Abstract: A lamp reflector includes a light reflecting surface having a transverse cross-section with at least one spiral curve therein beginning behind a light source and curving thereabout with an every increasing radius of curvature. Light striking the spiral curve is reflected around the light source in the direction of the increasing radius of curvature to a location forwardly of the light source. Such a reflector can be adapted for use with light sources of cylindrical, toroidal and spherical shape. The reflector can be adapted for use with a light source enclosed within a transparent or translucent envelope.

Abstract: A laser velocimeter (12) has a laser beam generator (18) for generating first and second laser beams (20, 22) having a waist (40) of reduced cross-section area. A first focusing lens (28) has a first focal length F1 for focusing the first and second laser beams (20, 22) so that their waists focused by the lens (28) intersect at a focal point (26) at which a measurement is to be made. A second focusing lens (30) is positioned between the laser beam generator (18) and the first focusing lens (28). The second focusing lens (30) has a second focal length F2. The second focusing lens (30) is positioned from the first focusing lens (28) at a distance corresponding to a sum of the first and the second focal lengths F1 and F2. A third focusing lens (36) having a third focal length F3 is positioned between the laser beam generator (18) and the second lens (30). The third lens (36) is positioned from the second lens (30) a distance corresponding to the sum of the second and third focal lengths F3 and F2.

Abstract: A laser Doppler velocimeter (LDV) system (10) has a laser (12), a waist position adjusting lens (13), and a beam splitter (15), which direct laser beams (14) parallel to optical axis (16) of negative lens (18). Negative lens (18) is fixed relative to afocal lens pair (24,26). A pair of planar mirrors (20, 22) intersect at right angles and respectively intersect optical axis (16) and optical axis (28) of the afocal lens pair. Mirrors (20, 22) are movable along optical axis (28) toward and away from afocal lens pair (24, 26) to focus laser beams (14) in focus area (30) while maintaining a constant beam waist, crossing angle and intersection with other laser beams to produce a constant sensitive volume as the focus is changed.

Abstract: A laser Doppler velocimeter for measuring the velocity of a flowing fluid comprising laser means for providing first and second beams of collimated coherent monochromatic electromagnetic radiation which are focused to intersect at a predetermined location in a flowing fluid, the movement of the particles of the fluid serving to scatter radiation in substantially all directions, the scattered radiation being shifted in frequency from that of the first beam by an amount corresponding to the velocity of the fluid at the predetermined location, a corner cube disposed generally forward of the predetermined location, the corner cube responding to a portion of the radiation scattered in the forward direction and being operative to reflect the portion in a direction substantially antiparallel to the forward direction, and a collector responsive to the frequency of the first beam and to the frequency of the reflected portion of radiation and operative to provide a frequency modulated signal representative of the veloc