The operating principle of a new picosecond electronic framing camera has been experimentally verified using a trial tube which can obtain one frame image on the output screen. In one mode, sinusoidal wave voltage of the frequency of u 86 MHz has been applied to a deflection plate of the tube similar to synchroscan streak tube. The exposure time of ~ lns has been obtained. In the other mode, push-pull ramp voltage has been applied to a pair of deflection plates. In this case, the exposure time of % 110 ps has been attained.

The construction of a low impedance and high intensity flash x-ray (FX) generator for biomedical radiography is described. This generator consisted of the following components: a high voltage power supply, a low impedance transmission line with a high voltage coaxial condenser (120kV-0.15μF), a compressed-gas (SF6) gap switch with a small-sized trigger device operated by light through a fiber, a trigger delay device, a vacuum pump system, and two evacuated FX tubes, each of a different type, with eight coaxial cables. The FX generator may be used for condenser charging voltage of 50 to 120kV. The electric pulse width of the FX output varied according to the beam quality, anode-cathode (A-C) space, and others, and ranged from 0.1 to 0.4μs. The original FX intensity from the source was determined by the condenser charging voltage and A-C space, and the maximum intensities of the Type A and B tubes were about 100 and 200mR at lm/pulse, respectively. The FX quality was determined by the average voltage of FX tubes, the efficiency of electron beam conversion into FX due to the configuration between the anode and cathode electrodes, and the insertion of metal filters. The effective focal spot varied due primarily to the configuration of electrodes and the insertion of filters. Various clear FX images achieved with a digital radiography system were obtained by controlling the FX intensity, the quality, and the size of the effective focal spot.

The flash energy subtraction technique, its principle of operation, and the control methods concerning the FX spectrum distribution are described. This technique was performed by using a high intensity soft flash x-ray (FX) generator having spectrum control functions, Fuji computed radiography (FCR) achieved with a subtraction function, a thin metal filter of copper, and two or three imaging plates. The FX generator was a single exposure type and consisted of the following components: a high voltage generator, a simple low impedance coaxial transmission line with a high voltage coaxial condenser (0.2μF, 100kV), a gas gap switch having a high energy trigger device, a turbo molecular pump, and two types of demountable FX tubes, each of a different type. The FX distribution was controlled to the wide energy latitude from very soft to slightly hard in order to perform the single exposure (flash) energy subtraction radiography. The peak intensity of the FX spectrum rapidly shifted the high photon energy region according to insertion of metal filters. Various single exposure subtraction images were obtained by the subtraction between the soft image (no filter) and the hard image (after filtering).

The construction of a serial (triple) exposure type of high intensity flash x-ray (FX) generator having variable energies for biomedical radiography is described. This generator consisted of the following components: two high voltage generators (positive and negative), a voltage divider unit, two types of high and low voltage pulsers with maximum output voltages ranging from 50 to 200kV, small-sized trigger devices, a trigger delay unit, a high power gas diode, one turbo molecular pump, and two evacuated remote FX tubes, each of a different type. In the case of using a single FX tube, the pulser were charged to the same or different energies from -100kV to +100kV by using a two voltage divider unit and were connected to the FX tube through a high power gas diode. On the other hand, when using multiple tubes, the pulsers were connected directly to the tubes without a diode. These FX's have many possible diagnostic applications as follows: (1) high intensity stroboscopic radiography; (2) double exposure subtraction and energy subtraction; (3) superposition of spectra; (4) radiation sources for the ultra high speed computed tomography and stereography; and (5) various kinds of imaging using pulsed electron beams and FX.

High speed photography with up to ten rotating turbine-mirror cameras is one of several diagnostics used at the Lawrence Livermore National Laboratory (LLNL) for studying the hydrodynamics of nonnuclear explosions. At each of the multiple camera test facilities, a versatile and extensive computerized fast camera control system supports operation of the cameras over a vast range of camera, rotor, and speed configurations. The camera controller functions are distributed over many components of the bunker control systems in which they are embedded, and represent a significant portion of the parent control system. The system facilitates preparation for experiments using speeds and configurations never before practical, greatly improves reliability, and maintains a database for rotor quality assurance.

This paper describes the implementation of a system for automatic light level control of an intensified solid-state television camera, by means of varying the gate pulse width of a gated second generation image intensifier, with pulse repetition synchronized to the television camera frame time (or to vertical sync).

