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In this paper, we propose a differential interferometry to measure the radius of a concave mirror. This technique needs two sequential measurements before and after shifting the sample perpendicular to the optical axis. The radius of the spherical mirror is calculated from the difference of the phase distributions of the interferograms, and so the reference wavefront does not influence the measurement.

In this paper we propose a new design of a joint transform correlator in which two transform lenses are used to minimize the influence of their aberration, and a magnification lens is used to make the optics compact. Experimental results show the correlator can be used to recognize characters and/or halL tone images in real time.

Three-dimensional reconstruction of a bone image is important in medicine to facilitate making artificial bones by numerical control and to achieve computer simulations of surgical operations. Instead of gathering sectional tomograms obtained by computer tomography, a direct 3-D reconstruction, which is much better in terms of higher spatial resolution and smaller X-ray dosage, is used to extract the bone's shape. A proposal and an experimental result are presented in this paper.

A radial shearing interferometer with two equispaced circular gratings is described for obtaining a constant radial displacement of the test wavefront. The procedure for the fringe analysis is shown by applying the Fourier transform method to the circular fringe pattern for precisely obtaining the differentiation of the test wavefront. A novel method is also shown for holographically making the equispaced circular gratings by using a cylindrical mirror and a collimating lens. It is shown that the deflection and misalignment of the gratings will not appear in the interferogram by using the holographic production method.

The characteristics of the surface relief hologram which is produced by a photoresist and its replica by an embossing method are experimentally studied. It becomes clear that the maximum diffraction efficiency of the photoresist hologram and that of the replica hologram are almost the same value—21–25%—and the maximum SNR of the original hologram and its replica are fairly good.

A practical method is shown to make wide view angle rainbow holograms. A cylindrical or a conical mirror is used to make the holograms and 150 degrees of the horizontal view angle can be obtained without difficulty. Tolerance of setting the optical system is discussed and an experimental result is shown.

A new technique to measure the radius of a concave mirror is proposed, in which the radius is calculated from the difference of the two interferograms obtained before and after shifting the sample perpendicular to or along the optical axis. By comparison of these two shifting directions, it is shown that since the amount of shift can be measured accurately and the result is insensitive to the tilt during the shifting, better accuracy can be obtained by shifting the sample along the optical axis.

An image processing technique to display a distortion-free reconstructed image from a rainbow type conical holographic stereogram is proposed. The method consists of forming a new set of 2D images from the original set by applying an image process. The image processing method is made through ray tracing equations. The results show that the performance of the proposed method is good as it removes distortion of the image.

The conical holographic stereogram is considered an interesting example for holographic display. To form a conical holographic stereogram, the 2D images are recorded on a series of slit holograms following a circle pattern. This procedure however, introduces some problems. It causes the reconstructed image be composed of an assembly of different image portions reconstructed from the slit holograms, and since the slit holograms are arranged in a conical structure, the reconstructed image is seen widened at the top and narrowed at the bottom. To cancel the distortion and correct the perspective view, an image processing is performed on the original set of images. By picking up pixel data of successive frames of the original set, a new set of 2D images is formed.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A new method to record a color holographic stereogram and its application in the synthesis of a conical holographic stereogram are presented. The method consists in recording three rainbow holograms on each slit hologram. To obtain the three images reconstructed on the same place, the position of the projection screen is changed when recording the three rainbow holograms. The difference of the projected image's size that appears because of the movement of the screen, is corrected by introducing a cylindrical lens in the projection system. Results of the method, feasibility and distortion of the image are discussed.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Usefulness of the Plate Optics with grooved base plates in constructing hologram recording equipments was reported in the previous paper. This paper reports an improved type of Plate Optics called Mole type Plate Optics, and proposes a simple computer-aided design for constructing optical systems on the Mole type Plate Optics.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Interferometers always measure the relative phase distribution of a sample to a reference subject, and absolute measurement of the sample is difficult unless the exact shape of the reference phase distribution is known. A method of differential interferometer, in which the differences of two interferograms obtained before and after the slight change of parameters in the optical configuration is measured, can be used to measure the shape of the sample without the exact knowledge of the reference phase distribution. This method is applied for measuring the radius of curvature of a Newton gauge.

