Abstract: Disclosed is a multi-beam image forming system, which has a light emitting unit including a plurality of light sources emitting a plurality of beams, and a table carrying a photosensitive film on which an image is formed with the plurality of beams. A sensor is provided on the table, and light amount of each of the light sources is detected by moving the table and the light source relative to each other. Further, based on the detected light amount of each of the light sources, compensation values are determined. The compensation values are used when the light sources are driven so that the light amount on the photosensitive film accurately corresponds to an image data.

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 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.