Abstract: An optical beam modulating device used for recording halftone plate duplicate images on a recording material including two multi-channel optical beam modulators, each including a rectangular parallelepiped modulator crystal which has a prescribed number of acoustic electrodes installed on one side surface. The electrodes are installed at equal pitch intervals so that Gauss beams can be directed across the electrodes separately from each other, and the positions at which the electrodes of one modulator are installed are shifted by one-half pitch with respect to the positions at which the acoustic electrodes of the other modulator are installed.

Abstract: A method for correcting the path of a gas laser beam by reflecting the beam with a first mirror, further reflecting such reflected beam with a second mirror, and then reflecting the beam reflected by the second mirror with a first half-mirror, passing such reflected beam through a condensing lens and then reflecting it with a second half-mirror. The beam passing through the first half-mirror is received by a first photodiode, and the beam passing through the second half-mirror is received by a second photodiode, and prior to the use of the gas laser, deviation of the beam passing through the first half-mirror is detected via the first photodiode to eliminate such beam deviation via actuators, and deviation of the beam passing through the second half-mirror is detected by the second photodiode to eliminate such beam deviation via another actuator, so that the path of the beam reflected by the second half-mirror is corrected to a given path.

Abstract: An optical beam splitter which splits a single light into a plurality of split beams including a plurality of transparent plates of uniform thickness arranged in a stack with fully reflective films coated on the transparent plates at both ends of the stack and semi-reflective films coated on the remaining transparent plates in the stack. The reflectivities of the individual semi-reflective films gradually increase from one end to the other in the stack and a beam entering the stack is first entirely reflected by the back-end fully reflective film, then passes through the semi-reflective films while being reflected partially by the semi-reflective films, and then finally entirely reflected by the front-end fully reflective film so that a single beam is split into a plurality of parallel split beams.

Abstract: An optical beam splitting method and optical beam splitting/modulating method for recording halftone plate images on a recording material through controlling a light exposing device by image signals obtained by photoelectric manipulation of an original image. Two light beam splitters are used so that a single light beam can be split into a plurality of split light beams which are lined up in two rows and shifted by one-half pitch with respect to each other and then modulated in multi-channel ultrasonic modulators, one row of the light beams being modulated with a delay without causing crosstalk. The number of split beams to be modulated is approximately doubled compared to a conventional system, and the size of the dots on the recording material can be decreased so that the image resolution is remarkably improved.

Abstract: An optical beam splitter including a prescribed number of stacked transparent parallel plates whose thicknesses are uniform to a high degree of precision, the back surface of the transparent parallel plate which is the farthest from the side at which light beam that is to be split enters is coated with a totally reflective film, while the back surfaces of all of the remaining transparent parallel plates are coated with different semi-reflective film whose respective reflectivities gradually increase and the coating region of the totally reflective film and semi-reflective films are positioned in an oblique arrangement which is struck by the light beam traveling obliquely through the interiors of the transparent parallel plates.