This PDF file contains the editorial “Rudolf Kingslake Medal and Prize” for OE Vol. 36 Issue 08

A novel method for performing color image pattern recognition using a fractional correlator (FC) is proposed. The input plane is illuminated with three different coherent sources of wavelengths corresponding to RGB (red, green, and blue) colors. The output plane provides a single output peak, which is a result of an incoherent addition between the three correlations obtained per each color. By using the fractional correlator, which is a partially space variant correlator, we achieve space-variance-controlled color pattern recognition. The use of the three-color illumination can drastically increase the discrimination ability of the suggested correlator.

The fast Hartley transform (FHT) algorithm for solving wellconditioned circular deconvolution is suggested. The arithmetic operations save about half compared to the fast Fourier transform (FFT) deconvolution algorithm. The Moore-Penrose generalized inverse of the circulant matrix connection to FHT matrices is investigated, then the least-squares solution for circular deconvolution is developed. An efficient numerical stable circular deconvolution algorithm is suggested by using FHT and truncated singular value decomposition (TSVD) techniques. An open problem is partially solved.

The concept of a new bidimensional photon-counting, MCPbased detector is presented together with estimates of imaging and dynamic range performances. The first results of tests on the position readout system, a silicon drift chamber, are also presented.

A theoretical analysis of the Fresnel field observed behind one or two binary amplitude gratings with different transmission parameters illuminated by a beam that is in part spatially and temporally coherent is presented. A mathematical model of the moire´-fringe-based optoelectronic transducer is developed. Suggestions for the design of a transducer with reduced manufacturing tolerances are presented and experimentally corroborated.

The optical part of a virtual reality system often contains an exit pupil that is larger than the entrance pupil of the eye. However, a system with a small exit pupil could have several advantages: a larger angular image field, more efficient use of light, less accommodation/ convergence conflict, and better optical quality. We examine two possible drawbacks of using a small exit pupil. One is related to the loss in image quality at exit pupil decentration and the other is related to the limitations in the freedom of eye movement. It appears that an optical system with a small exit pupil (?1 mm) and a large image field (>15 deg) is feasible only if a combination of eye-tracker and exit pupil shifting mechanism is implemented.

The optimal design of tightly jacketed double-coated optical fibers to minimize the mechanical strip force is investigated. The stripper is assumed to consist of two hinged arms and paired blades with semicircular bore. It is found that the strip force is a function of the bore radius of the stripper. The optimal bore radius of the stripper is equal to the radius of the primary coating. Based on the type of strip force, the stripping process can be divided into three steps. In the first stripping step, a strip force Ft is required to extend the crack on the cutting plane to the glass fiber surface. In the second stripping process, a strip force Fb is required to break all of the adhesive bonds at the interface of the glass fiber and primary coating. In the third step, a strip force Ff is required to push the polymeric coating tube off the glass fiber. For commercial tightly jacketed double-coated optical fibers, Fb is much larger than Ft and Ff . The strip force Fb could be minimized by a suitable selection of polymeric coatings and their thicknesses.

Typically a polyimide coating thickness of 12 to 15?m is applied to different optical fibers mainly for various high-temperature applications. Because this coating is so thin, handleability is an issue from the point of view of mechanical damage. To protect the polyimide coating from handling-related damage, a composite coating of polyimide and acrylate is typically applied to the optical fiber. We expose such coated fiber to deionized liquid water at 85°C and to steam for durations of 100 d in water and 26 d in steam. When the strength of the fiber is measured after aging in water, there is a slight drop in strength; but, surprisingly, there is no change in strength after aging the composite-coated fibers in steam.

A holographic optical element is developed that functions as a circle-to-point converter. The holographic plate looks like a zone plate but functions like a collection of field lenses. Each annulus of the holographic plate acts as a separate lens, imaging incident light to a point focus. The plate was developed for use with Fabry-Pe´ rot interferometers, but other applications are also possible. The plate has high throughput, and when coupled with high quantum efficiency solid state detectors provides an efficient photon-collecting detection system. Development of the plate was driven by need for an efficient Doppler lidar detection system, and specific lidar applications are discussed.

