Proceedings Volume 4768

Novel Optical Systems Design and Optimization V

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Proceedings Volume 4768

Novel Optical Systems Design and Optimization V

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Volume Details

Date Published: 4 September 2002
Contents: 5 Sessions, 20 Papers, 0 Presentations
Conference: International Symposium on Optical Science and Technology 2002
Volume Number: 4768

Table of Contents

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Table of Contents

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  • Optical Design
  • Illumination
  • Testing
  • Optical Data Storage and Theory
  • Poster Session
Optical Design
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Design and analysis of ultrafast systems using commercial optical design programs
Three commercial optical design programs are used to model familiar geometries in ultrafast optics. A set of macros has been created to calculate the pulse delay, group velocity dispersion (GVD), and third order dispersion (TOD) caused by components of an optical system. The programs have also been used to model a number of ultrafast pulse measurement systems using non-sequential ray tracing. This approach can provide evaluation, optimization, and insight into various pulse shaping schemes.
Design of a dual field-of-view imaging system for infrared focal plane arrays
In this paper, the design of a dual field-of-view optical system for 3-5 μm infra-red focal-plane arrays is described. Preliminary calculations are done to determine the first-order parameters of the narrow and the wide-field modes. To achieve a switchable dual field-of-view system, two different optical configurations, one based on the axial motion of a lens group and the other based on a rotate-in motion of two separated lens groups, are studied and compared. Diffractive and conic surfaces are used to control the color and the monochromatic aberrations with less number of total lenses used. Paraxial and real-ray modeling of the Narcissus effect is described. It is shown that the rotate- in scheme achieves better optical performance in both the narrow and the wide-field modes. The axial-motion scheme suffers from poor lateral color in the wide-angle mode. The final optical designs along with their aberrations curves and MTF plots are presented showing excellent performance.
Primary aberrations alleviated with phase pupil filters
Conventional optical system design enhances the resolution of incoherent imaging systems by optical-only manipulations or some type of post-processing of an image that has been already formed. This paper gives a brief introduction to a modern method, which employs an aspherical phase filter to alter the transmitted wavefront in such a way that the optical system has a high tolerance to aberrations. As reported in earlier work, this approach alleviates the defocus and its related aberrations whilst maintaining the diffraction-limited resolution for incoherent imaging systems. We propose to explore the control of primary aberration through the use of radially symmetric phase filters and this include spherical aberration, coma, astigmatism, and Petzval field curvature aberration. This method offers the potential to implement diffraction-limited imaging systems using simple and low-cost one- or two-element lenses.
Four families of flat-field three-mirror anastigmatic telescopes with only one mirror aspherized
In a recent paper the author described a method of acquiring the complete solution set of three-mirror anastigmatic telescopes with concave primary mirrors in which only one mirror is allowed to depart from being strictly spherical. There the solution sets were defined over a plane in constructional parameter space and four loci of points were identified representing solutions in which the Petzval curvature for the system was also zero. In the work presented below curves are fitted to these points. These curves represent the full range of possible flat-field three-mirror anastigmats with two spherical mirrors. Examples are given from each of the four families and algorithms are given in spreadsheet format which, for each of the four curves, will deliver a complete set of constructional parameters for a flat-field three-mirror anastigmat with two spherical mirrors for a given single input parameter.
Unobstructed afocal systems of spherical mirrors
Design methods are presented to facilitate studies of unobstructed afocal systems composed of two and three spherical mirrors. Only unobstructed systems with a plane of symmetry are considered. Low order imaging constraints are determined to eliminate available degrees of freedom and reduce the dimensionality of the configuration space. Example systems are presented.
Illumination
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Optics in large-scale architectural projects: public aquariums
Submersed aquatic vegetation can survive to a depth of approximately 20% of surface water irradiance. Large displays featured in public aquariums are often open to the sky, but the building roof acts as an aperture and obscures much of the direct solar path. Side-walls within the tank often absorb more than they reflect or scatter and as a result plants and fish get little more than the diffuse solar component without supplemental illumination. The loss mechanisms are detailed and design suggestions are considered, including heliostats, lightpipes and tracked parabolic reflectors with fiber optics.
