Abstract: An objective lens for an endoscope including a first lens group including one negative lens, a second lens group having a positive power, a third lens group having a negative power, and an aperture stop provided between the first lens group and the second lens group. The objective lens satisfies the relationships:-1.4<f.sub.1 /f<-0.5,0.55<f.sub.2 /f<0.85;andf.sub.3 /f<-2.0,Where f designates a focal length of the entire objective lens; f.sub.1 designates a focal length of the first lens group; f.sub.2 designates a focal length of the second lens group; and f.sub.3 designates a focal length of the third lens group.

Abstract: An objective lens for an endoscope includes a first lens group having one negative lens, a second lens group having at least one positive lens, and a third lens group including a positive lens. The objective lens satisfies the following relationship:.theta..sub.g,d <-2.223.times.10.sup.-3 .cndot..nu..sub.d +1.365wherein .theta..sub.g,d =(n.sub.g -n.sub.d)/(n.sub.F -n.sub.C), n.sub.g represents the refractive index of the glass material of the first lens group at the g-line, n.sub.d represents the refractive index of the glass material of the first lens group at the d-line, n.sub.F represents the refractive index of the glass material of the first lens group at the F-line, n.sub.C represents the refractive index of the glass material of the first lens group at the C-line, and .nu..sub.d represents the Abbe number of the glass material of the first lens group.

Abstract: For an aperture plate to be used to form dot images of a two dimensional aperture pattern by projection through an imaging optical system in a normal direction, a pattern of markings in ideal positions is projected through an imaging optical system in the reverse direction to normal imaging operations. The image of the pattern is recorded at the position of the aperture plate, and the recorded image is used as a guide to form corrected apertures in the aperture plate. Accordingly, locational errors of the dot images in the normal direction are corrected when the corrected aperture plate is used.

Abstract: A projector has projecting optical systems. The projecting optical systems have image formers and projecting lenses for projecting the images onto a screen. The optical axes of the projecting lenses are intersected with each other on the side of the screen. The image formers are arranged such that an image surface of each image former is coincident with the screen in accordance with Scheimpflug's rule.

Abstract: A chromatic aberration correcting element that is a simple lens having at least one aspheric surface the radius of curvature of which increases from the optical axis toward the periphery, at least either one of the surfaces being formed as a diffraction lens surface that consists of annular segments in steps that are shifted discretely in a direction in which the lens thickness increases as a function of the distance from the optical axis. Also, a chromatic aberration correcting device having annular segments formed in steps on either a light entrance face or a light exit face or both, the annular segments being composed of planes perpendicular to and concentric with the optical axis.

Abstract: An objective lens for an endoscope includes a first lens group of a positive power having a plurality of lenses, and a second lens group of a negative power. The first lens group is provided with a negative first lens located adjacent to an object to be photographed. The objective lens meets the requirements defined by (1) 0.6<f.sub.F /f<1.0, (2)-6.0<f.sub.s /f<-1.0, and (3) 1.0<L.sub.D /f<4.0, where f.sub.F designates a focal length of the first lens group, f.sub.s designates a focal length of the second lens group, f designates a focal length of the whole lens system, and L.sub.D designates a sum of the whole lens length and back focal distance.

Abstract: An objective lens for an endoscope includes a first lens group having one negative lens, a second positive lens group having at least one positive lens, and a third positive lens group having a cemented lens consisting of one positive lens and a negative lens adhered thereto. The objective lens satisfies the requirements defined by the following relationships:.theta..sub.g,d <-2.223.times.10.sup.-3 .multidot..nu..sub.d +1.365; and,-1.2<f.sub.1 /f<-0.8,wherein .theta..sub.g,d =(n.sub.g -n.sub.d)/(n.sub.F -n.sub.C), n.sub.g represents the refractive index of the glass material of the first lens at the g-line, n.sub.d represents the refractive index of the glass material of the first lens at the d-line, n.sub.F represents the refractive index of the glass material of the first lens at the F-line, n.sub.C represents the refractive index of the glass material of the first lens at the C-line, .nu..sub.d represents the Abbe number of the glass material of the first lens, f.sub.

Abstract: A projector has projecting optical systems which include image formers and projecting lenses for projecting the formed images onto a screen. The optical axes of the projecting lenses are intersected with each other on or very near the surface of the screen. The image formers are arranged such that an image surface of each image former is coincident with the screen in accordance with Scheimpflug's rule.

Abstract: An exposure apparatus where a mask table having an exposing pattern and a work to be exposed are relative to each other movable, wherein the moving amount of the mask table is detected by a scale image formed through a projection lens system, so that even if the projection lens system has a magnification error, by optically offsetting it, the moving amount of the mask table can be detected. Thus, a more accurate control can be obtained so that a mask image can be more precisely reproduced on a work.

Abstract: A scanning pattern drawing apparatus which scans the surface of a workpiece with a light beam so that a pattern is described on the workpiece with the issued light beam being controlled on the basis of pattern drawing data stored in a pattern memory, wherein the pattern drawing apparatus is able to read many pieces of data in a short period of time even if the frequency of the timing pulses is reduced and which therefore is capable of drawing a precise pattern on a workpiece. A scanning pulse generator produces as scanning pulse in response to a predetermined amount of scanning with the light beam. The scanning pulse is converted to a plurality of resulting timing pulses, and successive parallel outputs of the timing pulses are produced after delaying by a predetermined time. The pattern drawing data is read from the pattern memory in response to the delayed timing pulses.