Shuttering characteristics of low impedance stripline geometry microchannel plate image intensifier tubes (MCPTs) with 50% transmissive nickel undercoated S-20 photocathodes are discussed. Iris-free shutter sequences with 50 to 75 micron resolution at optical gate times of 500ps to 2ns were measured for typical samples from two manufacturers. Shutter sequences clearly showing gate pulse propagation velocities for this MCPT design when externally driven by impedance matched circuitry are contrasted with non-directional sequences obtained from unmatched coupling of the gate pulse.

A comparison of different manufacturers' microchannel plate image intensifier tubes (MCPTs) in coupled video systems is presented. Comparative performances in the areas of optical gating speed, resolution, gain, and phosphor efficiency are discussed. Relative sensitivities for various combinations of coupled MCPT/TV imager systems including P-20 and P-20R phosphors cascaded to FPS (focus projection and scan) electrostatic vidicons with silicon or Sb2S3 targets and CID (charge injection devices) solid state imagers are included.

There has been increased interest in streak images with large numbers of resolvable spatial points with good dynamic range. Tests have been performed on tubes from six different manufacturers in four countries (France, UK, USA and Japan). These include measurement of dynamic resolution, dynamic range, photocathode uniformity and absolute photocathode quantum efficiency. In general these tests were performed with sweep ranges from 10 to 100 ns in the visible portion of the spectrum. Results of these measurements comparing the different tubes will be presented. While dynamic range measurements were made by observing spot broadening as photocathode illumination was varied, the dynamic resolution was made at high light levels (a few times below saturation) only -- due to sensitivity limitations with our vidicon readout system. It should be noted that this tube characterization is an ongoing effort. The manufacturers are continually improving their products and our understanding of how to best characterize and compare them also undergoes a continual evolution.

The need to do high precision, time-resolved, optical and x-ray measurements at the Nova Laser System at the Lawrence Livermore National Laboratory has led to increased demands on the triggering requirements of the Target Diagnostics instruments. These diagnostics require a fast trigger that is synchronous with the target irradiation. Previously, oscilloscopes and streak cameras shared the same triggering system. The relatively short temporal window of the streak cameras and the need for pre-shot system monitoring and post-shot data analysis justified the development of an improved triggering system. This paper discusses a system dedicated to triggering streak cameras on the Nova system which provides 16 individually adjustable triggers that are synchronous with the incident laser beam to within 100 ps. This system includes the capability to monitor the sweep circuit of each camera to detect a difference in trigger timing with a resolution of 50 ps on both target shots and dry runs. Various other parts of the diagnostic/triggering system are also routinely monitored.

We are presenting test results which compare spatio-temporal resolution characteristics of three commercially manufactured soft x-ray streak cameras and a prototype of the C650X soft x-ray streak camera made at CEA Limeil-Valenton using an RTC P650X streak tube' and now commercially available from the Thomson CSF2 company.

An excellent photon counting streak camera (PCSC) which can detect single photoelectron with high temporal resolution has been developed. PCSC is adopting a photon counting streak tube (POST) which incorporates tandem micro-channel-plates (MCPs). Using this camera, single photoelectron images can be obtained with high gain and high S/N ratio. And Spatial resolution is measured to be about 11 1p/mm at supplying voltage 1800V to MCPs. Further, by detecting center of gravity for each photoelectron image, spatial resolution of 30 1p/mm has been achieved. Temporal resolution is evaluated to be better than 2 ps at single shot operation and 12 ps at synchroscan operation. Therefore PCSC will be useful for many fields, for example, time resoluved Raman scattering, the life time of fluorescence, photon statistics, and so on.

Some experiments investigating the limiting factors of the dynamic-range in a femtosecond streak tube have been carried out. In the experiment, the space charge effect at the crossover has been measured independently under the condition, where the number of photoelectrons getting at the crossover can be varied without changing that emitted from the photocathode. As a rusult, the space charge effect at the crossover is believed to be more serious than that in the photocathode and in the near field of the photocathode.

The characteristics of the uranium oxide cathodes for a neutron streak tube have been experimentally evaluated, using a conventional streak tube with 2 MCP wafers whose photocathode is changed into an uranium oxide cathode. It has been confirmed from the neutron image on the output phosphor screen that the detection efficiency (fission event/neutron) is roughly between 10-6 and 10-7 and each fission produces a few hundreds electrons emitted into vacuum. The temporal spread of--14ps has been obtained from the streak image of emitted electron cloud per one fission. On the other hand, it has been found from the experiment that in the practical use, the noise generated in the MCPs becomes an obstacle.