First order property of illumination system
One of the well-known layouts of illumination systems for projection displays consists of an elliptical lamp reflector, an integrator and an optical relay. The presented analysis of the system is based on the paraxial properties of the relay and on the computer simulation of the source of light. This analysis allows system optimization, thus maximizing the geometrical collection efficiency for chosen lamp and for given etendue (target size and effective system F-number) of the optical system. Results of experimental tests are presented.
Lit appearance modeling of illumination systems
In illumination systems the look and feel are often more important than objective criterion, such as uniformity and efficiency. The reason for this is two fold: the lit appearance often sells an item and substantial variation in the illumination distribution (up to 50%) over a broad region is not noticeable to an observer. Therefore, subjective criterion, such as the lit appearance, typically plays a crucial role in the development of an illumination system. Additionally, by using computer models to ascertain the lit appearance before manufacture of the system, it allows the designer to modify the system while not demanding investment to produce prototypes. I discuss methods of determining the lit appearance for illumination systems. This modeling includes the inclusion of material and surface properties, such as surface finish, spectral transmission, and internal scattering; the response of the human eye; and the amount of rays that must be traced. By archiving the ray data, animations as a function of position and angle can be developed. Examples are developed to highlight the utility of this technique. These examples include taillights for the automotive industry and a backlit LCD screen for a laptop. Animations of these models demonstrate their luminance.
Method for high-power illumination of silicon for optically configurable microwave circuits
Photoexcited intrinsic silicon 'pixels' are applied as coupling elements between microstrip lines. Under proper illumination, the free-carrier concentration of the silicon increases sufficiently to pass a microwave signal across the pixels. Illumination is accomplished through the use of multimode fiber coupling between high-power laser diodes and multimode prismatic-waveguide output couplers. The prismatic couplers are fabricated on the endfaces of thick glass slab waveguides to direct the light onto the silicon pixel. This configuration delivers up to approximately 75% of the total laser diode light to the prism-waveguide couplers and these couplers, in turn, deliver up to approximately 70% of the input light to the silicon pixels. The prismatic waveguide couplers provide illumination uniformity within approximately ± 15% over the length of a 1mm X 5mm pixel. As a simple in-line coupler between microstrip lines, the fully illuminated pixel allowed an increase in transmitted signal of > 5dB over most of the range from 0.5GHz to 15GHz with > 10dB obtained over intermediate ranges. A silicon pixel tunable transmission line termination exhibits impedance matching at increasing wavelengths by successive illumination of multiple pixels, effectively increasing the length of the termination. This is illustrated by shifts in the resonant frequencies of the device reflection characteristics.
Integrating rod homogeneity as a function of cross-sectional shape
Chris F. Dimas, Steve Read, John J. Kuta
We present preliminary results from an analysis of irradiance patterns from integrating rods. A new metric is proposed to provide a more rigorous characterization of homogeneity as compared to the current ANSI standard for illumination and brightness of rectangular integrating rods used in the projector and display industry. This new metric is used in a computational ray-trace analysis to compare the relative homogenizing efficiency of integrating rods as a function of the polygon order of the cross section. Our analysis is performed for an ideal surface-emitting disk in order to yield general insight into the workings of integrating rods for common light sources, and a for full radiometric source model based on measurements of a reflectorized 100W Hg arc lamp. Simulation results indicate that a high degree of homogenization can be achieved for integrating rods with cross sections of polygon order equal to or less than 10. These results refute the commonly held belief that only integrating rods with tileable cross-sectional shapes are effective homogenizers. These results are particularly significant for optical applications in the materials processing industry.
Testing
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Design and analysis of a micro-optical speckle displacement sensor
The presented displacement sensor is based on the interference of a reference beam and the back-scattered speckle light from the moving surface under inspection. In contrast to incremental sensors this system works on nearly arbitrary surfaces without any special patterns. The design goal is a micro-optical system assembled with injection-molded plastic components and replicated gratings manufactured with lithographic technologies. The system design starts with ray tracing for the layout of the laserdiode module, the beam splitter grating and the refocusing optics. After this geometric optics first order design the profile of the buried reflection beam splitter grating is optimized with special diffractive optics design tools to achieve maximum efficiency in the required diffraction orders. The evaluation of the design is carried out mainly under two aspects: First part of analysis deals with investigation of aberrations and system tolerancing by ray tracing. The second part concentrates on wave-optical modeling of the changing interference signals, caused by the movement of the scattering surface.
