recorded in the microwave and acoustic ranges.
Multiframe Holographic Shadowgraphy And Interferometry Of Laser Target Plasmas
Garland E. Busch, George Charatis
For purposes of characterizing and studying the formation and evolution of laser driven plasmas in fusion research, a method has been developed to optically probe the plasmas and produce a sequence of four or more holographic time resolved image frames at equivalent rates to 20 billion/sec. The plasma UV probe operates at 0.26 tim either in a shadowgraphic or interferometric mode. Electron density contours between - 1019 and 1021 cm-3 are obtained from the interferograms.
History Of A Certain Holographic Experiment
Grzegorz Kowalewski, Zbigniew Kraska, Romuald Pawluczyk, et al.
The reason of carrying out a special experiment for the purposes of an educational film concerning holography and the preparation of the experiment performed using double pulse holographic equipment have been described. The whole sequence of the chosen phenomenon - the shooting through of an object by a bullet is presented with simultaneous recording of shock waves in the air and deformations of the object. A detailed qualitative analysis of the whole experiment is also given. While working out the final shape of an educational film about holography a problem of finding of a suitable final sequences seemed to be of importance. It is known that the end crowns the work. It was a real problem for us, since the film was meant to provide university students with basic information about holography (its principles, features and possibilities including gas and pulse laser techniques applied to transparent and opaque objects). This film was also intended as a review of main holographic interferometry methods. Thus a sort of summary seemed to be the most desired ending of the film. The spectacular side of the final sequences was equally important. Finally, a Salomonian decision was made to show simultaneously the experiment with phase and opaque objects and the use of double pulse holographic interferometry. We decided to perform the recording of shock waves in the air on the gun bullet and of the deformations of any shot through object.
Application Of High Speed Holography To Measurement Of Particle Size In Flame
Tsuneyoshi Uyemura, Yoshitaka Yamamoto, Naoki Yokoyama, et al.
In order to analyze spray combustion mechanism, it seems to be important to reveal behaviour of fuel spray in flame. Particle size measurement by in-line Fraunhofer holography is widely applied. But few reports have been presented which discuss measurement of particles in flame due to difficulty caused by rapid refractive index variation. In this article, experimental evaluation has been made for measurement accuracy of in-line Fraunhofer holography. And quantitative evaluation has been performed by measurement of spatial intensity distribution in real-image plane. Then holographic interferometry and in-line holography are applied to freeze fuel particle in flame.
Development Of Pulse Holo-Camera For Observation Of Vibration Of Human Eardrum
Tsuneyoshi Uyemura, Naoki Yokoyama, Yoshiyuki Ohba, et al.
For the purpose of observing the vibration of the human tympanic membrane clinically, a holocamera was test designed and manufactured. At the stage of test design, an experiment revealed the deterioration of laser light in its coherency when it came out through the optical fiber. As the method of improving the deteriorated coherency, two laser beams both of which were passed through the optical fiber bundle, were used for the illumination beam as well as the reference beall under a certain condition. This procedure made possible to manufacture a pulsed holo-camera well suitable for the clinical use
Observation Of Firing In Four-Cycle Internal Combustion Engine Model By High Speed Photography And Holography
Tsuneyoshi Uyemura, Icho Fu, Yoshitaka Yamamoto, et al.
In this article 4-cycle internal combustion engine model was chosen as an object, and combustion in that engine was visualized and recorded by various techniques including real-time holographic interferometry. Rotating prism type high speed camera was used as record ing device, and then combustion in the engine model was observed under various environmen tal conditions. As the environi,ental conditions, quantity of load to engine, kind of fuel and ignition timing was varied to samie extent.
Observation Of Laser Machining Process By High Speed Holography
T. Uyemura, S. Ozono, Y. Yamamoto,, et al.
High speed holography has been successfully utilized in observation of pulsed laser machining process. High speed holography is very powerful in recording high speed phenomena accompanied with strong self-luminance, as seen in the process of pulsed laser machining. In this paper, it is shown that vertical sectional shiape of drilled hole and splashed parti cles of molten metal in machining process could be recorded by using off-axis and in-line holography. From experimental results, many of the new aspects of laser machining process have become clearer.
Flash X-Ray Studies Of Ballistic Phenomena
Edwin A. Webster Jr.
Frankford Arsenal was a pioneer in the development and application of flash radiography of ballistic phenomena. Frankford Arsenal first began using the Westinghouse Micronex flash X-ray system in 1941, and converted to Field Emission Corporation (now Hewlett-Packard) flash X-ray equipment in the early 1960's. When Frankford Arsenal closed in 1977, its missions and equipment were transferred to U.S. Army Armament Research and Development Command. The flash X-ray studies performed at Frankford Arsenal are now being continued at the ARRADCOM Test Site, Fort Dix, New Jersey as well as at ARRADCOM Headquarters, Dover, New Jersey. These studies are concerned with investigations of small caliber ammunition and weapons, and reduced scale models of large caliber projectiles. The important feature of flash X-rays in ballistics research and development is that high speed radiographs provide qualitative and quantitative information which frequently cannot be obtained by any other means or which can be obtained more easily and inexpensively by this technique. This paper describes some of the experimental applications of high speed radiography in obtaining data on various ballistic phenomena such as the determination of projectile penetration of armor plate, and particle size and orientation after penetration.
