Abstract: An acousto-optic filter utilizing the far-off-axis anisotropic Bragg diffraction comprising an optically anisotropic crystal in which a light beam of incidence travels in a direction making a large angle with the crystalline axis and an ultrasonic wave travels in a predetermined direction. In the acousto-optic filter using a paratellurite crystal, the wavelength of the visible light is tuned by changing the frequency of the ultrasonic wave in a low frequency range below 100 MHz. The ultrasonic power required for driving the acousto-optic filter is about 1/500 that of the so far known acousto-optic filters. The bandwidth of the transmitted light can be changed from several angstroms to several hundred angstroms by selecting the incident angle of the light.

Abstract: An acousto-optic filter utilizing the far-off-axis anisotropic Bragg diffraction comprising an optically anisotropic acousto-optic medium embodied by a paratellurite crystal. An ultrasonic wave generated by a transducer is propagated in a direction different from that of the wave front normal to make the light-sound interaction length in the medium elongate by slanting the bonding surface of the transducer to the crystal medium.

Abstract: In a high speed printing apparatus in which ions produced between electrodes, to which is applied a high voltage, are passed through mists of ink, and particles of ink adhere to the ions to cause the printing operation to be conducted, said apparatus is characterized in that the air is supplied in such a way that only the desired printing width is left between the recording paper and the ink mists.

Abstract: In a high speed printing apparatus of the type in which ions produced between electrodes carrying a high voltage are passed through a mist of ink to cause selective particles of the ink to effect printing, there is provided an air circulating system in which the air containing the mists of ink is recovered, treated and again transferred to the printing portion.

Abstract: An acousto-optic filter utilizing the far-off-axis anisotropic Bragg diffraction comprising an optically anisotropic acousto-optic medium embodied by paratellurite. The light entrance surface is slanted to the crystalline axis to make a light beam incident perpendicularly to the surface. The light exit surface is slanted to the direction of the entrance surface to minimize the dispersion of diffracted angle due to light wave length.