Switched pattern laser projection for real-time depth extraction and visualization through endoscopes
Kurtis Keller, Jeremy D. Ackerman, Henry Fuchs
Gathering depth information through an endoscope or laparoscope during surgical or other procedures is quite difficult. There are stereo laparoscopes but generating three-dimensional models with them is very difficult. Accurate real-time generation of three-dimensional models through a laparoscope is a needed technology to enable a wide range of surgical applications. We have designed a miniature laparoscopic optical system consisting of a single laser whose pattern is modulated and uses the laparoscope as the optical display path into the body. Two cameras, one sensitive to the laser light and the other for full color imaging share this same tube as the laser projector but use the light from the opposite direction. The images gathered by the laser sensitive camera are used to generate a three dimensional map, and the color image is used to acquire the corresponding texture map. High-speed image processing hardware is used to generate 3D information using a structured light technique. The user can then re-render the acquired scene in 3D. The optical system is divided into a removable upper half consisting of the cameras, laser, digital light switches and combining optics. The lower half is the laparoscope or endocope that can be sterilized. There can be several variations in the configuration of the laparoscope optical half that tailor to different procedures.
Light source fluctuation effect on confocal imaging system
Anand Krishna Asundi, Chongxiang Li, Yanfeng Zhang, et al.
Confocal 3-D imaging technique is a newly developed technique and widely used in many fields of research and development. It is to utilize light intensity sensitive measuring technique. Confocal 3-D profile measurement system is widely used in high resolution inspection. For high precision 3-D imaging inspection in confocal measuring system, light source acts a very important role in system resolution and accuracy. In order to improve measuring repeatability and stability, to reduce measurement error, and to lower the light source stability requirement and cost, this paper studied light source fluctuation effect to confocal imaging measurement; deduced depth response model function; analyzed system error caused by light source fluctuation; and presented a new scheme to reduce the affection of light source fluctuation. Theoretical analysis and experiment result verified that light source fluctuation should be considered and eliminated in very high resolution confocal 3-D shape measurement system.
Double-detector-array 3D profile inspection system
3-D profile confocal optical microscopy is a newly developed 3-D profile metrology and has widely applied in many kinds of 3-D shape inspection fields. Present 3-D shape measurement system used in confocal optical microscopy is single point measurement. Point by point detection to finish a 3-D profile inspection is considered a time consuming method and isn't suitable for large area measurement especially for high resolution measurement. This paper elaborated on a fiber-array confocal 3-D imaging system to improve measuring speed. In confocal measurement system, light source acts an important effect on system accuracy and repeatability. Light source fluctuation can cause a large error for high resolution 3-D shape measurement. This paper presents a novel system construction to solve the problem of light source fluctuation. The system design is compact and the construction is reasonable.
Novel underwater 3D-target design for measurement of depth of gating (DOG) in underwater lidar imaging (UWLI)
Duo-Min He, Gerald G. L. Seet
When doing underwater lidar imaging (UWLI) in highly turbid water, its ICCD camera must be set in fast-gating status. As less than 50 ns, most gated-ICCD will become non-linear, which is difficult to be tested. In order to evaluate fast- gating performance in UWLI, we suggest a new technical term Depth of Gating (DOG) for depicting fast-gating feature of UWLI system, and design a novel underwater 3D-target for taking on DOG measurement. Our underwater 3D-target consists of a series of three bar test targets (five in total) at intervals of 22.5 cm roughly along, but separated on a section across, the laser illumination direction. The gap between two round trip times to two neighbor targets is 2ns for 22.5 cm interval, 4ns for (22.5 cm X 2) interval, etc. since the light speed in water is 22.5 cm/ns. From our experimental study, it is shown that using the underwater 3D-target designed in such a way is a practical and efficient method to measure short DOG value in UWLI system. We may simply name it 'underwater DOG-target.'
Optical Data Storage and Theory
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New quaternary material for high-speed phase-change optical recording
Geeta Mongia, Promod K. Bhatnagar
