Color video projecting apparatus using acousto-optical deflector

DETAILED DESCRIPTION It is therefore an object of the present invention to provide a laser beam scanning system that is capable of producing a color image on a real-time basis.
It is another object of the present invention to provide a laser beam scanning system that is capable of producing a color image free from color dispersion.
According to the present invention, a laser beam scanning system comprises a laser source for producing a plurality of laser beams each having a different wavelength; a video signal source for producing color video signals the colors of which correspond to the respective wavelengths of the laser beams; a plurality of intensity modulators each receptive of one of the laser beams and one of the color video signals for intensity-modulating the corresponding laser beam with the video signal; a deflector for deflecting the intensity-modulated laser beams at an angle of scanning deflection which is dependent on the wavelength of the laser beam resulting in color dispersion of the deflector, the deflector being adapted to scan the medium in a given direction and produce the color image thereon; and a signal processor for adjusting the intensity modulation in such a manner that each of the laser beams is intensity-modulated differently in terms of scanning time from others to obtain substantially the same angle of deflection for all the color beams.
According to the preferred embodiment, the intensity modulation video signal for a laser beam which gives rise to less color dispersion is processed later in terms of scanning time than the intensity modulation video signal for a laser beam which gives rise to more color dispersion, more preferrably so later that the angle of deflection of the laser beam of one color substantially coincides with the angle of deflection for the laser beam of the other color.
With such an arrangement, the intensity modulation is so adjusted, that each of the laser beams is intensity-modulated differently from others in terms of scanning time to obtain substantially the same angle of deflection for all the color beams