Jumpei Tsujiuchi

Bio: Jumpei Tsujiuchi is an academic researcher from Tokyo Institute of Technology. The author has contributed to research in topics: Holography & Image processing. The author has an hindex of 18, co-authored 78 publications receiving 795 citations.

Multiplex Holograms And Their Applications In Medicine

Abstract: 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.

Compensation of motion blur in CCD color endoscope images

Abstract: 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.

Optical Image Deblurring Methods

Abstract: Greatly sharpened images may be extracted from photographs which have been blurred either by accident (motion, lack of focus, atmospheric turbulence, etc.) or deliberately, for instance when ‘coded’ in view of special image processing or synthesis applications. Four image-deblurring methods may be distinguished: 1. Coherent optical analogue processing, 2. Incoherent optical analogure processing (non-electronic) 3. Incoherent opto-electronic analogue processing and 4. Digital computer processing. Of these, the methods 1 and 3 are reviewed in some detail, and some previously unpublished experimental results are given for illustration. Particular emphasis is also given to the distinction between image-deblurring methods operating directly in the spatial (image) domain, very powerful but developed so far only in special cases (e.g. defocused and motion-blurred images), on the one hand, and, on the other the spatial-frequency filtering image-deblurring methods, also quite general, but still in an early state of perfection. Both methods may require considerable further work before widespread implementation

Fourier-transform method of fringe-pattern analysis for computer-based topography and interferometry

Abstract: A fast-Fourier-transform method of topography and interferometry is proposed. By computer processing of a noncontour type of fringe pattern, automatic discrimination is achieved between elevation and depression of the object or wave-front form, which has not been possible by the fringe-contour-generation techniques. The method has advantages over moire topography and conventional fringe-contour interferometry in both accuracy and sensitivity. Unlike fringe-scanning techniques, the method is easy to apply because it uses no moving components.

Digital wavefront measuring interferometer for testing optical surfaces and lenses

Abstract: A self-scanned 1024 element photodiode array and minicomputer are used to measure the phase (wavefront) in the interference pattern of an interferometer to lambda/100. The photodiode array samples intensities over a 32 x 32 matrix in the interference pattern as the length of the reference arm is varied piezoelectrically. Using these data the minicomputer synchronously detects the phase at each of the 1024 points by a Fourier series method and displays the wavefront in contour and perspective plot on a storage oscilloscope in less than 1 min (Bruning et al. Paper WE16, OSA Annual Meeting, Oct. 1972). The array of intensities is sampled and averaged many times in a random fashion so that the effects of air turbulence, vibrations, and thermal drifts are minimized. Very significant is the fact that wavefront errors in the interferometer are easily determined and may be automatically subtracted from current or subsequent wavefrots. Various programs supporting the measurement system include software for determining the aperture boundary, sum and difference of wavefronts, removal or insertion of tilt and focus errors, and routines for spatial manipulation of wavefronts. FFT programs transform wavefront data into point spread function and modulus and phase of the optical transfer function of lenses. Display programs plot these functions in contour and perspective. The system has been designed to optimize the collection of data to give higher than usual accuracy in measuring the individual elements and final performance of assembled diffraction limited optical systems, and furthermore, the short loop time of a few minutes makes the system an attractive alternative to constraints imposed by test glasses in the optical shop.

Coupled-mode theory for optical waveguides: an overview

Abstract: The coupled-mode theory (CMT) for optical waveguides is reviewed, with emphasis on the analysis of coupled optical waveguides. A brief account of the recent development of the CMT for coupled optical waveguides is given. Issues raised in the debates of the 1980’s on the merits and shortcomings of the conventional as well as the improved coupled-mode formulations are discussed. The conventional coupled-mode formulations are set up in a simple, intuitive way. The rigorous CMT is established on the basis of a linear superposition of the modes for individual waveguides. The cross-power terms appear logically as a result of modal nonorthogonality. The cross power is necessary for the self-consistency of the CMT for dissimilar waveguides. The nonorthogonal CMT, though more complicated, yields more-accurate results than the conventional orthogonal CMT for most practical applications. It also leads to the prediction of cross talk in directional couplers. The conventional orthogonal CMT is, however, reliably accurate for describing the power coupling between two weakly coupled, nearly identical waveguides. For dissimilar waveguides, a self-consistent orthogonal CMT can be derived by a redefinition of the coupling coefficients, and it predicts the coupling length and therefore the power exchange between the waveguides accurately if the two waveguides are far apart. Three typical coupler configurations—the uniform, the grating-assisted, and the tapered—are examined in detail. The accuracy, scope of validity, limitations, and extensions of the coupled-mode formulations are discussed in conjunction with each configuration. To verify the arguments in the discussions, comparisons with the exact analytical solutions and the rigorous numerical simulations are made.

On the diffraction theory of optical images

Abstract: The theory of image formation is formulated in terms of the coherence function in the object plane, the diffraction distribution function of the image-forming system and a function describing the structure of the object. There results a four-fold integral involving these functions, and the complex conjugate functions of the latter two. This integral is evaluated in terms of the Fourier transforms of the coherence function, the diffraction distribution function and its complex conjugate. In fact, these transforms are respectively the distribution of intensity in an 'effective source', and the complex transmission of the optical system-they are the data initially known and are generally of simple form. A generalized 'transmission factor' is found which reduces to the known results in the simple cases of perfect coherence and complete incoherence. The procedure may be varied in a manner more suited to non-periodic objects. The theory is applied to study inter alia the influence of the method of illumination on the images of simple periodic structures and of an isolated line.