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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 <1/50 wavelength for the surface shape, and 10(-5) of the refractive index for a 5-mm thick optical glass plate.

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 threedimensional 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 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.

An advanced coded imaging system is described, and some results of phantom experiments are presented. The advanced method uses a pair of coherent codes (+ 1 and -1 codes) and has many advantages compared with conventional ones. One of the greatest advantages is that there are no sidelobes in the focal plane and only a few in other planes. Therefore, when an object can be regarded as two-dimensional, it is perfectly reconstructed with high detecting efficiency, and this is successfully simulated by a thyroid phantom with 99mTc. Moreover, this system has an ability to reconstruct tomograms, which is also shown by using ring phantoms piled on one another with some cold spots in their shells. From these experimental results it may be concluded that the new system is useful for practical applications, for example, to nuclear medicine.

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.

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.

Color CCD endoscopes with sequential three-color illuminations have the advantage of high spatial resolution but are sensitive to object motion. A digital method is proposed for the restoration of images color-shifted by the object motion. The method makes use of phase-only matching followed by a resampling operation to compensate for a space-variant shift between different primary color images. Restored images are suitable for further image processing such as color emphasis and structure enhancement.

We propose finding an optimal generalized color plane to carry out digital color image correlation. We seek the optimization of the correlation peak's sharpness and, for the purpose of analysis, we make some assumptions regarding the statistical properties of images to be considered. The analysis leads to a simple solution involving a projection onto the Karhunen-Loeve vectors corresponding to the smallest eigenvalues of the interprimary colors covariance matrix. We use our results in the retrieval of the gastric mucosal surface structure from stereopairs taken through an endoscope. Study of the statistics of the endoscope images shows that the assumptions used earlier can be applied to this type of image. We present some results of stereopair matching with color image correlation. We conclude by proposing a pseudo-3-D surface reconstruction of the gastric surface by mapping the endoscopic image onto the retrieved elevation information.

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.