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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.

An incoherent method for aberration measurement of micro cylindrical lenses is presented. For these lenses, it is difficult to measure the aberration by a coherent method with an interferometer. A method of retrieving the aberration from the intensity distribution of a light beam passing through the sample is proposed, and the accuracy and the spatial resolution of the measurement are discussed.

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.

When simulated annealing is applied to an ill-posed reconstruction of computer tomography images, the cost function should be appropriately modified to suppress artifacts arising from the ambiguity of null components. This paper shows such modification of the cost function and proves its performance through singular value decomposition analysis. Computer simulation shows good agreement with the analysis.

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.

This paper shows the possibility of finding the phase distribution of the wavefront and the mean phase difference between two interfering beams from the series of interferograms used in conventional phase shifting technique, without any additional measurement. A method for finding these phases is presented which can be applied under weak a nonlinearity of the phase shift.

An error analysis of wavelength scanning interferometry is shown, in which the interferogram obtained is constructed from more than one interferogram. Computer simulations are carried out to confirm the theoretical considerations in calculating the phase distribution of the individual interferograms.

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.

It is difficult to measure the optical surface shape of large area plane using interferometers. A part of the area of the sample is measured repeatedly by using a small aperture interferometer. The connection of the adjacent areas data is made with the aid of the least square method. This paper shows a method of connection of the measurement and shows some results of experiment.

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.

Change of wavelength in interferometry modifies interferograms without any mechanical movement. If a series of interferograms are taken by successive change of wavelength and analyzed by computer, it brings a new technique called wavelength scanning interferometry. Two examples of such a technique are presented.

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.

We propose a method to obtain the shape of a large plane surface by connecting phase distributions measured by a small-aperture interferometer. These separately measured phase distributions cannot be connected directly because the object will tilt or have vertical displacement during the measurements. To correct these errors, the measurements are made so that the adjacent interferograms have common areas, and these interferograms are connected to minimize the difference of the phase distributions in the common areas. A matrix equation is derived to obtain coefficients to correct tilt and vertical displacement, and the accuracy of connection increases in proportion to an exponent of 1.5 of the width of the common area.

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

We propose a high-speed surface reconstruction from three-dimensional data through optical–digital hybrid processing. Surface images are currently reconstructed through digital processing, which takes a long time mainly because of the rotation and interpolation of the volume data. In the proposed system, slice images of three-dimensional volume data are optically rotated and interpolated. In principle, one surface image can be obtained in the video rate when we use the same number of sets of optical processors as slices to be processed. Furthermore, this system could lead to a hybrid three-dimensional simulator; most operations such as rotation, cutting, digging holes, and peeling skins are interactively achieved at the video speed. Fundamental experiments are described that confirm the effectiveness of this method.

When halftone screened images are sampled by discrete array sensors such as CCD line sensor, moire fringes sometimes appear because of aliasing errors. We have proposed a “Dual Sampling Method (DSM)”, which can effectively suppress the moire fringes by carrying out twice sampling procedures with different sampling ratio. In this paper, we discuss the possibility of applying the DSM to color images. Two methods are described: the first one applied DSM to each primary color images, and the second one only to intensity data. A computer simulation shows the effectiveness of both methods.

Under the appropriate condition, it becomes possible that the excess optical path difference due to an off-axis scatter point cancels the optical path difference of an aspherical mirror from a spherical mirror. Using this condition, a new convenient method to realize the null test of aspherical mirrors is proposed without using any special optical element.

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.

The restoration of linear-motion blurring by the convolution method, realized by scanning a picture to be processed with an aperture of special form, is considered. Effects of the operation range of convolution and of the width of a segment in the aperture upon the restoration are discussed. The influence of noise in restoration processing with typical apertures is also discussed.

A simple and convenient technique for making a scatter-plate to be used as a component of a scatter-plate interferometer is proposed, and wide-angle and high-contrast interference patterns are obtained.

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.