Over recent years the demand for mass storage devices with high speed has become increasingly more evident. Phase change optical recording is based on the rapid crystalline to amorphous (and vice versa) transition in a thin phase change layer enabled by laser induced heating. Among some of the potential candidates, AgInSbTe alloy appears to be one of the latest promising materials that has drawn world wide attention. The optical disk of this material with overwrites cyclability of more than 105 times, and data rate 22Mbps has been reported for DVD 4.7GB. Using this material as the active layer has other advantages such as the problem of material flow is reduced to a great extent. Moreover the marks written in AgInSbTe based media have a well defined shape with sharp edges, leading to intrinsically lower jitter values than observed for GeSbTe based media. In the present work [(AgSbTe)x(In1-y Sby)1-x] alloy and films are developed for different values of x and y. The crystallization process of Ag-In-Sb-Te films with above composition is systematically reported and compared for the first time. Thermal properties of the alloy and film are studied using X-Ray Diffraction (XRD) technique. The analysis of the film is done before annealing and also after 1hr. isothermal annealing at temperature between 200 degree(s)C and 500 degree(s)C. The structural analysis of the film is also done under same conditions (before and after annealing) using Scanning Electron Microscope (SEM) respectively. The experimental results of the analysis are presented here for compositions close to the eutectic Sb69Te31, in which some of the Te is replaced by Ag and In.
Some approaches to the analysis of properties of the prototypes of optical systems and choice of the starting point
Optical system databases give the lens designers an opportunity of search of the prototypes. However choice of the most acceptable prototype requires carrying out the analysis of optical systems on special techniques, which are absent in the majority of optical design programs. In this connection in this paper we present some approaches to the investigation of the limiting possibilities of optical systems and the aberration analysis on the basis of global expansion of the wave aberration into series in term of Zernike's orthogonal polynomials. The numerical examples of use of offered techniques are presented.
Poster Session
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Physical optics modeling of intracavity thermal distortions in solid state laser resonators
Laser resonators are very sensitive to intra-cavity losses and instabilities. When high power extraction is required, thermal distortions introduced from pumping the active medium cause the resonator to become unstable. We model these effects, and find a closed form solution to the wavefront change, as a function of time. Using physical optics modeling methods, we show that diffractive effects are needed to explain the onset of optical damage, and derive an analytical equation that describes the compensation of the resonator instabilities in real time for damage minimization.
Fast and effective algorithm for synthesizing computer-generated holograms
Enwen Dai, Changhe Zhou, Peng Xi, et al.
Over the past years great efforts have been made to find the optimization methods for synthesizing computer-generated holograms, e.g., kinoforms. The simulated annealing (SA) method is widely used in programing to approach the global optimization. But the drawback of the SA is it is time consuming. It is not possible to use the SA for some large computational optimization problems. So there is a strong need of the fast and effective algorithm. In this paper we propose a new optimization method, based on the modified Gerchberg-Saxton (G-S) algorithm, for synthesizing the large-scale kinoforms. Both phase and amplitude freedoms are used in this method. This method is especially suitable for the optimization of the large-scale kinoforms. It takes much less computational time than SA and the obtained image quality is also comparable to that of the SA. Another advantage of this method is that the reconstructed image quality is adjustable to meet the different requirements by controlling the noise parameter. The diffractive efficiency or the uniformity of the reconstructed image can be enhanced selectively to satisfy the different needs by the adjustment of the noise parameter. Using this method we have obtained several large-scale kinoforms with fast speed. The pattern of a binary kinoform is transferred into the glass plate by inductive coupled plasma (ICP) technology. Experimental results are also given in this paper to show the effectiveness of our methods.
Surface wave excitation control by using interface conductivity on one-dimensional photonic crystals
Khashayar Mehrany, Sina Khorasani, Bizhan Rashidian
In several recent papers, layered waveguide structures with conductive interfaces have been discussed, whose propagation properties are controlled by a transverse voltage. These structures have wide range of applications. In this paper, surface wave excitation on one-dimensional photonic crystals at the presence of interface conductivity is discussed. It is shown that excitation of electromagnetic surface waves can be controlled by the interface conductivity. This property can be used in constructing miscellaneous optical devices such as optical modulators, switches and tunable optical filters. Devices based on these waves can be superior to surface plasmon waves since they are not lossy. The lossless property is satisfied in limited range: millimeter waves to far infra red.