Recent advances in the Fourier spectroscopy are reviewed from the experimental point of view. New mathematical and experimental techniques, which have been developed after the basic principle and advantage of the Fourier spectroscopy were widely recognized, are briefly described. These include: 1) the methods of numerical calculation such as the special real-time computers, the apodization a posteriori, the interpolation and the related functions, the correction of asym-metric interferogram, and the improvement of resolution beyond the optical limit, and 2) the experimental techniques such as the application of the two-beam interferometer to the measure-ment of instrumental function, the use of the field-widener, the effects of solid-angle and finite optical path difference, the asymmetric interferometer, the relation between maximum path diffe-rence and S/N, the heterodyning and the new Connes' interferometer.
An attempt is made to obtain optimum values of weighting factors in automatic correction of lens aberations. Each weighting factor is a product of the following two factors. 1) “Intrinsic weight” τi, which is prescribed by the designer, determines the relative efficiency in correcting the i-th aberration. 2) “Compensating factor” σi, which is defined by σi=C (|grad gi|)-1, where C is a normalizing constant and gi the i-th aberration. Here, |grad gi| is regarded as a suitable measure for the difference in effectiveness of aberration correction. Results of numerical experiments suggest that, in most cases, all the intrinsic, weights can be set equal to unity and the assignment of weighting factors can be made to some extent in an automatic way.
The image by a gas lens of laminar flow type is experimentally analyzed with the optical transfer function. The variation of the line spread function of the gas lens is measured as a function of variables and parameters (temperature, wind velocity, distance) concerned with imaging cction of the gas lens. The focal length of the gas lens is also measured by the use of the line spread function. Further, the space frequency which gives the first zero point of the optical transfer functions is obtained from the line spread function and image of Simens-star, and discussion is made on the space frequency bandwidth of the gas lens.
In order to convert CIE colorimetric system to Munsell renotation system, a program for a digital electronic computer has been prepared. The modified chromatic-value system, which was proposed and is based on the Adams' system, is employed between CIE and Munsell systems to decrease certain systematic errors of this conversion procedure. The estimation of Munsell value is performed by using the Newton-Raphson's method, and that of Munsell hue and chroma is performed principally by using a vector algebra. Furthermore, Munsell renotation of each color chip of the JIS Color Standards (involve about 1000 color chips) is computed by this procedure and the computed results are compared with the results obtained graphically by the traditional procedure.
The intensity distribution curves in two-beam interference between two rectangular slits in a beam of quasi-monochromatic lightfrom an incoherent slit source are investigated in the out-of-focus fields. Examples and discussions are given to develop general principle which may apply to illustrate the fringe anomalies.
An apparatus was constructed for measuring the flare light caused by photographic lenses for an infinitely large object of uniform luminance. The object was the inner surface of a large sphere, painted mat white and illuminated uniformly, on various positions of which could be placed the dark opening of an artificial black body. The opening was imaged by the lens under test, and the illuminance of the image was measured photoelectrically. The ratio of the illuminance to that of the image of the inner wall is called the flare factor. The flare factor of a definite lens measured for black openings situated near the optical axis of the lens varies usually with the diaphragm of the lens, having larger values as the lens was stopped down. The phenomenon was -considered to be caused mainly by the flare light due to the multiple reflections of light at air-to-glass interfaces of the lens. The distribution of the flare factor on the image plane of a simple lens system was deduced theoretically, which showed good agreement with the experimental result for the system.