Texture- and shape-preserving, velocity-selective moving object estimation in time-sequential imageries are investigated. A 3-D spatiotemporal filter is usually effective for velocity-selective processing of nonmaneuvering moving objects. However, its performance is limited by the inherent aliasing problem due to discrete space and time sampling of continuous signals of moving objects with various motion vectors. To complement the imaging effects due to spectral aliasing apparent in the spectral domain processing, the time-recursive temporal low-pass filter, which is based on the Kalman theory, is incorporated in parallel to the proposed 3-D spatiotemporal filter banks. This temporal low-pass filter is effective in adaptively separating relatively stationary backgrounds from all other moving objects. In other words, the false moving objects due to the imaging effect can be successfully suppressed using the binary masks of all moving objects that are obtained through the simple type of time-recursive temporal low-pass filtering. From the simulation using several real IR image sequences, not only for the multiple moving objects with various shapes and speeds but also for the noisy image sequences, the highly accurate texture- and shape-preserving, velocityselective moving object estimation results are observed with a graceful degradation in accordance to the increased amount of noise

The quality of the image is crucial for the performance of a visual surface inspection system. The final image quality is affected by the properties of the imaging unit. In order to evaluate the quality of the imaging unit a designer should be able to characterize the imaging performance using quantitative figures of merit. The suitability of the modulation transfer function (MTF) for the figure of merit of imaging in visual web inspection is discussed. A straightforward setup for the determination of the system MTF is suggested. Three exemplary cases are analyzed: (1) the performance of an imaging system as a function of the system f number, (2) the performance of an imaging system against the depth-of-field requirement, and (3) the performance of a TDI imager against speed mismatching. In order to relate the system MTFs to image quality, a set of defective samples from a paper manufacturing process was collected and imaged. Quantitative image quality criteria are proposed, and the sample images are analyzed according to these criteria. The final image quality is compared with the corresponding system MTF values.

An efficient image compression technique using block grouping is presented. The similar blocks in an image are merged into a group in a recursive manner. The center of a group is then encoded with the Joint Photographic Experts Group (JPEG)-like algorithm. Simulation results indicate that the proposed algorithm improves the compression efficiency significantly, compared with the JPEG-like algorithm.

A new variable block size segmentation for image compression is proposed. The decision whether or not the given image block is homogeneous is based on a model-fitting criterion. More specifically, calculating the maximum log-likelihoods for all predetermined block patterns with respect to the given image data, we apply a modified Akaike information criteria (AIC) to select a best match. Then we can classify a given image block into one of texture, monotone, and various edges according to the characteristics of the selected pattern. Having classified nonoverlapping small square blocks, we can cluster homogeneous blocks to have a variable block size segmentation. Since the gray-level distribution in the block (i.e., the maximum log-likelihood) is considered in the model-fitting criterion, the proposed algorithm can differentiate edges from textures. Moreover, edge blocks can be further classified as having vertical, horizontal, or diagonal edges. Also, since the contextual information among neighboring blocks is considered to eliminate isolated blocks and to connect broken edges, we can have larger homogeneous blocks to guarantee a more efficient coding.

A non-destructive method used to estimate internal surface roughness of a small hole (0.2 mm in diameter and 0.7 mm in depth) is described. The first step of this method is to reconstruct a shadow pattern image of the internal surface from a series of optically sectioned images of the surface. The surface roughness parameters are then calculated from this shadow pattern image. The method is verified by measuring a known flat surface and comparing the results with stylus measurements.

When a Ronchi grating is stored as modulation of birefringence, it can be replicated (Talbot effect) if read out with coherent light. This is obtained by writing an incoherently projected grating in a photorefractive BSO crystal. Then, it is read out by collimated polarized laser light, which is outside of the crystal spectral sensitivity range. The ellipticity of the readout light exiting the crystal is determined according to the local birefringence. By rotating an analyzer the contrast of the free propagation replicated grating is controlled. Experimental results are presented.