Flash X-Ray Cineradiography At 100,000 Fps
J. J. Trimble, C. L. Aseltine
We have developed a cineradiography technique which will produce six pictures, each on a separate piece of film, with framing rates up to 100,000 frames/second. The system utilizes six 150 keV flash x-ray tubes mounted side by side in one head. X-rays are converted to light by a single x-ray image intensification'screen with rapid phosphor decay. The x-ray screen is viewed through six individually adjustable lenses by six, gated image intensifier tubes with light amplication of 15,000. Output from the tubes is recorded on Polaroid film. The x-ray flash duration of 70 nanoseconds per tube determines exposure time.
Three-Frame Flash X-Radiography System For Ion Beam Pellet Implosion Studies
J. Chang, D. L. Fehl, L. Baker, et al.
A high resolution three-frame flash x-radiography (FXR) system has been developed for studies of intense ion beam driven Inertial Confinement Fusion pellet implosions. This system consists of three independently triggered micro-point [ ~100 4m spot size] FXR sources and three lead shielded collimating cameras. Each of the FXR sources has a 3 ns output pulse that is characteristic of a 600 keV tungsten bremsstrahlung spectrum. The sources and the cameras are arranged with equal azimuthal angular spacing on a 12° half angle biconic surface. With this system, three time-separated and 3X magnified x-radiographic images of the imploding target with 100 p.m spatial resolution and 2.6 ns temporal resolution can be made. Targets moving as fast as 3-4 cm/4s can be recorded without motion blur. Studies of high Z metallic spherical and cylindrical targets imploded by an intense ion beam have been carried out. Results show that ablatively driven puher velocity as high as 1 cm/4s can be achieved with an ion beam intensity of 0.5 TW/cm on target.
Stable Slow Liquid Shock Wave In Waveguides
R. Germer
Wire explosions in 2 mm or 4 mm thick layers of H2O contained between a plate of 10 mm lucite and a thin metal plate (some 0.1 mm thick) are studied by X-ray flash photography. A slowly propagating onedimensional liquid wave is induced. Its formation and propagation can be studied with these pictures. The slow propagation velocity is explained by its surface-wave character and a vortex, both explored for the first time. The formation of cavitations in the surrounding liquid is seen, too and proofs a presumption used to explain earlier experiments. The cavitations interact with the shock waves and cause interesting features. Depending on the experimental condition the cavitation bubbles are formed chaotic or in periodic patterns These experiments could be a test for modern theories relating turbulence and chaos.
Proposed System For High Speed Materials Testing Of Microtargets Under Dynamic Load Using Flash X-Ray Diffraction (FXD) Analysis
Peter Krehl
Flash X-Ray Diffraction (FXD) is a method of high potential to study lattice compression and phase transformations in shock-compressed matter. The technique commonly applied records a back reflection diffraction pattern at the back side of the target, while its front side is struck by a projectile. However, since the experimental time window for recording is very narrow, only low-atomic number materials could be investigated successfully. The extension to materials of higher density would be of substantial practical interest, as well as a simulation of longer lasting loading histories in the microsecond regime. Furthermore, since only a small target volume is necessary for FXD diagnostics, a miniature compression method rather than conventional impact methods would be more adequate, in regard both to tube and film protection, and usable x-ray energy. The present paper discusses a pulsed, linear magnetic pinch technique for micro-target compression and possible applications in a Debye-Scherrer FXD setup.
Streaked X-Ray Microscopy Of Laser Fusion Targets
Robert H. Price, E. Michael Campbell, Mordecai D. Rosen, et al.
An ultrafast soft x-ray streak camera has been coupled to a Wolter axisymmetric x-ray microscope. This system was used to observe the dynamics of laser fusion targets both in self emission and backlit by laser produced x-ray sources. Spatial resolution was 7 pm and temporal resolution was 20 ps. Data is presented showing the ablative acceleration of foils to velocities near 107 cm/sec and the collision of an accelerated foil with a second foil, observed using 3 keV streaked x-ray backlighting. Good agreement was found between hydrocode simulations, simple models of the ablative acceleration and the observed velocities of the carbon foils.
High Speed Motion Neutron Radiography Of Dynamic Events
A. H. Robinson, R. H. Bossi, J. P. Barton
This paper describes the development of a technique that enables the neutron radiographic analysis of dynamic processes over a period lasting from one to ten milliseconds. The key to the technique is the use of a neutron pulse that is broad enough to span the duration of the brief event of interest and intense enough to permit recording of the results on a high-speed movie film at frame rates up to 10,000 frames/second. A system has been developed which utilizes the pulsing capability of the OSU TRIGA reactor. The system consists of the Oregon State University TRIGA reactor (pulsing to 3000 MW peak power), a neutron beam collimator, a scintillator neutron conversion screen coupled to an image intensifier, and a 16 mm high speed movie camera. The peak neutron flux incident at the object position is approximately 4 x 1011 n/cm2s with a pulse, full width at half maximum, of 9 ms. The system has been operated in the range of 2000 to 10,000 frames/second and has provided high-speed-motion neutron radiographs for evaluation of the firing cycle of 7.62 mm munition rounds within a steel rifle barrel. The system has also been used to demonstrate the ability to produce neutron radiographic movies of two-phase flow.