An automatic hologram synthesizing system is developed for medical use. The purpose of this system is to synthesize cylindrical holographic stereograms of white light reconstruction for displaying various kinds of medical images such as X-ray, CT, MRI, etc.. To make the use of the system easy and processing rapid, a computer is employed to make the system automatic and to convert original medical images into images suited to hologram synthesis, compact size optical system is designed, and a liquid crystal spatial light modulator is employed as an interface between computer and hologram synthesizer.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Wavelength change in a unbalanced interferometer makes phase change in interferograms, and this phenomenon can be used for the purpose of phase shifting interferometry. As an example of measurements, an optical plane parallel plate is tested, and the simultaneous measurement of both front and rear surfaces together with inhomogeneity of refractive index can be carried out. A new method for calculating phase distribution is developed under the condition where nonlinearity of tuning wavelength and fluctuation of output power take place.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A method for displaying 3D images of medical objects by using holographic stereogram is described together with basic properties of reconstructed images of cylindrical holographic stereograms. INTRODUCTI ON A holographic stereogram (HS) is a synthesized hologram from an original film which consists of a series of ordinary photographs taken from different directions of an object and is possible to apply to an object whose hologram is very difficult or impossible to take with conventional techniques [U. Such a feature of HS can be used for 3D display of medical images such as X-ray images computer assisted tomogrphy (CT) images nuclear magnetic reasonance images (MRI) or ultrasonic images of a patient. CYLINDRICAL HOLOGRAPHI C STEREOGRAMS The original film of the medical HS is taken by rotating around the body axis of a patient a U-shaped arm equipment one end of which has a pulse X-ray source and the other end a movie camera with an image intensifier [2]. Synthesis of HS is carried out by using a special optical system the hologram is shaped into a cylinder and is reconstructed by illuminating the hologram with a small white light source located on the axis of the cylinder. Such a HS is called multiplex hologram (MH) the most popular HS and the reconstructed image can be observed in the cylinder. The formation of reconstructed image is made in unusual way and fundamental properties

If an iaage is reconstructed floating above the holorai plane it gives strong three dilensional lipression. A holograi having the shape of corn is suitable for this purpose and this paper presents the iethod for uaking conical holographic stereograis 1.

A proposal for an image distortion compensation and perspective correction method for a rainbow-type color conical holographic stereograms is presented. The image processing method is accomplished through ray-tracing equations. The approach taken consists in applying an image process to the original set of images to generate a new set of 2-D images. Using this method, the original object perspective is recovered and a full color image without distortion is displayed at the center of the conical holographic stereogram.

A new method to record a color holographic stereogram and its application in the synthesis of a conical holographic stereogram are presented. The method consists in recording three rainbow holograms on each slit hologram component of the holographic stereogram. To obtain the three images reconstructed on the same place, the position of the projection screen is changed when recording the three rainbow holograms. The difference of the projected image's size coming from the movement of the screen is corrected by introducing a cylindrical lens in the projection system. Results of the method, feasibility, and distortion of the image are discussed.

A phase shifting interferometer using a tunable laser as a light source is proposed for measuring shapes of both surfaces of a glass plate and the distribution of refractive index. To separate the superimposed interferograms generated with many wavefronts reflected from the plate, the phase shift associated with the wavelength shift is applied in the phase shifting interferometer with unequal optical paths in testing and reference beams. A laser diode is used for the tunable light source, and the data processing for obtaining phase distribution is based on the least-squares fitting in interferograms. The rms errors of the measurements are

Methods for making conical holographic stereograms are developed for monochromatic light and white light reconstructions, and real and virtual image reconstructions. One of the advantages of a conical holographic stereogram is the possibility to reconstruct real images with a simple parallel white light illumination.

On thermoplastic-photoconductor media, the holographic characteristics and the enhancement of sensitivity for light intensity have been studied and it is found that the diffraction efficiency depends strongly upon the intensity of laser light and that the sensitivity becomes higher as the thickness of single layer photoconductor increases. Double layer and a triple layer photoconductor systems which are more sensitive than a usual single layer have been developed. The most sensitive photoconductor system is a triple layer photoconductor system, that is PVK+CV*10:4 PVK:TNF complex+BG*10:4 PVK:TNF complex, the critical intensity is less than 1 erg/cm2.s and is about a tenth of that of a usual single layer. The main reason for the sensitivity enhancement of the triple layer photoconductor system is to absorb the charge carriers which are injected or cannot arrive at the transparent conductor. Another reason is to make a kind of inclination in the distribution of charge carriers created by an exposure to a laser light in order to make strong the Coulomb's force.