The recent use of single mode fibers in electronic speckle pattern interferometry (ESPI) shows that it is possible to produce a small and compact system for the use even in a hostile environment. Standard single mode fibers are easy to handle but cannot preserve the polarization state of the input light when ambient conditions change during long term measurements. The quality of the ESPI fringes decreases and the performance of the measuring system suffers. Under this point of view the correlation of speckle patterns produced by light of different polarization states is investigated.

A new version of interferometer construction for absolute distance measurement is presented. It is based on measuring the contrast of a two-wavelength interference pattern with using a CO2 laser generating a pair of optical wavelengths simultaneously.

A real-time, full-field, noncontacting infrared Twyman-Green interferometer for performing deformation measurements has been developed. The choice of the wavelength offers the advantage of using the interferometer with structural components with little or no surface preparation. The limitation on the surface roughness/texture commonly encountered when using visible light is circumvented through a favorable roughness-to-wavelength ratio. Planar objects with a surface roughness up to ?a?1 ?m (or surfaces prepared using fixed abrasives with mean grit sizes up to 250?m) have been examined. Capability of the interferometer for quantifying deformations when dealing with rough surface measurements is demonstrated. Examples of defect detection as well as elastoplastic crack-tip-field mapping are provided.

We recently presented a novel approach using highsensitivity grating interferometry to measure in- and out-of-plane displacements. The interference of each of the specimen grating diffraction orders with the reference beam was recorded separately but not simultaneously. Computer subtraction and addition of the phase maps obtained from the interferograms yielded the in-plane and out-of-plane displacements (u and w). This article presents our continuing work with this interferometric setup, extending the application of this method to include the simultaneous registration of interferograms for analyzing time dependent events. The spatial separation of interferograms, accomplished by means of polarization techniques, allows for the simultaneous registration of interference patterns. The methods, employing two different sets of linear polarizations for the diffraction orders and two different polarizing beamsplitting elements, are described, and the experimental results are presented. Further modifications for sequential and simultaneous monitoring of all three displacements u, v , and w are suggested.

A new architecture of an optical neural network that uses a prism-array interconnection is proposed. It has advantages such as ease of fabricating, compactness in size, and better image quality. A detailed case study is given with the derivation of design parameters for a system with 1024 neurons. Finally, we provide a simple experimental demonstration.

Luminaires with diffuse reflectors can offer an efficient and inexpensive alternative to their specular reflector counterparts when good angular control of light and flux uniformity are secondary considerations. Via numerical simulation based on radiative transfer theory, we generate the brightness of all elements along the reflectors and the bulb, from which the luminaire radiance distribution and radiative efficiency can be calculated. Analyses are restricted to common commercial configurations: linear (2-D) V-trough geometries with purely diffuse reflectors, with realistic absorptivity values for bulb and reflector. There is excellent agreement between theoretical predictions and experimental measurements.

Some defects of common ray-tracing procedures for highorder aspheric surface are noted and a new reference sphere applied to ray tracing is presented. Its curvature is variable, which is different from the common osculating sphere introduced in the current literature. Concerning the iteration approach precision, a basic numeric criterion with a floating quantity attached and the corresponding program control are discussed.

The first-order solution is analyzed with particularly initial conditions for a two-conjugate zoom system that consists of three lenses. We find the solution ranges of system parameters with the conditions in which the object/image and pupil magnifications of the middle lens are taken to be 1 and -1 or -1 and 1, and the system magnification is 1 or -1 at the mean position of zooming. Several examples are given to demonstrate this analysis.

Procedures for creating high-resolution polarization filter arrays using multilayer polyvinyl alcohol (PVA) films are described. Two state polarization filter arrays with 25 ?m resolution and three state polarization filter arrays with 48 ?m resolution are demonstrated.