An excellent and simple multi-framing technique has been demonstrated as "femtosecond laser flashed frame imaging" utilizing a femtosecond laser and a femtosecond streak camera. A framing speed of approx. 2x10¹¹frames/s has been achieved at the first time by illuminating a transmission pattern with successive 100 femtosecond laser pulses with interval time of 5 ps. The ultrashort light pulses can be obtained from a colliding pulse mode-locked ring dye laser.

New two-dimensional sweeps of streak cameras; elliptical and high-dense sine-curve scans, have been demonstrated to be an excellent and useful method expanding its performance and application. These have been accomplished by applying a sinusoidal or ramp voltage to the second deflection (horizontal) plate of a synchroscan streak tube. The elliptical scan has enabled direct and time-resolved spectroscopic measurement of highly repetitive optical-pulses in the range of several gigaherts and long decay times in the order of one-half the sweep period. The high-dense sine-curve scan has allowed measurement of fluctuations of pulse-shapes and pulse-intervals in a highly repetitive pulse train, and jitter among driving signals of a mode-locker, pumping pulses and oscillating pulses of an actively mode-locked dye laser.

A frequency-chirped optical pulse provides a natural mapping between time and wavelength. We propose to utilize this correspondence to impress the time-dependence of transmissivity of a sample cell onto the spectrally-varying intensity of a frequency-chirped optical probe. The time-dependent transmissivity encoded this way would then be subsequently recovered from the time-integrated spectrum of the probe. Retaining one dimension of spatial resolution, the technique would produce an optical streak camera of potentially very high time resolution (better than 200 fs); other modifications would produce an optical framing camera having frame times less than 10 ps. Application is not limited to the optical regime: use with x rays is discussed, along with applications to different optical sample cells and detector cells.

An electrooptical time analyzer for frame and streak photography is designed for studying fast processes in a picosecond range. The device is controlled by linearly increasing voltages. It is possible to take three-frame sequences of pictures sized 6x6 mm. The new device allows the framing rate approx. 8 GHz with the frame duration of about 6 ps.

Designing high speed time analyzing image converter tube (ICT) requires the account of the dependence of its time resolution on the design of both its electron-optical system (EOS) and its deflecting system (DS). Presented below is the analytical way of estimating the ICT time response function (TRF) i.e. the response of the ICT to δ - pulse which, for the case of electrostatic and magnetic ICT's should take account of quadratic dependence of the electron travel time upon the longitudinal v and lateral u components of its initial velocity (the account of the later provides a correlation between the TRF of an ICT and the electron's escape point radius-vector r0). Furthermore, the effects of the DS boundary fields and its installation inaccuracy upon the ICT time resolution are analytically studied. The last section of the paper investigates DS operation under great scanning rates, analyzes the causes of image edge cutting on the ICT screen, and suggest ways to cure this trouble.

A pulsed laser photographic technique is being used to record ballistic impact phenomena occurring at high velocities (0.5-2.5 km/s). The primary tool in this effort is a new Cranz-Schardin camera system. An enclosed, solid propellant gun range having interchangeable 20-mm and 30-mm barrels is employed to launch both spherical and cylindrical projectiles at thin target plates. Use of the shadowgraphs to measure projectile orientation and velocity and to observe and quantify behind-target debris patterns is discussed. Camera triggering schemes are addressed as are the questions of resolution and accuracy in the computed projectile and debris velocities.

Probably the most severe obstacle in the widespread use of holographic interferometry has been the methodology for extracting the data from the hologram in a timely fashion. Holography makes possible the recording of more data than can normally be used because of this limitation. In recent years great strides have been made toward solving the problem of automated data reduction. Available co puter power, new codes, and detector arrays have played key roles. This paper reports the development and application of a low cost, automated interferogram analysis system including both hardware and software.

The technigue based on the anomalous dispersion phenomenon and used for measuring atom concentration in hypersonic wakes of ballistic models is described. Some details of the technigue are discussed related to the characteristic features of an experimental object and the method for analyzing interferograms being obtained. Possibilities of the technique considered are illustrated with the results of measuring distributions of Na and Cs atoms in the wakes (these atoms are supplied by ablation of the spherical model surface).

