Abstract: In a process for generating at least three laser beams of different wavelengths for displaying color video pictures, a pulsed laser is used to generate light. The light output of the pulsed laser is released in a pulse and is introduced into a medium with nonlinear optical characteristics for generating a laser beam. In addition to the laser beam generated by excitation, this medium releases an additional laser beam whose frequency is given by the sum or difference frequencies of the exciting laser beam and the excited laser beam due to the nonlinear optical characteristics of the medium. The laser beams generated by the medium in this way and the exciting laser beam are used directly, or after frequency conversion, to display monochromatic partial images of a color video picture. An apparatus according to the invention contains suitable devices for carrying out the process.

Abstract: In a device with a laser for image presentation in which the laser emits laser light of a defined coherence length L at a given wavelength .lambda. and in which there is arranged in the path of the laser light a first structure with which phase displacements can be carried out for individual photons of the laser light in accordance with a predetermined distribution, it is provided that the average path given by the ratio of the average root mean square of the phase displacement formed by the distribution and the magnitude of the wave vector k=2.pi./.lambda. of the laser is greater than the coherence length L multiplied by a factor of 1/(12).sup.1/2.

Abstract: In a process for generating at least three laser beams of different wavelengths for displaying color video pictures, a pulsed laser is used to generate light. The light output of the pulsed laser is released in a pulse and is introduced into a medium with nonlinear optical characteristics for generating a laser beam. In addition to the laser beam generated by excitation, this medium releases an additional laser beam whose frequency is given by the sum or difference frequencies of the exciting laser beam and the excited laser beam due to the nonlinear optical characteristics of the medium. The laser beams generated by the medium in this way and the exciting laser beam are used directly, or after frequency conversion, to display monochromatic partial images of a color video picture. An apparatus according to the invention contains suitable devices for carrying out the process.