Many optical fiber sensors, designed to recover quasistatic strain fields in the presence of significant temperature changes, have been reported in recent years. A number of recent publications have attempted to devise a method for assessing the relative performances of such sensing schemes. Here we report an analysis that represents the data recovery process from a geometrical standpoint and provides useful insight into the physical differences between measurement schemes. The performance of methods based on Bragg grating sensors, polarization-maintaining Fabry-Perot interferometers, combined dualmode interference-polarimetry sensors, and dispersive Fourier-transform spectroscopy measurements are contrasted.

Comparative displacement measurements are made using laser diode (LD) and light emitting diode sources, fiber optic collimators, and a dual-photodiode detector (DPD). It is shown that a relative displacement resolution < 2 nm is possible with the LD source. This result is interpreted to indicate that the coherent LD sources illuminating the DPD temporally correlates the mutual irradiation function of the signals between each photodiode segment and significantly reduce electronic (shot) noise, reduces the variance, and thereby enhances resolution.

The possibility of using quadrant detectors to develop a new optical system that can monitor all six degrees of freedom of mechanical workpieces with very high resolution is investigated. A prototype system based on this approach has been designed and built. Although the system is not fully optimized, our proposed system has already demonstrated some promising results. Using a thermally compensated laser source together with a pinhole spatial filtering system, we have demonstrated that lateral resolution better than 50 nm and angular displacement resolution better than 0.25 ?rad is achievable with this system.

The switching mechanisms of ferroelectric liquid crystal optically addressed spatial light modulators (OASLMs) using a photosensitive structure made of an intrinsic amorphous silicon layer sandwiched in between an indium tin oxide coated glass sheet and a reflective metal layer are reviewed. Devices based on photoconductor and photodiode layers are briefly reviewed and attention is focused on pixelated metal mirror (PMM) devices, which offer fast switching and good optical characteristics with the same sensitivity range as the photodiode OASLMs. They are particularly suitable for high frame rate SLMs with intense read beams. Optimum drive conditions for this type of device are considered. An equivalent electrical circuit is proposed for the photosensitive structure and the voltage drop across the liquid crystal layer is investigated and related to the optical response of the device. Experimental work is carried out to demonstrate the validity of our equivalent circuit. We show that the synchronization of a light source with the case pulse enables the OASLM to work at frame rates of a few kilohertz. We also demonstrate that the exact synchronization of the write light source with the write pulse enhances the potential memory of the device.

A stereoscopic electronic speckle photography system is presented that detects 3-D displacement fields or object shape with subpixel accuracy. The system is all electronic, and data are stored, results are presented, and calculations are performed in a PC computer. The expected standard deviation of measurements of small deformations are about 0.001% of the object size for in-plane measurements and about 0.006% of the object size for the out-of-plane component, when white light speckles are used.

The coronal diagnostic spectrometer (CDS) is one of 12 instruments that form the payload of the joint European Space Agency (ESA)/National Aeronautics and Space Agency (NASA) Solar and Heliospheric Observatory (SOHO), launched in 1995. The CDS was designed and constructed by an international consortium led by the Rutherford Appleton Laboratory, United Kingdom. It is a high resolution, extreme UV telescope and spectrometer for making observations of the high temperature outer regions of the sun. The optical system is described and the theoretical performance of the design is discussed.

A multireference fringe-pattern projection (MRFP) method is developed for rapid measurement of the shape of an object that has spatially isolated surfaces. The method combines the commonly used fringe-pattern projection method and an acousto-optic deflector (AOD) scanner in one optical system. The AOD scanner generates reference fringes, whose positions can be conveniently adjusted to suit the respective object by changing the control signal to the AOD. We determined the accuracy of this MRFP method by measuring the displacement of a plastic plate and comparing the results with those obtained using a linear gauge. We find the relative accuracy to be 0.3%. To demonstrate the capability of this method to measure objects that have isolated surfaces, we use it to measure a vertical translation stage. Finally, we use it to measure the variations in position and shape of a fish while it is swimming. Such variation measurements are useful for studying the fluid dynamics of a swimming fish.