Investigation Of Other Operating Points For The RCA Streak Tube In The Lawrence Livermore National Laboratory Streak Camera
S. W. Thomas, R. L. Peterson, R. L. Griffith
The RCA streak tube can be operated satisfactorily at voltages other than those we have been using for nearly ten years. Our soft x-ray streak camera uses the RCA C73435 streak tube body fitted with a removable x-ray cathode. The front of the streak tube is exposed to the vacuum of an experimental chamber, which is not entirely under the control of a streak camera operator. Occasionally, the vacuum becomes poor enough to cause corona and arcing from the cathode to the chamber wall. The corona problem is more difficult because the dimensions of the x-ray camera body are smaller than for the optical camera body. Therefore, we investigated the effects on camera performance of decreasing the accelerating voltage at the cathode from the customary 17 kV. Several operating points were evaluated and 12 kV cathode-to-anode with 5 kV cathode-to-grid were selected for more detailed investigation. Transverse spatial resolution and dynamic range were found to be essentially the same as at our normal operating point of 17 kV for the cathode and 2500 V on the grid. Magnification, sweep linearity and absolute sensitivity changed as expected. In the course of the investigation, we measured the dynamic range with our CCD readout system. The effect of coulomb repulsion at the crossover point was also measured and found not to affect dynamic range.
Betatrons For Investigation Of Rapid Processes And Testing Moving Gears Inside Closed Housings
D. A. Boiko, V. A. Moskalev, V. L. Chakhlov, et al.
High-current 25-1AeV betatrons with cinecameras can be helpful in studying concealed processes proceeding at a rate of up to 3 kms. An installation comprising a small betat-ron with a synchronization circuit has been devised for inspection of machine elements moving periodically at a frequency of up to 200 Hz. These elements can be placed in housings having walls of a thickness equivalent to 300 mm of steel.
Photoelectron Emission From X-Ray Photocathodes Intended For Picosecond Streak Tubes
V. K. Chevokin, A. M. Prokhorov, V. N. Schemelev, et al.
It is shown that various metallic-type photocathodes when irradiated by soft X-ray emis-sion in the 1-10R energy range, have the energy distribution of secondary-emission photoelectrons only in the range of 4-7 eV(FWHM). The latter value for dielectric-type photocathodes (KC1 and NaCl) is even less and lies in the region between 1.5-2.5 eV. Furthermore, the quantum efficiency of these, dielectric-type photocathodes is almost five times higher than for the metallic ones in the same spectral range. Taking into account the rejection of pho-toelectrons with energy higher than 50 eV (although the "tail" in photoelectrons energy distribution spreads up to several keV) in image formation process, one can conclude that application of dielectric-type photocathodes for picosecond X-ray treak tubes looks very promising.
Measurement Of Very High Masses Per Unit Area In A Flash X-Rays Experiment Calibration Problems
Jean-Pierre Gauthier, Rene Guix
We describe the calibration method of a radiography giving the relation between the optical density (OM and the thickness of iron the rays have been passing through. We discuss -Op results obtained with the GREC flash X-ray generator which permits to measure surface masses up to 130 g x cm'. The scattered light is avoided by a multihole collimator. The perturbation of the calibration steps, by extra moving materials, is taken in account by a supplementary measure which permits to evaluate them.
Absolutely Calibrated Soft X-Ray Streak Camera For Laser Fusion Applications
Robert L. Kauffman, Gary Stradling, Hector Medecki
We have calibrated, the intensity output of a soft x ray streak camera (SXRSC) in order to make absolute flux measurements of x rays emitted from laser-produced plasmas. The SXRSC developed at LLNL is used to time-resolve x-ray pulses to better than 20 ps. The SXRSC uses a Au photocathode on a thin carbon substrate which is sensitive to x rays from 100 eV to greater than 10 keV. Calibrations are done in the dynamic mode using a small laser-produced x-ray source. The SXRSC is calibrated by comparing its integrated signal to the output of calibrated x-ray diodes monitoring the source strength. The measured SXRSC response is linear over greater than two orders of magnitude. Using these calibrations, absolute intensities can be measured to an accuracy of +30%."
Soft X-Ray P 550 Streak Camera: Characteristics And Applications
C. Cavailler, N. Fleurot, J. Launspach, et al.
This paper presents the latest performances of our P 550 X soft X-ray camera for laser fusion applications. This instrument is sensitive to photon energies down to 100 eV and has the same spatio-temporal performances than standard X-ray streak cameras.
