The spherical aberration of the lens is concemed mostly with the index profile expressed by the distribution coefficients. The ray in the lens was traced by the third order approximate solution of the ray equation derived from the perturbation method and the aberration could beobtained theoretically. The aberration was measured precisely by a new method using laser beam and the distribution coefficients was determined so as to most fit the observed data by computer simulation.
An incident wave focused by a cylindrical lens onto a coupling prism base forms guided modes in a waveguide and gives a pattern of m-lines on a screen behind an exit prism. Using this phenomenon, it is found that an image information can be transmitted through the waveguide and a shadowgraph sampled by m-lines is given on the screen, if a transparency is inserted as an input pattern. In the same principle, the information of two-or three-dimensional colour image is also transmitted through the waveguide. The transmitting image information can be recorded as a planar imageguide hologram and reconstructed in the waveguide as guided modes.
A two-color diode laser printer has been developed. In the optics of this printer, two laser beams are scanned using single rotating polygonal mirror and FΘ lens on different places of photoconducter drum. The curve of scan line which arises in this case is corrected by a long cylindrical lens in front of an image plane. The system using a diode laser array is also evaluated.
We demonstrate a direct letterpress printing process which transpose the original letters to a photopolymer plate in the use of excimer laser beam. The photosensitized plastic resin plates are exposed to UV ray of 300-400nm. For the light source, the high pressure mercury vapour lamp which has a long exposure time was used. Xenon-fluorine excimer laser was used for the generation of very strong UV beam (350nm) to accept even low sensitive photopolymer plate. The critical hardening energy density was 40mJ/cm2 (10ns). The new method using this pulse beam for one letter is much simpler and easier than the laser scanning process requiring division of each letter into dots of 1 and 0.
Spatial summation properties were examined by the spatial double stimuli method, in which summation indices were obtained for various separations between two stimuli. Results were expressed by summation index curves where summation index was plotted as a function of separation. Summation index curves of three subjects showed diphasic nature having inhibitory interaction at separation of 5.2', but curves of four subjects showed only monophasic nature. Even when more proper optical correction was performed, they did not show any inhibition. It was suggested the receptive field properties were different among subjects.
A total simulation system which can simulate the color reproduction process of color photographic images precisely and can give “hard-copied” images to be evaluated visually has been developed. This system is able to be adopted to various applications on color images because of the following characteristics. (1) The spectral reflectance of the objects for each of the pixels in the scene can be measured. (2) The photographic color reproduction process can be totally simulated by a computer. (3) The results of the sirnulation are output as actual color images by a laser color printer.
A new method of testing optical flats of high reflectance is presented. The principles of this method are as follows'. 1. Accurate adjustment of the distance of a Fabry-Perot etalon is virtually realized by means of tilting the etalon. 2. Accurate phase detection is realized by means of utilizing the sharp fringes of multiplebeam interference. We measured the flatness of an etalon with simple setup and the Accuracy obtained is about λ/500.
A micro-computer controlled electro-optical system for automatic evaluation of displacement distribution from specklegrams in double-exposure speckle photography is developed. It is capable of random addressing of a laser beam on the specklegrams by using a pair of galvanomirror deflectors and electronic scanning of the resultant Young fringes by a linear photodiode array to determine their orientation and spacing. The fringes and oriented normal to the diode array by rotating a Dove prism until the computed value of the degree of modulation in the video signal becomes maximum, and then their spacing is evaluated. Examples of the automatic evaluation are shown as a vectorial diagram of in-plane displacement.
We have performed photoacoustic imaging of subsurface in a metal using a microphone detection method. A computer controlled photoacoustic imaging system is developed. A sample in a high sensitive photoacoustic cell is scanned mechanically and photoacoustic signals generated by focused laser beam irradiation are fed into a lock-in amplifier. The magnitude of photoacoustic signal is displayed on a graphic terminal of a micro-computer which controls the imaging system. Laser power dependence of the photoacoustic signal and some examples of subsurface imaging are presented.
Several experimental results on successive color discrimination are reviewed to investigate human memory for color. It is shown that the successive color discrimination threshold reaches to an asymptote of a certain discrimination threshold level with a relatively short temporal delay between presentations of two colors. This discrimination threshold level is shown to be almost constant even as the temporal delay increases further, and about twice greater than the simultaneous discrimination threshold in both wavelength and purity discriminations. Some important implications are discussed about temporal characteristics and degree of the color discrimination deterioration.