A technique for measuring the contour of a specimen’s surface is developed. A small microdevice produced by a micromachining technique and the electron beam scan of a scanning electron microscope (SEM) are used for this method. A small microgrid consisting of microsquare bars is placed over the specimen’s surface and obstructs the back-scattered electrons. Therefore, the shadows of the microbars are observed in the SEM image. The distance between the microgrid and the specimen’s surface can be calculated using the width of the shadow. This method makes it possible to detect the form of the specimen’s surface. As a demonstration, the shape of the Rockwell hardness tester’s indent mark is measured and the accuracy of this method is discussed.

Interferometry has been used widely to evaluate the largescale deviations from flatness of optical surfaces. However, when making measurements of small-scale irregularities with very small amplitudes, over a wide range of spatial frequencies, errors can arise due to scattered light and the transfer function of the imaging system. A theoretical analysis of these errors showing how they can be minimized is presented.

The structural, optical, and electrical properties of indium tin oxide (ITO) films coated on soda lime glasses with and without a barrier layer of TiO2-SiO2 composite films before and after annealing in air at 300 and 500 °C for 1 h have been systematically investigated using a x-ray diffractometer (XRD), spectrophotometer, and four-point probe, respectively. A TiO2-SiO2 barrier layer and an ITO layer were sequentially deposited onto unheated glass substrates by reactive ion-assisted electron-beam evaporation (IAD) using an advanced plasma source. Correlations between these properties and annealing temperatures and barrier-layer compositions are discussed. The suppression effect of a barrier layer on the outdiffusion of Na atoms from the soda lime glass substrate through the barrier layer into the ITO layer is investigated with secondary-ion mass spectrometry (SIMS). With respect to the optical and electrical requirements of ITO electrodes used in liquid crystal display (LCD) panels, ITO-coated soda lime glasses with a barrier layer of TiO2-SiO2 composite films with TiO2<50 at. % are superior to those with a barrier layer of SiO2.

A dynamic simulator of reticle seekers is developed to predict tracking performance in various engagement scenarios. We can analyze the performance of the infrared (IR) reticle seekers with targets in various positions in the field of view and with several SNRs. We show that the presented simulator is a very powerful means for developing signal processing algorithms in the presence of IR countermeasures (IRCM). A simple and efficient algorithm for IR counter-countermeasures (IRCCM) is proposed and simulated. With the incorporation of this IRCCM technique into the reticle seeker in the presence of IRCM, the missile can intercept its target successfully.

An image segmentation algorithm for segmentation-based video sequence coding is presented. The method uses a new criterion based on similarities in both motion and brightness. Brightness and motion information are incorporated in a single segmentation procedure. The actual segmentation is accomplished using a region-growing technique based on the watershed algorithm. It comprises the processes of extracting the initial regions called seeds and their growing by merging similar neighboring pixels. In addition, a tracking technique is used in subsequent frames to achieve a coherent segmentation through time. Simulation results show that the proposed method is effective in determining object boundaries not easily found using the static criterion alone.

Gamma thermometers have been in routine use in nuclear power plants for power distribution monitoring for more than 35 years. These instruments depend upon the heating of a metal block by gamma rays. The generated heat is proportional to the specific power of nearby fuel rods. Usually heat is allowed to escape to a sink through a controlled heat path and the temperature drop is measured by thermocouples. If the heat sink is at a known temperature, a single thermocouple may be employed to measure the temperature of the metal block.

This PDF contains the communications section that includes "Phase alignment of segmented mirrors using a digital wavefront interferometer"

This PDF contains the communications section which includes "Suppression of the dc term in digital holography"

This PDF contains the Communications and Errata for Optical Engineering Volume 36, Issue 8.

This PDF file contains the errata for “OE Vol. 36 Issue 08 Paper 601432” for OE Vol. 36 Issue 08

The literature abounds with texts on the subject of lasers. Any one book could provide a beginning graduate student with the tools necessary to understand lasers and their interaction with matter. However, the treatment of ultrashort lasers in such books is cursory, if included at all, since the intricacies of femtosecond pulse generation go beyond what is commonly considered fundamental.

This PDF file contains the editorial “Optical Diagnostics for Thin Film Processing” for OE Vol. 36 Issue 08