P 600/650 X-Ray Streak Camera With Optimized Spatio-Temporal Resolution
B. Boutry, C. Cavailler, N. Fleurot
This paper presents the latest performances of the P 600 X-ray streak camera designed for laser fusion experiments. It reaches very high performances in the 1.5 to 10 keV range : 16 to 20 Zp.mm- for the maximum sweep speed which corresponds to a 2 ps theoretical time resolution. We discuss its adaptation to the soft X-ray spectral range down to 100 eV.
High Speed (<250 ps) High Gain X-Ray Shutter Camera
N. Fleurot, J. P. Gex, M. Rostaing, et al.
A high speed X-ray shutter tube has been developed for laser induced plasma imacing. The liiritinn exposure time is in the 250 ps range and 5 images can be recorded on the same laser shot, in order to provide a 5 spectral channel analysis of the plasma. A high light gain is obtained from a microchannel plate inserted in the 50 transmission line, which provide the adapted structure to reach such a time exposure. We present the main performances of this camera.
Re-Evaluation Of The Temporal Response Of Csl Photocathodes
G. L. Stradling, D. T. Attwood, R. L. Kauffman
The optimization of photocathodes for ultra-fast x-ray detectors is an area of active interest in the x-ray diagnostic community.1-9 New evaluations of CsI and Au transmission-photocathodes in side-by-side in situ streak camera measurements are discussed here. Temporal response of the two materials and sensitivity comparisons over a wide range of thicknesses are presented.
Ultrashort X-Ray Probe Backlighting For Implosion Fusion Experiments
C. Yamanaka, N. Miyanaga, K. Imasaki, et al.
Two X-ray backlighting techniques have been developed to diagnose the laser-imploded fusion targets. One is the multi-color backlighting for the targets consisting of various materials. The implosion dynamics of a double shell target, which consisted of a parylene outer shell and a glass inner shell, was investigated by using 1.2 keV and 2.6 keV X-ray source and a couple of pinhole cameras. The other is the application of a point X-ray source to the plasma diagnostics. It has many advantages in comparison with the usual back-lighting with a extended source. The new backlighting methods were tested through (1) a simple backlighting without any X-ray optics, (2) the measurement of X-ray refraction due to steep-gradient, high-density plasma, and (3) the spectrally resolved backlighting of planar targets combining with a flat crystal spectrometer.
Spectrally Resolved Flash X Radiography Of Laser Accelerated Targets
Robert R. Whitlock, Stephen P. Obenschain, Jacob Grun, et al.
The physics of the acceleration of planar foils to high velocities by laser-driven ablation is being studied for the inertial confinement fusion application. The motion and density of these foils was studied by spectrally resolved flash x radiography, using an imaging crystal spectrograph. These results will be compared to our earlier flash x-ray studies using pinhole camera imaging, which does not afford spectrally resolved images.
Image Enhancement Applications At The Lawrence Livermore National Laboratory
R. E. Twogood, R. J. Sherwood, M. R. Portnoff
A diverse set of digital image processing applications exists at the Lawrence Livermore National Laboratory. While many of these include some sort of image analysis or restoration, virtually all of them require image enhancement procedures. In this paper we describe the principal image processing facility at the Laboratory, followed by a discussion of several of the major image processing application areas.
Omnidirectional Real Time Imaging Using Digital Restoration
R. L. Anderson, N. Alvertos, E. L. Hall
Image processing techniques are being developed for geometric and blurring restoration of fish-eye lens images. The history of extreme wide angle imaging is briefly reviewed. A method for geometric restoration of such distorted images is derived, based on a simple pin-hole camera model. In a more detailed examination of the model it is shown that the fish-eye image can be transformed from a space variant system to a space invariant one. An example is given of the application of this transformation to "undistort" a photograph made through a fish-eye lens. After geometric restoration, the image can be further enhanced by applying debluring techniques to improve resolution. An example is given of the result of deblurring applied to the geo-metrically restored image from the previous example.
Processing In Real Time And In Differential Time Of Low Contrast Images
P. Nouge, J. C. Miquel
In 1981, the Centre d'Essais des Landes (CEL) installed a new processing system for low contrast images on the 35 mm film taken with cinetheodolite or high speed cameras. This new processing system includes two main parts: one, called TELEPIMS, is a video system that is used to simulate and evaluate the improvements capable of being produced and to choose the parameters to use on the second part called TACITETireuse a Amelioration delContraste des Images par TraitementlElectronique which means "optal printer with improvement of image contrast by an electronic system." This new machine allows the printing of the images with an analog process on a copy film compatible with the film readers. Some results will be presented.
Sensitization And Performances Of SI Image Converter Tubes Designed For Laser Fusion Experiments
F. Gex, R. Alexandre, D. Bauduin, et al.
S1 streak cameras with time resolution beLter than 10 ps are now currently available at the Centre d'Etudes de Limeil. They integrate a standard P 500 image converter tube slightly modified to allow the S1 photocathode's deposition. Almost 70 % of the tubes have 1.06 μm sensitivity greater than 50 pA/w and 60 % are in the 100 to 400 μA/w range. It is also possible to regenerate the 1.06 pm sensitivity when necessary, thus solving the difficult lifetime problem of these tubes. Dynamic range of a few hundreds is possible for 47 ps I.R. laser pulses and more than 64 for 12 ps pulses.
