Abstract: An apparatus for generating coherent radiation at a desired frequency is disclosed. In a preferred embodiment the apparatus comprises: an injection-locked semiconductor diode structure having a large active area for emitting a diffraction-limited beam at a preselected frequency; optics for focusing the diffraction-limited beam into a focused beam; a nonlinear crystal responsive to the focused beam for producing a beam of laser power which includes an output beam at a desired harmonic of the preselected frequency; and a device for passing the output beam in a given direction. In a modification of the preferred embodiment, the output of the injection-locked semiconductor diode structure is mixed with an emission from a laser source in the nonlinear crystal to produce a desired sum or difference frequency.

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 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 for far field correction. The filter employs two lenses of birefrigent 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 two lenses may be both spherical or both cylindrical.The correction provides an improvement in beam quality in laser systems operating with larger beam apertures or at higher powers.

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: The invention deals with a face pumped slab laser in which the slab is of a rectangular configuration, favoring use of an optical resonator cavity capable of producing a rectangular beam of good quality within the cavity. The novel optical resonator cavity, which produces this rectangular beam, is stable on one axis corresponding to the smaller beam dimension and unstable on an axis orthogonal to the first axis corresponding to the larger beam dimension. The result is both high efficiency, excellent power and a good quality output beam is produced.