Abstract: A scanning image forming optical system disposed in a scanning optical system includes a single lens having the both surfaces thereof divided into a light-transmitting area and a light-reflecting area, whereby the scanning optical system is compact and various aberrations in the image forming optical system is improved.

Abstract: A scanning optical system with an improved scanning efficiency wherein a deflection space swept by a beam deflected by a deflecting surface of a deflecting device is divided into plural spatial zones, each of said divided spatial zones is provided with a transmission optical system for guiding the beam passing through each spatial zone to a scanned surface, and the beam scans said surface after passing through said transmission optical system is adapted to scan a same scan area whereby said same scan area is scanned plural times by the beam deflected by a single deflecting surface.

Abstract: This specification discloses a scanning device which is capable of providing a light spot moving at a uniform velocity on a surface to be scanned. The scanning device has a light source, an optical system for receiving the beam from the light source and direct a stationary beam to a deflector for collimating the stationary beam into a scanning parallel beam, and a scanning lens sytem for condensing the scanning parallel beam from the deflector onto the surface to be scanned. The deflector is a transparent polygonal member rotatable about a rotation axis at a constant speed and has a hollow portion whose cross-section orthogonal to the rotation axis is a circle centered at said rotation axis. The optical system causes the stationary beam to impinge at right angles from the rotation axis upon the cylindrical surface formed by the hollow portion.

Abstract: Two-dimensional scanning apparatus scans a stationary two-dimensional surface with a first deflector and a second deflector which deflects a light beam in a direction perpendicular to the deflecting direction of said first deflector. An afocal optical system is provided between said first and second deflectors, while an imaging lens system is provided between said second deflector and the scanning surface. Said first deflector, afocal optical system and imaging lens system cooperate to displace the light beam at a constant speed in a principal scanning direction on the scanning surface, while said second deflector and imaging lens system cooperate to displace the light beam at a constant speed in an auxiliary scanning direction on said surface.

Abstract: A light beam scanning device provided with a light source section to emit a scanning beam, a deflector to deflect the light beam from the light source section at a constant angular speed in a predetermined direction, and a lens system to focus the scanning beam deflected by the deflector on a scanning surface, wherein the lens system consists of two single lenses which are mutually positioned at a finite distance, the single lens at the side of the deflector has a negative refractive power, the single lens at the side of the scanning surface has a positive refractive power, and the scanning beam moves at a constant speed on the surface to be scanned due to the lens system having the f-.theta. characteristics.

Abstract: A lens which has a first positive lens group consisting of one or more positive lens or lenses, a second negative lens being a negative meniscus lens having its concave surface facing an object side, and a third positive lens having its convex surface facing an object side, being positioned in said order from an object side, and obtains high resolving power by satisfying:0.8 < R/Lwherein L is an air space on an axis between said second negative lens and said third positive lens and R is a radius of curvature of the surface of the third positive lens at the object side, and-0.18/F < 1/Rb < 0.18/Fwherein Rb is a radius of curvature of a surface of said third positive lens at an image plane side and F is a focal distance of the total lens system.

Abstract: This specification discloses a light beam scanning device in which a light spot is moved at a uniform velocity on a surface to be scanned. The light beam scanning device comprises a light source, a vibratory mirror and a focusing lens system. The vibratory mirror has its rotational angle (.phi.) vibrated at .phi..sub.o sin k.sub.1 t, and the light source is disposed at a location spaced apart by a distance r with respect to the center of the vibratory mirror. The focusing lens has a distortion characteristic expressed as: ##EQU1## WHERE Y' REPRESENTS THE IMAGE HEIGHT, L IS THE DISTANCE BETWEEN THE CENTER OF THE VIBRATORY MIRROR AND THE NODAL POINT OF THE FOCUSING LENS ON THE ENTRANCE SIDE THEREOF, F(.theta.) equals ##EQU2## WHERE F(.theta.) EQUALS .sqroot.R.sup.2 COS.sup.2 .theta. - L.sup.2 SIN.sup.2 .theta. - LSIN.sup.2 .theta., AND .theta. REPRESENTS THE ANGLE FORMED BETWEEN THE SCANNING BEAM DIRECTED TOWARD THE ENTRANCE SIDE NODAL POINT OF THE FOCUSING LENS AND THE OPTIC AXIS OF THE FOCUSING LENS.

Abstract: A variable magnification optical system comprising a stationary lens element and a movable lens element which when varying the focal length of the variable magnification optical system, are moved always in a relationship symmetric with respect to the center of the variable magnification optical system so as to effect a desired magnification.

Abstract: A catoptric projection system in which a projection lens and a spherical convex mirror are arranged with their optical axes intersecting at a point on the mirror at an angle with respect to each astigmatism so that an image is projected from the film plane with light after reflection from the mirror onto a light transmissive screen, thereby it being made possible to achieve a much-desired increase in the magnification of image projected on the screen without involving any increase in the magnification power of the projection lens or in the distance between the film plane and the screen. There is provided a cylindrical refracting surface disposed between the projection lens and the mirror to perform a refractive action in a plane containing both of their optical axes and to contribute an amount of astigmation which is balanced out by that of astigmatism introduced by the convex mirror.

Abstract: A varifocal lens system comprising a pair of movable lens groups located outwardly which are symmetrical with respect to the diaphragm and a pair of stationary lens groups located inwardly from said groups which are also symmetrical with respect to the diaphragm, said movable lens group being moved axially in the symmetrically spaced relationship with respect to the diaphragm and simultaneously the entire lens system being displaced as a unit by an axial distance depending on the amount of displacement of the movable lens group to satisfy the correct image-forming conditions throughout the entire magnification range while maintaining an object plane and an image plane spaced at a fixed axial distance.