Metal Combustion In High Pressure Oxygen Atmosphere: Detailed Observation Of Burning Region Behavior By Using High Speed Photography
Kenji Sato, Yoshiko Sato, Takao Tsuno, et al.
Detailed process of upward fire spread along a mild steel cylinder in high pressure oxygen has been studied by using high speed photography. Fire spread experiments were conducted in a cylindrical, high pressure oxygen chamber of a capacity of about 2.5x107 mm3. The movement of a molten mass attached to the bottom end of a burning steel cylinder and that of a molten mass droplet detached from the bottom end were recorded by a 16 mm or 35 mm high speed cinecamera and analyzed. By analyzing the oscillatory behavior of the molten mass droplet, its main component was inferred to be iron oxide. The local spread rate fluctuation was observed during a period of the overall cyclic behavior. Based on the location of the observed high luminosity region and surface flow of the molten mass, convection was inferred to be a dominant mode of heat transfer at the molten-solid boundary and the fluctuation of the local spread rate was supposed to be attributable to the nonuniformity of the convective heat transfer at the molten-solid boundary.
Strong Biological Radiation Damage With X-Ray Flashes
R. Germer, J. Jakschik
The influence of X-ray Flashes on the germinative faculty of cress seeds has been studied. The experiments show that the radiation damage produced by X-ray flashes (τ < 0,5 μs) is much stronger than the influence of continuous radiation if the absorbed dose is the same. With a dose of about 0.3 Gy, it is possible to reduce ther germinative faculty from 99 % to 85 % while the same dose of continuous radiation shows no significant influence on the growth process. The result indicates that short soft X-ray flashes with high intensity are particularly important in the production of biological defects and should be considered in radiation protection.
Use Of Tv-Frame Memory On Electronic Speckle Pattern Interferometry Applied To Orthopaedics
O. D.D. Soares, A. L.V.S. Lage
An automatic image digitizer has been developed to operate on the observation of transient phenomena in real time to the study of orthopaedics systems. The image of the speckle pattern corresponding to the combination of illuminating pulses is recorded in the solid state frame store. The stored electronic image is then automatically subtracted from a sub sequent image corresponding to the second pulse set. The live fringes appear on the monitor and are video recorded for later evaluation. Other operation modes can equally be realized with the Tv-frame memory. Real time hologrammetry can also be performed within the correlation range. Benefits can be acquired in moire techniques utilizing the proposed memory.
Hologrammetric Interferometry In The Study Of The Leg-Foot Biomechanical System
O. D.D. Soares, A. L.V.S. Lage
The knowledge of physiological loading is necessary for the analysis of different osteosynthetic devices. Surgical procedures also rely on the assumption of the real loading conditions of the human biomechanical system. The ultimate aim of the work is to describe the stress distribution in the leg-foot system by hologrammetric interferometry with the necessary contribution from other biomechanical methods, and to evaluate the mechanical role of the biomechanical elements of the locomotor system following previous work by several authors. The talus surface deformation is described by double-exposure hologrammetric interferometry and pertinent discussion of anatomical and clinical as surgical aspects is acomphished. The perspectives of the achieved results directing future objectives are presented in view of the ultimate aim of the research project.
Investigation Of Vapor Explosion Mechanisms Using High Speed Photography
Donn R. Armstrong, Richard P. Anderson
The vapor explosion, a physical interaction between hot and cold liquids that causes the explosive vaporization of the cold liquid, is a hazard of concern in such diverse industries as metal smelting and casting, paper manufacture, and nuclear power generation. Intensive work on this problem worldwide, for the past 25 years has generated a number of theories and mechanisms proposed to explain vapor explosions. High speed photography has been the major instrument used to test the validity of the theories and to provide the observations that have lead to new theories. Examples are given of experimental techniques that have been used to investigate vapor explosions. Detailed studies of specific mechanisms have included microsecond flash photograph of contact boiling and high speed cinematography of shock driven breakup of liquid drops. Other studies looked at the explosivity of various liquid pairs using cinematography inside a pulsed nuclear reactor and x-ray cinematography of a thermite-sodium interaction.
Dynamical Properties Of Impacted Target By Using Laser Doppler Velocity Interferometer (Ldvi)
Jai Ki Kim, Sang Soo Lee
A laser Doppler velocity interferometry for measuring the velocity of reflecting free surface is developed and applied to the investigation of the bulging properties of a steel target. The instantaneous free surface motion of the target impacted by a steel projectile driven to 25.6m/sec by shock wave, is observed by using a laser Doppler velocity interferometer. The measuring time is synchronized with the impact time by using a trigger pin. As the projectile with the flat elivated nose approaches to the target, the trigger pin first makes contact to the projectile and at the instant of the impact, a signal pulse for triggering oscilloscope is genetated. Initially thick targets (1.2 - 2.4cm) are used for the measurement of the elastic motion of the free surface, and their maximum velocities are measured. In the thinner target, the free surface gets bulging plastic deformation. Its maximum bulging velocity, which depends on the thickness of the target, is measured for thickness 0.5 - 0.8cm. It is found the maximum bulging velocity decreases approximately inversely with respect to the thickness of the target. The time and target thickness dependence of bulging deformation of the mild steel is determined for the constant impact velocity. The parameters in Bingham's form of shearing force are also determined from the thickness dependent maximum bulging velocities.