Abstract: A drawing surface adjusting mechanism suitable for use with a large scanning pattern drawing apparatus in which a scanning optical system scans drawing rays of light along scanning lines on a workpiece on a drawing board. A plurality of light-emitting units project rays of light in a wavelength region outside a sensitivity range of the workpiece onto a drawing surface of the workpiece in such a way that the rays substantially converge at more than one point along a scanning line of the drawing rays of light, preferably at center and end points along the scanning line. A plurality of condenser lenses are provided for focusing beams of light from the plural light-emitting units after the beams have been reflected by the drawing surface. A plurality of light-detecting elements are disposed at points of condensation by respective ones of the condenser lenses to produce output signals representing differences in condensation points that occur as the lenses depart from or approach the drawing surface.

Abstract: An apparatus for correcting a scranning beam produced by a polygonal mirror tilting in small surface segments in each mirror surface segment caused by uneven mirror surfaces of the polygonal mirror. Data indicative of the amount of tilting in each of the surface segments is stored in a memory, which is addressed by a data signal indicative of the present scanning position of the polygonal mirror. Output data from the memory is applied to an acousto-optical modulator disposed in the beam path between the light source and the polygonal mirror.

Abstract: A monitor mechanism for use with a scanning optical apparatus in which the direction of polarization is utilized to separate a source laser light beam into a pattern drawing and a monitor beamlet and to synthesize them again into a single after passing through a scanning lens and beam deflector. The two beamlets can thus be controlled so as to project towards the deflector and scanning lens in the same direction, which is effective in reducing the offset between the pattern drawing and monitor beams that may occur on account of such factors as variations in lens performance.

Abstract: A drawing surface adjusting mechanism for use with a scanning pattern drawing apparatus capable of not only moving a drawing board in a vertical direction but also tilting it, whereby the chance of bringing the drawing surface within the depth of focus of a scanning lens is increased even if the drawing surface has waviness or other flaws within the width of a single storke of scanning.

Abstract: A table assembly that is simple in construction and which yet resists yawing in an effective way and is adapted for use with a scanning pattern drawing apparatus which involves continuous movements of the table. The inventive table assembly includes a master table that is slidable in one direction with respect to a fixed portion of the overall assembly and to which a drive force for causing the table to slide in the one direction is transmitted directly, and a working table that is slidable in the one direction with respect to the fixed portion and which is linked to the master table by connecting means having rigidity in the one direction and elasticity in a direction perpendicular to the one direction.

Abstract: A wide-angle zoom lens system comprises, in order from the object side, a first lens group having a negative refractive power, a lens unit having a positive refractive power and a second lens group having a positive refractive power. The system performs zooming by displacing the two lens groups and one lens unit independently in the direction parallel to the optical axis while maintaining the position of the image surface constant. The system satisfies the following conditions:D.sub.IW >D.sub.IT, and D.sub.IIW >D.sub.IITwhere D.sub.I represents the aerial space between the first lens group and the lens unit, and D.sub.II designates the aerial space between the lens unit and the second lens group, with the subscripts W and T representing aerial spaces for the short and long focal length sides, respectively.

Abstract: A focusing method in an optical lens system with a variable focal length is composed, in order from an object, of a first lens group having a negative refractive power, and a second lens group having a positive refractive power, with an air gap therebetween being variable for varying the refractive power. The second lens groups is divided into at least two lens groups. At least one of the last-mentioned lens groups is movable simultaneously for focusing and has a magnification which will not be -1 while varying power and focusing.

Abstract: There is disclosed herein several embodiments of a six-element telephoto lens system comprising, in order from an object, a first positive lens, a second negative lens, third and fourth positive-meniscus lenses having convex surfaces directed toward the object, a fifth negative lens, and a sixth positive lens, said lens system being arranged to meet the following conditions(1) 0.4f<f.sub.1, 2, 3, <0.75f(2) 0.35f<f.sub.1, 2, 3, 4, <0.6f(3) 0.65f<f.sub.1 <0.8f(4) d.sub.2 <0.02f(5) 0.2f<.vertline.f.sub.5, 6 .vertline.<0.45f, f.sub.5, 6 <0(6) 0.05<n5-n6wheref is the focal length of the overall lens system,f.sub.1, 2, 3 is the combined focal length of the first through third lenses,f.sub.1, 2, 3, 4, is the combined focal length of the first through fourth lenses,f.sub.1 is the focal length of the first lens,d.sub.2 is the distance between the first and second lenses,f.sub.5, 6, is the combined focal length of the fifth and sixth lenses,n.sub.

Abstract: A rear stop diaphragm type zoom lens is disclosed. The zoom lens is composed, in order from the object side, of a first lens group as a whole having a negative refractive power and consisting of two negative lenses and a positive lens and a second lens group as a whole having a positive refractive power and consisting of two or three positive lenses, a negative lens and one or two lenses including at least one positive lens. An aerial space between the lens groups is varied to thereby vary the magnification, and a stop diaphragm is disposed behind the overall lens system with the stop diaphragm being maintained at a constant position with respect to the focusing surface during variation of magnification.

Abstract: A focus detecting device having two concave mirrors for reforming the image of an object which is formed between a lens and the focal plane of lens, and for dividing said image two same secondary images. Two light receiving element arrays are provided in the image forming planes of the secondary images. A signal processing circuit subjects the outputs of the light receiving element arrays to produce a signal indicating whether or not the lens is focussed on the object. By means of the two concave mirrors adapted to form said secondary images, the two secondary images are shifted in the opposite directions on the light receiving element arrays at the time of defocussing so that the difference between the outputs of the two light receiving element arrays is not zero. At the time of proper focus the two secondary images are located at equivalent positions on said light receiving element arrays so that the difference between the outputs of the two light receiving element arrays is zero.