Abstract: A cathode ray tube is used to address a spatial light modulator. The light used to read the spatial light modulator is preferably passed through an acoustic optical tunable filter to enable the wavelength and intensity to be rapidly controlled to provide, for example, a multicolor display of variable intensity. This finds particular application in head-up displays for use by pilots of aircrafts.

Abstract: A tunable laser having a range of possible emission frequencies has a Bragg cell mounted inside its laser cavity such that only light passing through the Bragg cell without Bragg deflection will be emitted by the laser.

Abstract: An acousto-optic tunable filter, for laser tuning, comprises an acoustic transducer connected to one face of an anisotropic crystal or Bragg cell which is cut at such an angle relative to its optic axis that an acoustic wave projected into the crystal normal to the face causes wavelength-specific diffraction of an incident optic wave (from a laser amplifying element) which nearly, but not completely, satisfies the parallel-tangents phase matching condition, thus preserving a substantial angular field of view, the angle also being such that the diffraction is polarization-insensitive.