An imaging method for partially coherent objects is proposed by the aid of the propagation law of mutual intensity, and it can be reduced to principles used in holography and radio astronomy if the coherence reaches the both extremes, i.e., perfect coherence and complete incoherence, respectively.

An edge effect in thermoplastic-photoconductor media has been studied and it is found that the edge effect is in proportion to both the light intensity and the spatial frequency of the (holograms, and is more remarkable in the PLA method than the conventional simultaneous method. These results suggest that the edge effect is caused by the electric field which is bent by the uneven surface charges, the trapped charges and the localized charges in the photoconductor medium.

A thermoplastic photoconductor material is well-known as a hologram recording material. The dynamic ranges of a thermoplastic hologram are studied in two softening methods. One is the conventional heating method, and the other is the newly developed solvent vapor method. It is found that the solvent vapor method makes the dynamic range ten times as wide as the heating method, and in the solvent vapor method exposure time and charging voltage hardly affect the final diffraction efficiency.

This paper proposes a dynamic zone-plate interferometer (DZPI) which can measure quite accurately both shapes and surface errors of aspherical mirrors or lenses. By changing the wavelength of the illuminating light in fine steps, the DZPI gives a series of interferograms in which fringes are shifted almost continuously. Therefore, all their orders can be identified even when the maximum order becomes greater than 100. From these many interferograms, the shape and surface error of an optical instrument under test can be calculated with high precision by computer. A simple experiment confirms the validity of the DZPI.

If machines or apparatuses radiate partially coherent sound waves, locating their sources can be performed by the reconstruction of an acoustical hologram produced by the waves themselves. Since the practical spectrum of the sound fluctuates, a time average of the hologram signals can be taken, and a lock-in amplifier is used for the purpose. Using rotating gears as a test object, an experiment based on this principle has been successfully carried out to obtain the distribution of radiation sources at a frequency of 9·9 kHz.

A simple interferometric method is proposed for constructing equispaced circular gratings. This method uses only a cylindrical mirror and a collimating lens, and the radial spatial frequency of the gratings thus constructed is a function of the focal length of the collimating lens. A change of radial spatial frequency of the grating can be performed by changing the focal length of the collimator. A continuous change of the frequency can be obtained by using a zoom lens.

This study extends the analysis of image formation and aberrations in holography to that of high order diffracted waves to find a method for compensating the aberrations. The proposed method is able to eliminate all aberrations simultaneously by utilizing special conditions. Experimental results are also presented to support the method.

In the fringe-scanning methods such as the three- and four-bucket methods, the phase of a reference wave is generally changed at equal intervals from 0 to 2π. In practice, however, it is difficult or almost impossible for some interferometers, such as the dynamic zone plate interferometer, to realize an equal phase shift and to make a full scanning of 2π, which are necessary for discrete Fourier transform analysis. We show that even in such a case, phases in an interferogram can be obtained by using a Fourier analysis in a continuous space, and we analyze the accuracy of the phase determination in case of additive noise.

In recent years, remarkable progress has been made in high precision machining for the production of metallic concave mirrors. However, to improve efficiency and precision in the cutting process, it is desirable to design a measurement device built into the cutting machinery and to be easy to handle. In this paper we propose a promising and practical innovation in measurement based on zone-plate interferometry. This method involves the operation of changing the curvature radius of the diffracted wave fronts by moving the zone-plate along the optical axis, and it has the merit of easy application to the measurement both spherical and aspherical mirror profiles.

In the case that the image reconstructed from a cylindrical holographic stereogram with laser light reconstruction (LCHS) is observed by binocular vision, the 3-D distortion characteristics of the image are studied. Using an object of a distinctive construction, some examples are calculated and experimental results are also shown, and the optimum condition to synthesize the LCHS is given.

