Shunsuke Yokozeki

Shearing Interferometer Using the Grating as the Beam Splitter

The theoretical interpretation of the shearing interferometer based on the moiré method using the fourier image of the grating is described. To obtain a pattern with good contrast, the observing plane must coincide with the normal fourier image plane of the grating or with the reversed fourier image plane. The information obtained by this method is the first partial derivative and under certain conditions the second partial derivative of the distortion from the reference wavefront, which is planar or spherical. Applications to measurement of the phase gradient and lens aberration are shown.

Collimation test by double grating shearing interferometer

The double grating shearing interferometry method for determination of the degree of light collimation is described. High accuracy is obtained by performing the observation of fringes in the area of the size twice as big as the one usually assumed in shearing interferometry experiments. The conditions under which such a detection mode is feasible are derived. They represent at the same time a very strong argument proving the highly diffractive (wave optics) character of the classical Ronchi test.

Collimation method using fourier imaging and moire techniques

Abstract Two techniques are proposed for beam collimation with the Talbot interferometer. One is called the mismatch method in which two gratings with slightly different periods are used. In the other method (called the grating shift method), one of two gratings of the same period is shifted in its plane in the direction perpendicular to the grating lines.

Geometric parameters of moiré fringes

The incoherent illumination moiré phenomenon between a periodic and a quasiperiodic structure is examined by the use of the spatial frequency analysis of the resultant transmittance. This approach has an advantage in that it completely explains all the fringe parameters without considering the averaging effect of the detecting system. We obtain the basic equation of the original moiré pattern due to the beat phenomenon exclusively, without any external factors like, for example, the influence of the observing system. From the basic equation, we derive the fringe profile equation representing the moiré fringe shape and the fringe equation expressing the spacing, the orientation, and the local displacement of the moiré fringes. The fringe profile equation is experimentally verified. The sensitivity enhancement by the fringe multiplication method is readily interpreted by the use of the derived fringe equation.

Moiré Profile Prediction by Using Fourier Series Formalism

One of the theories of moire pattern prediction uses the technique of partial sum extraction in the Fourier series expansion of the transmittance distribution which is obtained as the product of composite gratings transmittances. Based on this technique a simple method for the profile prediction of moire fringes produced by the interaction of two binary type gratings is developed. The theoretical model adopted easily clarifies the interdependence between the parameters of the interacting gratings and resulting specific fringe profiles. It also gives a simple and fast interpretation of the moire fringe shape encountered in a moire display using the fringe multiplication technique.

Spherical Aberration Measurement with Shearing Interferometer Using Fourier Imaging and Moiré Method

The experimental and quantitative study of the measurement of the lateral spherical aberration with the shearing interferometer using Fourier imaging and the moire method is given. When the aberration of a camera lens with small f/number(1.7) is measured with an optical arrangement employing the spherical wavefront as a reference at the observation plane, the distortion correction of the obtained fringes is necessary. However, the fringe pattern directly illustrating the lateral spherical aberration can be obtained by the proposed optical arrangement using the plane reference wavefront, without correcting the fringe distortion.

Shearing Interferometer Using the Grating as the Beam Splitter. Part 2

In the previous paper, a Ronchi-type shearing interferometer was proposed, and the theoretical interpretation of the interferomxad eter and several experimental results were given. In this method, the distance between the grating and the observing plane (z = zp) is chosen so that a fourier image of the grating is formed in the observing plane and the distortion of the fourier image given by a phase object is detected by the moiré method. The optical arxad rangement for this method is shown in Fig. 1. The purpose of

Image subtraction using fourier-imaging phenomenon

Fourier-imaging phenomenon is applied to grid coding image subtraction scheme. Double exposure and real time arrangements using complementary grating implementation techniques based on the grating self-imaging properties in coherent light are proposed. The simplicity, experimental ease and quality of the processed images prove the effectivness of the proposed technique.

Moiré fringe profile prediction method and its application to fringe sharpening

The fringe profile of the moiré pattern resulting from the interaction between a regular and a distorted binary grating is studied. The moiré fringe profile prediction method in a generalized form is deduced and summarized in a table illustrating the relationship between the profile parameters of superposed gratings and those of moiré fringes. The method is confirmed by computer simulation and experiment. The conditions for dark and bright fringe sharpening are obtained by using the derived prediction method.

Modified Double-Beam Interferometer Using the Moiré Method

It is described theoretically and experimentally that the degradation produced on a double-beam interferogram by the imperfection of the optical elemeits is eliminated by using the Moiré technique. In this method the information of the phase object is obtained as the Moiré pattern by superposing the interferograms with and without the object through the imperfect optical system.