For high speed frame recording the use of well-developed tomography methods of cross-section image reconstruction of three-dimensional objects is suggested in this paper. In case of changing one of spatial coordinates z on a time coordinate t an analogue of series of cross-sections images, which are perpendicular to axis z, is a series of frames with various values of t. In this case projections needed for tomographic reconstruction can be realized as a set of streak records of two-dimensional images, obtained without a slit at various speeds of scanning. Analysis shows the possibilities of reconstruction the series of frames with temporal resolution approximating to that of streak recording.

Centered optical mirror systems combined of two spherical mirrors (modules) are described in.^1,2 This paper presents a more general definition of a mirror module incorporating decentered optical systems. A classification of mirror modules with a symmetry plane is given. A joint matrix description of meridianal and sagittal beams is suggested, and aberrations of plane meridianal beams of such modules are analyzed.

Large format framing in image converter cameras with a small exposure time (1 ns or less) is associated with significant difficulties in electronic circuitry design. The authors suggest an optical frame scan technique which may be used in combination with either a biplanar image converter tube with a large photocathode serving as a shutter, or a shutter-equipped ICT.

An aerodynamic holographic interferometry system has been developed and adapted for use with an existing supersonic wind tunnel. The tunnel had a 25.4 cm wide by 38.1 cm high test section, was an air-operated blow-down facility, and was run at nominal conditions of Mach number equal 2.85, total temperature of 270° K, and total pressure of 1.7 and 3.4 atmospheres. The associated fluid dynamics investigation centered on the SW/BLI problem occuring at an axisymmetric compression corner, physically created by a cylinder/cone intersection. The cylinder had a 5.08 cm diameter and was used with interchangeable conic flares of 12.5°, 20°, and 30° [each with cylinder afterbodies]. Complementary laser velocimeter measurements and Navier-Stokes computations are presented in support of the accuracy of the holographic interferometry results. The interferometry systems is illuminated by an available Q-switched ruby laser, which is expanded in the object beam to 30.48 cm diameter at the wind tunnel test section. A 5 mw He-Ne laser was used for alignment. The system features three modules: laser and reference beam, object beam expansion, and holocamera module. The design yielded excellent dynamic stability as a result of structural rigidity and placement of spatial filters far downbeam. Thermal stability also proved adequate. The system was easy to operate, and allowed for use with ambient lighting. Also, the system was necessarily operated remotely because of wind tunnel access limitations during a run. Cost figures and detailed equipment schematics are included in the paper. Additionally, the paper includes discussion of the Abel integral inversion program used to determine density profiles in the axisymmetric flow field from the recorded photographs.

Six airfoil interferograms were evaluated using a semi-automatic image processor system which digitizes, segments, and extracts the fringe coordinates along a polygonal line. The resulting fringe order function was converted into density and pressure distributions and a comparison was made with pressure transducer data at the same wind tunnel test conditions. Three airfoil shapes were used in the evaluation to test the capabilities of the image processor with a variety of flows. Symmetric, supercritical, and circulation control airfoil interferograms provided fringe patterns with shocks, separated flows, and high-pressure regions for evaluation. Regions along the polygon line with very clear fringe patterns yielded results within 1 % of transducer measurements, while poorer quality regions, particularly near the leading and trailing edges, yielded results that were not as good.

The possibility of using real time holographic interferometry (HI) to detect defects in printed circuit boards has been explored. Initial results indicate that real time HI can reveal some of the most common PC board defects such as solder crack, desoldered junctions, trace separation and components snipped at the soldered joints. In this study, thermal stressing was used as the probe since it did not require the board to be powered, and hence, allows the PCB test mounts to be simple. Our studies also indicate that holographic interferometry can detect and pinpoint more than one defect if present in the field of view.

The creation of surface relief holograms by thermoplastic deformation has proven to be an effective technique for many types of holography. Today, a major application is the field of interferometry. The technology of in situ development has vastly improved real time HI as applied to nondestructive testing and vibration analysis. In this paper, we describe the development of a dual plate holographic interferometer using thermoplastic recording devices. The operational characteristics of the thermoplastic devices are inves-tigated and optimized for fringe contrast and signal-to-noise ratio. The dual plate device is demonstrated in a transonic wind tunnel at NASA Ames Research Center. The interferograms derived from the thermoplastic device were compared with those derived from conventional photographic emulsions. The fringe contrast achieved with the optimized thermoplastic device was equivalent to the contrast achieved with conventional techniques. The operational advantages of in situ development was demonstrated in the wind tunnel environment, where the device was cycled from recorded hologram to reconstructed interferogram, in a few minutes.