Fast Large Aperture Camera For Very High Energy Gamma Ray Astronomy
D. J. Fegan, D. McLaughlin, J. Clear, et al.
The 10 m optical reflector on Mount Hopkins in southern Arizona has been converted to a two dimensional imaging detector using an array of fast phototubes. The images of interest are the Cherenkov light generated by small cosmic ray and gamma ray showers in the earth's atmosphere. Fast digitisation techniques are being used to give a 37 pixel image of each shower (full field of 3.50). Since the showers arrive at random times the camera must be triggered by the light signal. The minimum resolving time (integration time) will be 10 nsec but the camera may also be adapted to study slower pulse phenomena The primary purpose of the camera will be high energy gamma ray astronomy in the 1011-11 eV region.
Schlieren Photography-Review, Applications, And Bibliography
T. P. Davies
A brief description of the principle of Schlieren Photography is given followed by a review of possible systems and variations in technique. A Multiple Source Schlieren System of large aperture is described with some recent applications. The bibliography includes over 140 references to the major systems modifications and a variety of applications.
Some Theoretical And Designing Problems In Optical Systems Of High Speed Cameras With Optical-Mechanical Commutation
A. V. Belinskiy
Modern science requires more detailed and thorough study at experimenting with a large variety of high-speed processes.1 That is why the most important things, in developing high-speed photorecord methods and devices, are improving photorecorded image quality and designing new cameras with improved optical system characteristics for this purpose.
2000 Fps Solid-State Image Sensor
T. H. Lee, T. J. Tredwell, B. C. Burkey, et al.
We describe a very high-speed image sensor for image recording at up to 2,000 full or 12,000 partial frames per second. The sensor consists of a 192 V x 248 H array of photo-capacitors. For high-speed operation, the image-sensing area is divided into six blocks, each block having 32 parallel outputs. The blocks are addressed sequentially, and the 32 outputs are sensed simultaneously. The sensor dynamic range is 46 dB at 2,000 fps. Spectral sensitivity, noise, and spatial resolution are discussed.
Application Of Photosensitive Material For Deformation And Vibration Analysis Of Structures Using Objective Laser Speckles
F. P. Chiang, C. C. Kin
By illuminating a ground glass with a laser beam, a spatial field of speckles is created. These speckles are used as surface strain or displacement gauging elements of structures under static and vibrational deformation by coating the structural surface with photosensitive material. Equations used in obtaining the strain and displacement are shown.
Frequency Method Of Photometric Measurements In X-Ray Pulse Radiography
S. P. Vavilov, A. I. Leshchenko
In recording high-speed processes photograpnic and electrographic films are of great importance. The quality of images is characterised by a number of parameters, the main of them being contrast transfer function and resolution. In most cases X-ray images of high-speed processes have poor contrast, which in its turn negatively affects resolution. To improve informability of images of poor contrast it was proposed to use phase-frequency processing of X-ray pictures. A device for phase photometering is described and its merits are discussed in this paper.
Recording Of High Speed Processes In The Infrared Region
V. S. Doev, Yu. A. Drozhbin, I. G. Gorlova, et al.
In spectroscopic and in particular, laser investigation of kinetics involved in fast processes and in many other scientific and technological applications, wide spectrum radiation receivers are often helpful. What is needed in spectrographs and optomechanical cameras for recording high speed processes (HP) are receivers of areas ranging from tens of square centimenters to square meters.
Study Of Errors Brought By Camera Vibration And Their Influence To The Determination Of Target Performance
Tung Cheng, Ching-Wu Lin
The paper deals with the method to find out the frequency and amplitude of the vibration brought by running mechanical cameras, and the result has been analyzed by mathematical techniques. It describes the significant errors involved and offer specific guidelines for camera manufacturing and data processing consideration.
Error Analysis Of High Speed Camera By Interferometer, Laser Reflected Spot, And Testing Chart Method
Rong-Seng Chang
The error analysis of high speed camera by interferometer, laser spot and testing chart method is described. The test chart is for testing total vibration. Interferometer is for testing ground vibration, in order to reduce the sensitivity of fringe, an inclination of of mirrow are introduced. Laser spot method is used for double check the result. Further improvements for each method are suggested.
Measuring The Flutter Of Plane Model With Dynamic Shadow Moire Topography
Wu Minda, Ni Shuhue
This paper describes an optical method for measuring the flutter of plane model with dynamic shadow Moire topography. The formulas of calculations are offered, its errors are discussed and the method of th test, arrangement device are also stated in the paper. The curves of "position-amplitude" and "time-amplitude" are shown. The results of the measurements are compared in accuracy with the electric method using acceleration sensor. Both are very approximate.