Hue substitution pulse, i. e. chromatic pulse without luminance change, mainly activates chromatic mechanism, and on the other hand, luminance pulse stimulates only achromatic mechanism. Two pulse technique combinating these pulse was applied to examine the dynamic interaction between chromatic and achromatic mechanisms. The perception probability showed an asynmetric behavior to ISI (interstimulus-interval). This results suggest that this method has some potentials to search this interaction, because the curve shows a synmetric figure when only one of mechanisms is activated. Furthermore, the maximum point and minimum point of the curves were exchanged when red light took the place of green light as a chromatic stimulus. These results were explained by a simple linear model of colour vision.
Two noncontact methods for measuring a surface profile of a steep aspheric surface, which are called Type 1 and Type 2, are presented. The scheme is based on a direct measurement of a slope of a surface by using a surface reflected laser beam. For the Type 1, a surface under test is moved by means of a rotary position table and a linear position table so that a returning laser beam is detected by a centering photodetector. For the Type 2, a laser beam is scanned by means of a galvanometer mirror instead of linear movement of a surface under test by means of a linear position table in the Type 1. A surface profile is determined by using a simple curve fitting technique for the measured data. Accuracy of the method is evaluated by an analysis of error caused by a misalignment of an optical setup. Usefulness of the proposed methods is shown throught experimental tests of a surface profile measurement of steep aspheric lenses.
Computer simulation program for projection lithography has been developed in order to study the performance of reduction projection aligner. The simulation procedure is as follows: First, the optical intensity distribution of the image on the photoresist surface is calculated for typical reticle patterns, thereby the influence of partially coherent illumination being taken into account. Next, the developed resist profile is simulated by the method based on Dill's theory. The program enabled us to know actual performances of the projection aligner; some examples of those simulations are shown in this report.
A novel optical head for digital audio disks has been successfully developed. The head consists of a GaAIAs laser diode, a quadrant PIN photodiode and a single-beam optical system for focusing and radial tracking. All of the data, focusing, and radial tracking signals are derived from a single quadrant PIN photodiode. Focusing and radial tracking servocontrol of the head are characterized by two-dimensional actuation of an objective lens and all the other optical components including the photodiode are kept fixed. However, it maintains superiod characteristics over a wide range of objective lens movement and disk tilt. The detection method of the error signals and their dependence upon both the objective lens movement and the disk tilt are described.
The MTF-50 is developed for measuring MTFs for production testing of camera lenses. For this instrument the reverse projection method with a magnification of 50 and digital Fourier transform procedure are adopted. Mechanical scanning and setting parts are reduced by utilizing CCD and numerical computation is mostly achieved by hardwares. The measurement by the MTF-50 is, therefore, quite fast and accurate. Although the MTF-50 has the high magnification of imaging, its compact design enables to be placed on production lines without any specific chamber. The MTF-50 is easy to operate for anyone. Its turn-around time for a measurement is about 15 seconds for 24 measuring points and the accracy is within 2 percent. Major points of development of the MTF-50 and its characteristics are described.
Gradient index lens posses promising optical systems so as to get very tiny spot as well as high coupling efficiency between light source like laser and optical fiber. The principle of focusing properties of gradient index lens and experimental results which have been obtained recently were described in the paper.
The holographic interferometer with an excellent controllability of a grating period is constructed for the application to the distributed-feedback and the distributed Bragg reflector lasers. The mirrors of the interferometer are set on the rotatable tables controlled by the personal computer. The deviation of the fabricated grating period from the expected one is less than about 0.05% in the range of the period of 2000Å. The grating structure is transferred to InP substrates through the grating relief pattern in photoresist by chemical etching. The relation of the diffraction efficiency to the grating depth is shown. Some characteristics of the fabricated 1.3μm GaInAsP/InP DFB lasers with SiO2 stripe are presented.
A new method to determine the central position of a rotating object is described. The principle is based on the fact that the tangential velocity of rotation becomes zero in the central position. Therefore, the velocity of several points along each Cartesian coordinate axis of the object is evaluated with a laser Doppler velocimetry. The central position is determined by straight line approximation in the method of least squares. From the experimental results, it is disclosed that by this method, the central position is determined with an accuracy of 1-2μm.
Waveform distortions of pulse and sinusoidally modulated lights used in optical distance measurement are calculated. They are caused by the dispersion of group velocity and limit resolution of the distance measurement.