Abstract: A singlet telescope is provided for reshaping the laser beam to a larger or smaller diameter while maintaining the inherent quality of the beam. Applications for the singlet telescope include intercavity expansion to accommodate the damage thresh-old of various components, expansion of beams to match the size of different wavelengths for final collimation, and shrinking of beams to provide high irradiance for nonlinear processes such as optical parametric oscillation and frequency doubling, with the above applications usually requiring low power magnification or demagnification. Problems involving the utilization of these telescopes over wide temperature ranges and ghost reflections in which a light is reflected back to a pumping laser are minimized with the singlet construction, with the ghost reflections potentially creating damage of components including self-damage or breakdown of air, as well as damage to a Q-switched resonator which causes pre-lasing.

Abstract: An optical tracker includes a plurality of detectors (20, 22), each of which is associated with an etendue-preserving concentrator (27, 28) that directs radiation to it. The concentrators (27, 28) associated with complementary detectors (20, 22) are oriented at angles with respect to each other such that their complementary angle-sensitive regions overlap. As a consequence, the outputs of the detectors can be used to aim the tracker even though the concentrators direct radiation to the detectors in a non-imaging manner.

Abstract: This optical velocimeter may be installed in an aircraft to measure the true airspeed and the angles of attack and of sideslip of the aircraft. Alternatively, the velocimeter may be mounted in a wind tunnel to measure the velocity of the airstream passing through the wind tunnel. In either case, the points of reference for measurement are the large number of aerosol particles that are entrained in the air and are assumed to have the same velocity as the oxygen and nitrogen molecules of the air itself.The velocimeter comprises a plurality of optical transmitters and optical receivers. Each transmitter includes a laser operated in the continuous-wave mode and a laser operated in the pulsed mode. The laser operated in the continuous-wave mode generates a "precursor light sheet" at some distance from the aircraft whose velocity is to be measured or in the wind-tunnel airstream whose velocity is to be measured.

Abstract: A dual-section spatial modulator transmitter consists of a collector surrounding a source of radiation to collect the energy from the source and form it into multiple beams. The collector is configured in two sections, a rotatable section and a stationary section such that spatial modulation is obtained by rotating only the rotatable section.

Abstract: A radiation system consists of a compound collection/beamforming system, surrounding a source of radiation, including an elevation collector/beamformer shaped as a compound parabolic concentrator and an azimuth collector/beamformer shaped so that tangential rays emanating from the source will be collected and formed into a beam of a predetermined design, and a modulator for alternately blocking and unblocking the beam from the compound collection/beamforming system.

Abstract: An optical system to permit two detectors to see the same field of view includes an angle converting cone, for mixing radiation from a field of view so that it can be applied to two detectors, and a lens for focusing the radiation onto the cone.

Abstract: An optically pumped solid-state laser system includes a rod (50) of laser material and a plurality of flashlamps (66) for pumping the laser. A surface for reflecting radiation from the flashlamp (66) to the rod (50) follows a set of curves (96). Each curve (96) is the locus of points whose distances outside the rod (50) and the lamp (66) to a pair of starting points on the other side of a base line (74) are a constant value such that the locus includes a lamp cusp (70).

Abstract: An optical element includes an ogival reflective surface which diverges an incident radiant energy beam substantially uniformly into a 2.pi. solid angle. The precise shape of the reflective surface is defined mathematically in relation to the desired solid angle of divergence and energy distribution of the incident beam. To facilitate mounting and alignment of the reflective surface in an optical system, it is formed internally of a body of optically transmissive material. The external surface of the transmissive body is shaped so as to provide normal incidence for rays reflected from the reflective surface. The element may be used as a beam diverger, or alternatively in reverse, to converge and collimate radiation.

Abstract: An improved knife edge system which enables testing of even high numerical aperture optics is achieved by using a microscope objective to gather the light from a small pinhole and fill a large optic under test, and in conjunction with a special eye piece permits viewing of the surface of the optic under test.

Abstract: Improved laser system gain is achieved by using Gadolinium to totally replace the Yttrium in a Lithium Yttrium Fluoride (YLF) host crystal so as to increase the amount of Neodymium which can be doped into the host crystal.

Abstract: A wide field of view-narrow band detection system including a radiation responsive member and optical filter is provided by employing optimal angle cones to simultaneously control field of view, throughput and angles impinging on the optical filter.

Abstract: In one embodiment, cooling of a laser passive Q-switch is provided by affixing the Q-switch to the rear mirror of the laser which, thus, acts as a heat sink for the Q-switch.

Abstract: A beam projector is provided by a plurality of coded reticles mounted on a spinning disc and illuminated by a laser source. In order to maintain a constant irradiance on a receiver variably located in space a pseudo-zoom assembly is provided including a moveable source and/or condenser optics. Also, plural focal length optics are employed to expand the range over which the constant irradiance is maintained beyond that realizable by the pseudo-zoom assembly itself.