New Method Of Measurement Of Dynamic Young's Modulus By High Speed Moire Topography
Takao Tsuno, Yoshio Nakamura
The deformation process of a simply supported beam, made of polymethylmethacrylate (PMMA) or polystyrene (PS) which is a kind of synthetic polymer, was recorded by high speed Moire topography with a time resolution of one microsecond and a contour sensitivity of 0.22 mm. As an interpretation of the Moire contour lines, a new method of the measurement of dynamic Young's modulus was discussed from theoretical point of view. As the experimental results based on the new method, the dynamic Young's modulus of PMMA- or PS-plate increased in proportion to the impact-speed in the range from 10 to 30 meters per second.
Measurement Of Time Resolution For Rotating Mirror Streak Cameras
Chen Junren, Wang Shuicai, Shi Ke, et al.
Time resolution is one of the important performances of rotating mirror streak cameras. Therefore, it is necessary to measure the performance of this kind of cameras in practice. This paper describes a new method using a series of light pulses and a optical delayer. The light pulses generated by a YAG mode-locked laser with a frequency multiplier have wave length of 530nm and the pulse duration about 30ps. With this method, the time resolution of ModelZSK-29 rotating mirror streak camera was measured. When the width of slit is 0.025mm and the rotating speed is 7000rps, the time resolution of the camera is equal to 2.4ns.
Multiprofile-Streak Technique
Manfred B. Held, Peter P. Nikowitsch
Streak technique signifies stretching out, in terms of time, a _process under observation, generally along a line. Here the event under observation is imaged vbia the main lens to the slit of the streak camera. Only the image of the narrow strip of the event which camera lens and the rotating mirror on the film plane. on rotating of the mirror, a chronological record is retained, spatially stretched, on the film according to the speed of the camera.
Optoelectronic Measurement Of Projectile Velocity And Profile Graphing With The Aid Of A Single Light Barrier
K. Sterzelmeier
An optoelectronic method is described which is used for the simultaneous measurement of the projectile velocity and contour with the aid of only one light barrier. A measuring laser produces a very thin lighting row perpendicular to the trajectory. The time-dependent luminous flux is recorded using a pin diode mounted in the transmitted light beam. The velocity is determined as a quotient from the length of the projectile and its residence time in the lighting row. The luminous flux is proportional to the projectile contour, so that the profile can be reconstructed. Data are recorded with a 10 MHz-transient data logger. A device based on the aforementioned principles has already been tested with success.
Interactive X-Ray And Particle Image Processings (Ixpip) In The Inertial Confinement Fusion Experiments
M. Yamanaka, H. Niki, Y. Yamamoto, et al.
Two-dimensional images by X-rays or particles in the inertial confinement fusion (ICF) experiments are digitally processed in a short period of time. Using a minicomputer image processing system, we find that such digital image processings as local average, gray scale transformation, level slice, two-dimensional intensity profile display, histogram equalization and pseudo-color display are useful for those ICF images. And, tomographic features of URA (uniformly redundant arrays) camera are investigated by computer simulation. According to calculation, URA camera will be useful for plane-like or small targets because of its brightness and high S/N.
Galatea�An Interactive Computer Graphics System For Movie And Video Analysis
Michael J. Potel, Steven A. MacKay, Richard E. Sayre
Extracting quantitative information from movie film and video recordings has always been a difficult process. The Galatea motion analysis system represents an application of some powerful interactive computer graphics capabilities to this problem. A minicomputer is interfaced to a stop-motion projector, a data tablet, and real-time display equipment. An analyst views a film and uses the data tablet to track a moving position of interest. Simultaneously, a moving point is displayed in an animated computer graphics image that is synchronized with the film as it runs. Using a projection CRT and a series of mirrors, this image is superimposed on the film image on a large front screen. Thus, the graphics point lies on top of the point of interest in the film and moves with it at cine rates. All previously entered points can be displayed simultaneously in this way, which is extremely useful in checking the accuracy of the entries and in avoiding omission and duplication of points. Furthermore, the moving points can be connected into moving stick figures, so that such representations can be transcribed directly from film. There are many other tools in the system for entering outlines, measuring time intervals, and the like. The system is equivalent to "dynamic tracing paper" because it is used as though it were tracing paper that can keep up with running movie film. We have applied this system to a variety of problems in cell biology, cardiology, biomechanics, and anatomy. We have also extended the system using photogrammetric techniques to support entry of three-dimensional moving points from two (or more) films taken simultaneously from different perspective views. We are also presently constructing a second, lower-cost, microcomputer-based system for motion analysis in video, using digital graphics and video mixing to achieve the graphics overlay for any composite video source image.
Digital Processing Of Images For Space-Variant Systems
A. M. Aganov, V. A. Medvedev, B. M. Stepanov, et al.
In non-coherent image formation optical systems with the space-variant point scattering function (pulse response) the image with linear distortion may be represented by the following model = Where h(x,y,x',y'), f(x',y') and n (x,y_ are the pulsge response, the intitial image and the additive noise, respectively.
