Abstract: On an essentially non-absorbing plate located in the focal plane of a laser beam to be adjusted, a plurality of marks is arranged in a definite pattern. The marks deflect the laser light incident upon them by refraction, scattering, diffraction or otherwise, and direct the deflected light onto one or several laser detectors. The detectors convert the light received into corresponding electrical signals which may used for the fine adjustment of the laser beam by an evaluating electronic device.

Abstract: In the resonator of a laser generator, variable mode selective structure is provided to permit electrically actuated adaptation of beam parameters to required operating conditions. Such structure can be implemented with one or more pivotal plates, each having a different aperture, that are selectively pivoted into the beam path to effectively provide a variable mode diaphragm. In another embodiment, a spatial light modulator comprising a reversing prism with a variable position concave plate positioned adjacent its reflection surface and operating according to the optical tunnel effect can be used to selectively vary the effective diameter of the laser beam.