Abstract: An optical low pass filter including a phase grating for obtaining useful picture image characteristics by provision of preferable low pass effects for each of wave form zones about the spatial frequency components beyond Nyquist limit which are required to be removed as the picture images are discretely sampled in nature in an optical system of a single tube color television camera having a color separating filter, a color video camera using solid state imaging elements, and so on, which is easier in construction to be constructed.

Abstract: A zoom lens includes sequentially from an object side toward an image surface side a fixed first lens group, a movable second lens group, a fixed third lens group, and a movable fourth lens group. The fixed first lens group is constituted by a first concave lens, a first convexo-convex lens, a second concave lens, a second convexo-convex lens and a meniscus convex lens. The movable second lens group is constituted by a meniscus concave lens, a concavo-concave lens and a convex lens. The fixed third lens group is constituted by a single lens having at least one aspherical surface. The movable fourth lens group is constituted by a concave lens and a convex lens, at least one of which has at least one aspherical surface.

Abstract: A wavelength-selective phase-grating optical low-pass filter has a phase difference structure formed at a boundary face between two layer materials which have different refractive index distributions and an identical refractive index at an intended wavelength. A trapezoid form is adopted at the phase difference section of the phase grating to achieve an excellent MTF characteristic in the condition of: ##EQU1## thereby obtaining a wavelength-selective phase-grating optical low-pass filter capable of adjusting the cutoff characteristic and improving the characteristic in the low-frequency region of the spatial frequency.

Abstract: A zoom lens comprises sequentially from a side of an object: a fixed first lens group constituted by a convex lens, a double convex lens and a meniscus convex lens; a movable second lens group constituted by a meniscus convex lens, a double concave lens and a convex lens; a fixed third lens group constituted by a single lens having at least one aspherical surface; and a movable fourth lens group constituted by a concave lens and two convex lenses at least one of which has at least one aspherical surface.

Abstract: A zoom lens of this invention comprises in successive order from the object side a first group having a positive refractive power and fixed, a second group having a negative refracting power for effecting a variation of image magnification by moving on the optical axis, a third group having a positive power for effecting a light condensing action and fixed, and a fourth group moving on the optical axis so as to keep an image surface position to be changed in response to a move of the second group and a move of the object in a constant positional relation with the reference surface. Comparatively large air space is provided between the third and fourth groups of the zoom lens.

Abstract: A zoom lens driving apparatus always detects a position of an image magnification varying lens section, and drives the image magnification varying lens section in accordance with a preset relationship between the position of the image magnification varying lens section and a zoom driving speed in such a manner that the driving speed becomes higher on one side, where the focal length of the zoom lens corresponding to the position of the image magnification varying lens section is small, than on another side where the focal length is large. Accordingly, the amount of focal shift, which in the zoom lens of the inner focusing system would otherwise abruptly increase with increasing focal length, is significantly suppressed, so that an auto focus adjusting mechanism or a focus correcting device effective during zooming, provided in the zoom lens, can function satisfactorily as to follow the focal shift of the zoom lens, whereby the lens control of a superior response can always be achieved.

Abstract: A video camera has an automatic focusing system provided with a focus detecting section for calculating and outputting a focus signal corresponding to a focus condition of an picked-up image from a video signal produced by an image pickup element. Either the image pickup element or a focusing lens in a photographic lens is oscillated back and forth of its present position, as needed, to detect an in-focus direction at the moment. The focusing lens is moved in the in-focus direction up to a position at which an optimum focus condition is obtained.

Abstract: A semiconductor light position detector for a rangefinder which projects a light beam onto an object and receives a reflected light beam from the object to measure a distance to the object. A portion of the light-receiving surface of the detector on which the reflected beam will not form a light spot is partially covered with a member that blocks unwanted light. Thus, the malfunctions caused by the flare component of the light from the light projector and the malfunctions due to increases in the shot noise under a high illuminance are reduced greatly.

Abstract: A projection lens for projecting an image appearing on a cathode-ray tube onto a screen, small in residual aberrations, having a high imaging performance, also having a large aperture ratio and a wide field angle, suitable for a video projector having a high definition of, say, 1,125 scanning lines. The projection lens has, successively from the screen side, a Gauss type lens system, a positive lens mainly for enlarging the aperture ratio, and a negative lens mainly for widening the field angle, which negative lens has a strongly concave surface at the screen end.

Abstract: A compact projection lens for projecting an enlargement of an image appearing on a cathode ray tube (CRT) onto the screen. The projection lens has a first lens having a positive optical power and at least one aspheric surface, surface of the first lens that faces the screen being convex, a second lens having bi-convex surfaces and a positive optical power, and a third lens having a negative optical power and an aspheric concave surface facing the second lens. The focal length f.sub.1 of the first lens and the focal length f.sub.2 of the second lens are selected for satisfying a condition of0.55<f.sub.1 /f.sub.2 <1.2.

Abstract: A surface acoustic wave transducer has a multilayered substrate which is made of a nonpiezoelectric plate which has a surface which is coated with a piezoelectric film, and has an interdigital electrode which is disposed on or under the surface of the piezoelectric film. The interdigital electrode has a split structure and the phase velocity of the surface acoustic wave of the piezoelectric film is smaller than that of the nonpiezoelectric plate.

Abstract: This invention provides a surface acoustic wave device which comprises a multi-layered substrate. The multi-layered substrate comprises at least a piezoelectric zinc oxide layer, an intermediate silicon oxide layer and an .alpha.-Al.sub.2 O.sub.3 base made of a single crystal havine an (0112) crystallographic plane or an equivalent crystallographic plane. This surface acoustic wave device is operable at ultra-high frequency.

Abstract: A surface acoustic wave device comprising a piezoelectric substrate which comprises an .alpha.-alumina layer as a base region and a zinc oxide layer as a surface region formed on the .alpha.-alumina layer. Preferably the two layers are each made of a single crystal, and the thickness of the zinc oxide layer and an angle between a crystallographic axis of the zinc oxide single crystal and the direction of wave propagation are determined so as to fall within optimum ranges, respectively. This device features an increased phase velocity and an augmented value for the electromechanical coupling coefficient and accordingly is of use at very-high to ultra-high frequencies.

Abstract: A surface acoustic wave resonator includes a base plate made of glass and a layer of piezoelectric material which has a plurality of strips extending parallel to each other for forming a reflector. A surface acoustic wave excited from a transducer reflects at each of the strips. The reflectance of such surface acoustic wave is improved by the arrangement of the strips and the thickness of the layer. On the other hand, the temperature coefficient of the resonance frequency is also improved by the arrangement of the strips and the thickness of the layer, and by the amount of the alkali metal oxide contained in the base plate, and further by the thickness of silicon oxide film laminated on the surface of the base plate.

Abstract: This invention provides a multi-layered substrate for a surface-acoustic-wave device which substrate comprises a piezoelectric layer on a base, the temperature coefficient of a phase velocity of the surface-acoustic-wave in the piezoelectric layer being different from that of the base, the piezoelectric layer having a thickness less than a wavelength of the SAW. This multi-layered substrate can have a large electromechanical coupling and controlled temperature coefficient of the phase velocity.