Optical Data Processing With The Transformation Of The Laser Radiation Spatial Coherence
A. M. Zarubin, A. I. Larkin, A. A. Markilov, et al.
Methods of optical data processing based on the transformation of the degree of spatial coherence (DSC) are considered. The methods described are characterized by high speed processing and reduced sensitivity to phase noise and to accuracy of optical elements alignment.
Troll Accelerator�An Installation For Calibration Parameters Of High Speed Photorecorder
S. I. Anevsky, V. S. Panasyuk, B. M. Stepanov
The paper describes the operating principles and design features of the "Troll" strong magnetic field synchrotron which is used as a generator of picosecond synchrotron radiation pulses. The results of using the synchrotron in the calibration of high speed photorecorder parameters are summarized. The operating principles and main parameters are described of the "Troll"-based electron accumulator which is now assembled for the continuous generation of picosecond synchrotron radiation pulses. The possibility of improving the intensity of such pulses by collecting the radiation from the full bunch orbit by using dedicated reflectors is also discussed.
Equidensitometric Methods In An Evaluation Process Of A Film Record Of A Switching Arc
Bohuslav Svejda, Boleslav Gross
A high speed cinematography is also one of useful and fruitful methods of optical plasma diagnostics. Value levels of informations obtained from a film record can be very different; this fact depends very much on a used evaluation process. An equidensitometrical investigation is a suitable method for an increase of the information capacity and it presents a possibility how to obtain more valuable informations. Two ways directing to the acquirement of equidensitometric maps were used in our work: a wet photographic process using the Sabattier effect and an electronic device constructed for the special purpose. Some results obtained by these both evaluation methods are compared and discussed.
Image Processing Techniques Applied To Numerical Stacking, Homogeneity Of Matter, Automatic Tracking Of Traces And Contours
Jacques-Gaston Lefebvre, Jean-Pierre Gauthier
We shall present, in this communication, some important applications of image processing techniques. Before this, we briefly describe, the two principal parts constitutive of the laboratory : - the digitalization part, and - the visualization and treatment part, as shown on figure 1
Measurement Of Velocity And Shape Of Small Hypervelocity Projectiles In A Plasma Accelerator
B. Schroeder, E. Igenbergs, H. Kuczera
Small projectiles are accelerated to velocities between 10 and 20 km/sec in the plasma-accelerator of the Lehrstuhl f iir Raumfahrttechnik, Technische Universitat MUnchen. A technique has been developed to measure the velocity and the shape in the plasma environment. The system consists of a light barrier generated by the multiple reflection of a laser beam between two mirrors. The light reflected by the projectiles when these cross the laser beams is detected by a photomultiplier. The time needed for the projectile to reach the position of a laser shadowgraph device and the trigger signal for the camera are provided by a computer. The development of this photographic system as well as experimental results are discussed.
Flight Characteristics Of A Rocket Under Various Environmental Conditions
Yutaka Tashiro
This paper describes the flight characteristics of rocket under the various environmental conditions, especially the wind effect on the flight of rocket during burning. 280 rounds of small solid propellant free rocket were fired, and the coordinates and height of burnt out point on the trajectories were recorded by means of Cinetheodolite. The results of theoretical and experimental study showed that the wind effects of rocket during burning could be able to compute introducing an empirical factor T (Tashiro's factor) into the equations of motion as particle.
Computer Evaluation Of Coulomb Repulsion Effects In Picosecond Streak Image Tube
V. P. Degtyareva, V. N. Platonov
The computer technique for evaluation of Coulomb repulsion effects in picosecond streak image tube has been investigated. This technique is intended to more precise calculation of the dynamic range of electron-optical streak cameras. The developed procedure simplify calculations of the shape distortion of picosecond light pulses having arbitrary intensity pro-files when the latter being recorded on the image tube screen. These calculations were adopted for evaluation of Coulomb repulsion effects in PVOO1 streak image tube.
Hubert Schardin: His Work And His Influence On Modern High Speed Physics And Photonics
K. Vollrath
With the 15th International Congress on High Speed Photography and Photonics, the history of these meetings covers a time interval of 30 years. Within this time, about 1200 scientific papers have been presented. Assuming that each paper requires at least 6 months ©f experimental work, one scientist had to work for 600 years to fulfil this tremendous work, and if in our imagination this scientist had begun his work e.g. at MIT in 1492 when Columbus discovered this continent, he would have been still at work today. From this point of view the importance of our meetings is obvious.
15Th International Congress On High Speed Photography And Photonics San Diego 1982
James A. Dunne
This presentation traces the evolution of techniques and results of deep space mission imaging experiments over the past two decades. It is a story of rapidly developing capabilities, starting with tiny snapshots of the primeval face of Mars and culminating in dazzling color portraits of the complex and beautiful rings of Saturn. In between, a rich legacy of images was returned from spacecraft variously flying by, crashing into, orbiting or landing on the moon, Mercury, Venus, Mars, Jupiter, Saturn, and the many satellites of the two giant planets. Spacecraft, optics, detectors, electronics, scan platforms, telemetry transmitters, giant receiving antennas, and a variety of computers comprise the technology of this odyssey.