The operation principles of the optico-electronic tomograph for the transparent object diagnostics is outlined. It is listed the processor algorithm, which enables to estimate the reconstruction accuracy and to take account of the influence of refraction.

A method of energy distribution recording over the laser radiation cross-section in an absorbing medium is considered.¹ The laser radiation under study is introduced into an absorbing medium where it changes the refractive index via its heating effect. The magnitude of the refractive index variation is correlated with the absorbing energy density as follows:²

The information contained in module λ(r) of the mutual coherence function was traditionally used to study the radiation sources proper. Some publications however have recently appeared ^1-3 showing promising ways to use this information for obtaining tomographic cross-sections of partially diffusing media and light cross-sections of 3-D diffusion reflecting objects.

Traditionally movie film has been the major medium by which investigators have analyzed, described and quantified the temporal and spatial characteristics of human motion. In addition, movie film has been used to estimate the forces resulting from the acceleration of the human body and its parts. Predictions of muscle force and reactive forces at the joints have also been made based upon film analysis. Although high speed filming was described as early as 1910, its use in the study of human motion was primarily from the 1960's onward. Filming at rates greater than 24 frames per second (fps) technically can be considered high speed. Most of the early human motion analysis was conducted using cameras operating at not greater than 128 fps, usually at 64 fps. These were relatively inexpensive cameras. The ultra-high speed cameras, however, were used to some extent during the early 1960's and became standard equipment in the well equipped University Biomechanics Laboratories for human motion analysis in the 1970's. As early as 1970 there were no fewer than four cameras capable of operating at speeds greater than 1000 fps. Cost, lack of comparable sophistication in analysis techniques, and operating complexities were primary factors in these ultra high speed cameras not being used to study human motion prior to the late 1970's. Human motion, even now, is usually recorded with cameras operating between 60 and 250 frames per second.

Motion Analysis Corporation is a manufacturer of videoâ€"based motion analysis equipment. The principal products of the Corporation are video processors and software to manipulate the raw data recovered by the video processors. Although these products represent the state-of-the-art in automated video-based tracking systems, relatively little is known about the performance of such systems. The present investigation establishes precise definitions for system accuracy, system precision, and "overall system performance". Both system precision and system accuracy depend heavily on the type of hardware used to produce and acquire the raw images; however, system precision is shown to be significantly better than system accuracy, and overall system performance appears to be similar to that rendered by traditional, film-based systems. Careful selection of image acquisition hardware, together with analytical corrections for systematic error can clearly improve overall system performance. Additional investigations are underway to determine the impact of alternative scaling techniques and analytical corrections for optical distortion. Preliminary results have show that affine scaling can improve system accuracy by 2-6X.

In order to produce better shoes that cushion athletes from the high impact forces of running and still provide stability to the foot it is essential to have a method of quickly and reliably evaluating the performance of prototype shoes. The analysis of rear-foot motion requires the use of film or video recordings of test subjects running on a treadmill. Specific points on the subject are tracked to give a measure of inversion or eversion of the heel. This paper describes the testing procedure and its application to running shoe design. A comparison of film and video systems is also discussed.

A variety of techniques for quantification and analysis of three dimensional movement has been described in the literature, but a number of practical problems limit their application. Such problems include: the requirement that moving objects be encumbered by wires attached to sensors or to active targets; undue constraint upon the number, location and orientation of imaging devices; inability to automatically track multiple targets; confounding the three dimensional trajectories of targets whose paths cross in two dimensional images; and lack of editing functions and adequate graphic feedback enabling the user to rapidly detect--and then easily correct--errors in tracking. The present paper describes software enchancements to the video-based ExpertVision system produced by Motion Analysis Corporation which provide for the analysis of movement in three dimensional space. The system can acquire time-matched digitized video data at frame-rates of 60, 200 or 2000 Hz using a variety of camera/VCR combinations. Software (and supporting hardware) has been developed to automatically calibrate multiple cameras and does not limit the investigator to utilize particular camera configurations. Additional software has been written to automatically track targets as they move through three dimensional space, to interactively edit three dimensional trajectories both during tracking and after the trajectories are computed, to display the data and to support three dimensional motion analysis.

This paper will give a brief overview of automated image-based motion tracking and motion analysis systems for use in different application areas. A motion analysis system consists of two major elements: (1) an image capture and image processing front-end coupled to (2) a signal processing back-end. Application areas can be categorized as systems that require 1-, 2- or 3-dimensional data capture and analysis. Each step along this dimensionality axis requires a quantum jump in sophistication and complexity.