Abstract: A method for obtaining a desired picture with high quality by scanning a rotating recording drum by a scanning light beam, which produces images on the drum through a projection lens, receiving the said images being reflected from the drum through the projection lens on an image sensor, detecting variations of diameter of the drum per each rotation from variations of intensity of light of the images, whereby position of the projection lens being movable along the normal direction of the drum is automatically adjusted against machining errors of the drum diameter and variations of the said diameter caused by changes of its surrounding or any other reasons, temperature, so that variations of imaging points of the scanning light beam can always be within a range of depth of a focus of the projection lens.

Abstract: A method for automatically correcting variations in intensity of laser beams output from a projection lens, which variations occur due to variations of a spectrum pattern of optical fibers when their tip portions move, by paying attention to each of focal points of an image sensor which focal points correspond respectively to the optical fibers, comparing the sum of signal outputs from regions of the image sensor, which regions correspond respectively to the laser beams, with a signal output corresponding to a standard beam intensity required for the exposure of a photosensitive material to determine a value to be corrected, and then feeding the value back to acousto-optic light modulators so as to change the modulation efficienties of the acousto-optic light modulators.

Abstract: In a picture scanning and recording system such as a color scanner wherein a reproduction picture is recorded by modulating a plurality of light beams each independently according to a picture signal by means of light modulator elements, a method and apparatus for recording a reproduction picture having a substantially continuous tone characterized by weighting each light beam in order of digit position of a digitized picture signal, and effecting exposure with a light beam resulting from optical addition of the light beams modulated according to such a digital picture signal.