Abstract: The invention relates to an electrooptical system mounted in a tunable laser cavity, made up of the association of passive and active birefringent components such as birefringent lenses (29) and electrooptical crystals (9), (10), (11) and (12) introducing a preset or adjustable optical-retardation as a function of the wavelength tuning range. The system is designed to be controlled by a small control voltage, and to tune the wavelength according to an arbitrary scanning law, with a tuning rate that can be high and with an adjustable emission line width.

Abstract: A neodymium or other rare earth doped solid state laser is pumped by a matched high efficiency laser diode, resulting in a compact, high efficiency and long lifetime laser assembly. Output is in the near infrared range, but can be converted to the visible spectrum by an intra-cavity frequency doubler. A doubling crystal, which may be a KTP crystal, is placed at an optimum location in the laser cavity. Polarization of the beam may be achieved simply by stressing a non-birefringent rod, prior to frequency doubling, or by using a birefringent material such as Nd:YLF for the rod. An amplitude noise suppression elaton may also be placed at an optimum position in the laser cavity; alternatively a ring cavity or pair of quarter wave plates can be used. A folded cavity configuration produces a pair of beam waists in the cavity. Pulsed operation can be produced by means of a Q-switch.

Abstract: The present invention deals with an optical transmission filter for effecting differential phase delay upon light in a beam polarized in a P dimension, as a function of position within the filter aperture. The filter employs two lenses of birefringent material, the crystal optic axes of the respective lens materials being oriented in mutually orthogonal positions and at a 45.degree. angle to the P dimension. The lenses have their adjacent surfaces respectively concave and convex with the same radius of curvature and their non-adjacent surfaces flat.The phase response of the filter is a function of the radial distance of a beam element from the filter axis with spherical lenses and a function of a linear coordinate distance from the filter axis with cylindrical lenses. A two-part construction for one lens, which permits adjustment of the difference in center thicknesses between the two lenses, allows adjustment of the differential phase delay with respect to a spacial reference.

Abstract: The output of a laser oscillator is doubly passed through a birefringement medium, a quarter-wave plate and a laser amplifier by reflection from a phase conjugate mirror, the birefringent medium being between the oscillator and the plate in the path of the initial and reflected oscillator output. The birefringent medium divides the oscillator output into a first set of orthogonal polarization components (rays) and refracts one of them at a first angle successively through the plate and amplifier for reflection from the mirror through the amplifier, plate and medium. The reflected ray is amplified and then divided by the medium into a second set of orthogonal ray components which exit the medium at different angles away from the oscillator. In another embodiment, a second quarter-wave plate is added between the amplifier and mirror, and in a third embodiment the amplifier is positioned between the oscillator and the birefringent medium.

Abstract: The invention is a switch to permit a laser beam to escape a laser cavity through the use of an externally applied electric field across a harmonic conversion crystal. Amplification takes place in the laser cavity, and then the laser beam is switched out by the laser light being harmonically converted with dichroic or polarization sensitive elements present to alter the optical path of the harmonically converted laser light. Modulation of the laser beam can also be accomplished by varying the external electric field.

Abstract: The present invention deals with an optical filter polarizer combination providing a spacial transmission function to polarized incident light. When the light is in the form of a beam the combination may be used to reject extraneous light, or to modify the intensity profile of the beam as a radial or as a linear spacial function (orthogonal to the axis of the beam). The filter employs two lens elements of birefringent materials, with their crystal optical axes mutually orthogonal, and at 45.degree. to the plane of polarization. Spherical lenses are employed for a radial spacial function and cylindrical lenses are employed for a linear spacial function. The combination is useful for mode selection in a stable laser oscillator, for beam quality improvement in a stable/unstable oscillator, and for fill factor enhancement in coupling energy from a laser oscillator to a laser amplifier.

Abstract: An improved laser tuner assembly of the type that includes a plurality of parallel, spaced-apart, birefringent plates comprises means for independently adjusting the orientations of the individual plates, clamping means for demountably securing the positions of the individual plates without substantially altering their orientations, and means for rotating the plates as a unit to tune the laser. The tuner permits simple and reproducible orientation of the plates. In a preferred embodiment, tuning is electronically controlled and motor driven.

Abstract: An unpolarized electro-optically Q-switched laser using a laser rod (4), a prism (1) and a Pockels cell (5) between a pair of mirrors (2, 3) wherein the prism (1) is selected to give a low-angle walk-off arranged that when a quarter wave length voltage is applied to the Pockels cell the first pass will be cancelled by an equal and opposite walk-off during the return path.

Abstract: A laser system for providing a rapidly steerable laser output beam. The laser system includes a phase conjugate reflector, laser gain medium and its associated pump source, an output coupling device, and an optical element which selectably controls the transverse lasing mode of the laser system. The components are arranged to form a laser oscillator between the phase conjugate reflector and the optical device, and is operated in such a manner that each selected transverse mode of laser operation generates an output beam from the system which has a different wavefront tilt. Accordingly, the output beam is steerable and is dependent upon the selected transverse mode which is currently lasing in the oscillator.

Abstract: A laser output coupler utilizes a birefrigent lens which has one side thereof curved so as to present a non-uniform polarization distribution across the face of the lens. A polarized beam splitter is employed to separate the output beam from the feedback beam; the feedback beam having a non uniform distribution across the laser aperture enhances mode discrimination of a pulsed resonator.

Abstract: Thermally induced stress birefringence in laser resonators is eliminated by inserting a waveplate in the resonating cavity. The waveplate is chosen by matching its polarization transmission matrix to the polarization transmission matrices of the laser rod and a Porro prism used as an end reflector in the resonating cavity. This produces a total polarization transmission matrix in the resonating cavity which is independent of ray coordinates. Additional control of the polarization transmission matrix is provided using a Porro prism as a cavity reflector that has an antireflection coating on its roof to change the required phase advance angle of the waveplate.