If a hologram of a vibrating object is recorded on a photographic plate which vibrates synchronously with the object, the reconstructed image produces equi-amplitude fringes of the object vibration, the amplitude of which is reduced by a constant determined from the amplitude of the plate vibration. This phenomenon can be used as a method to extend the measurable range of vibration amplitudes, and some experimental results are shown.

The authors have constructed a specially designed microscope interferometer which can observe the image of a point source or periodic pattern simultaneously with wave aberration, and made a series of experiments to make clear the correspondence between the aberration and the definition of image. Spot diagrams and response functions are also calculated numerically from the wave aberrations. The importance of the method of illumination was ascertained in these experiments by comparing perfectly coherent and incoherent illuminations. Les auteurs ont perfectionne un interferometre a microscope special permettant d'observer l'image d'lune source ponctuelle ou d'un objet periodique en meme temps que l'aberration d'onde; ils ont fait une serie d'experiences pour se rendre compte de la correspondance entre l'aberration et la definition des images. Les graphiques montrant les points d'intersection des rayons avec le plan image (the spot diagram en anglais), ainsi que les reponses en frequence spatiale, ont ete obt...

A combination of a holographic phase filter with a photographic amplitude filter for the use of coherent spatial filtering is studied for the purpose of the restoration of blurred photographic images.

In addition to conventional optical elements, mechanically flexible optical fibers of 17 μm in diameter are successfully used as coherent optical probes for vibration measurements based on optical heterodyne techniques. This means a feasibility of mechanically flexible setup for vibration measurements.

The third- and fifth-order wavelength-shift aberrations for an off-axis holographic zone plate for the higher orders are discussed, and numerical calculations of the aberrations are presented. A stigmatic point image can be obtained in the nth diffracted order if the wavelength-shift ratio is equal to 1/n.

Multiplrex Holograms are printed by using a liquid-crystal television receiver as a spatial light modulator instead of silver-halide movie film. Reconstructed 3-D images of wire-frame model can be observed with high contrast. But, some noise which is caused by LCTV is also observed.

The holographic stereogram is synthesized from a series of ordinary photographs, and is a very attractive medium for displaying 3D images. This paper presents a method of synthesizing a cylindrical hologrphic stereogram with white light reconstruction called multiplex hologram, and fundamental properties of reconstructed images such as distortion and resolution. An application to 3D display of medical X-ray images is proposed.

A method for automatically measuring the three-dimensional (3-D) deformations of a diffuse surface is studied, using a real-time holographic interferometer and a television-computer system. The object surface is illuminated from three different directions. The scattered waves are recorded on a thermoplastic hologram. Real-time holographic interference patterns are observed through the hologram in a fixed direction by sequentially applying the three illuminating beams. The three fringe patterns are put into the computer using a television (TV) camera. The relative fringe order numbers are determined over the whole surface. Calculations for obtaining 3-D deformation distributions are performed, and the results are displayed on a cathode-ray tube (CRT) monitor.

Fundamental properties of reconstructed images from a multiplex hologram are studied, and conditions for compensating distortions and for designing a reconstructing source are proposed. Applications of multiplex hologram to medical objects are reviewed, and a computer-aided hologram synthesizing system is proposed for obtaining better images and wider applications. An example of multiplex holograms synthesized from a series of CT images is also presented.

A cylindrical holographic stereogram with white light reconstruction, or a multiplex hologram can be conveniently used as a tool of non-destructive testing if the original picture is taken with X-rays. Along the lines of that purpose, it is discussed making holograms, optical properties of reconstructed images, mainly with regard to distortion and resolution, and a proposal of applying to medical purposes.© (1983) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Thermoplastic photoconductor materials are conveniently used for recording holograms because of their interesting advantages, but the processing is rather delicate and making good holograms is not easy. These difficulties are surmounted by developing new techniques for processing holograms such as the post-exposure light application (PLA) method and the the solvent vapour method, and applications of thermoplastic hologram have been still more promoted. This paper presents outlines of these new techniques together with some of their applications in the field of optical metrology and image processing.

Optical precise and rapid method for the inspection of shape error of gear tooth surfaces is developed. Laser light reflected specularly from the gear tooth surfaces is modified to converging spherical wavefront, which converges to a small point. The light intensity through the pinhole put at the position of the converging point is measured photo-electronically. The decrease of the electronic signal coresponds to the surface shape error of the gear tooth.