An illuminator (e.g., laser) produces a light beam that partially passes through, and is partially blocked by, a mask contrastingly patterned via non-transparent and transparent portions. The mask-conformed light passes through a lens so that the mask's pattern is projected into fluid seeded with a luminescent substance, which illuminatively reveals an image of the mask's pattern. The light beam can also be expanded and/or diffused prior to reaching the mask. Instead of or in addition to transmi...

An optical velocimetry probe used in avionics. A measurement volume through which particles can pass is illuminated with a light beam. Light which is backscattered by the particles causes interference with a reference beam which is taken from the original beam. A photodetector detects the interference.

A three-axis, non-scanning, self-referenced laser air data sensing system comprises a support having three separate laser diodes providing beams of coherent light, which beams are directed toward separate beam expander mirrors. The expander mirrors reflect an expanding beam back toward a focusing mirror that focuses the beams along three diverging axes at known angles to each other at three separate locations in space. The focused beams form small detection cell regions through which particles i...

The invention relates to an optical measurement device designed notably to evaluate the velocity of an aircraft by detection of a Doppler shift. The device for measurement by optical probe comprises at least two light beams of different wavelengths .lamda.1 , .lamda.2, denoted as first beam and second beam, the device illuminating a reference medium MILREF (60) by the first beam and receiving a light echo Sr reflected back by the reference medium, and the device comprising: an optical coupler CO...

A method for identifying and determining the frequency of scattered radiation fringe patterns for applications such as particle or droplet sizing and laser Doppler velocimetery. The method utilizes a series of windowed Fourier transforms performed on an intensity profile of the scattered radiation to locate a segment where a fringe pattern is located on the intensity profile. A standard Fourier transform is then performed on the segment to determine a dominant frequency of the fringe pattern, fr...

A method is provided for adjusting a laser doppler anemometer (1-5) having an emitting optic (3) which emits at least two laser beams (7, 8), and a receiving optic (4) for gathering light scattered by dispersed particles. The method comprises the steps of coupling a laser light (17) into an output of the receiving optic to make a focal point (12) of the receiving optic visible on a spaced reference surface (13); adjusting the receiving optic with respect to the surface so that the focal point of...

A miniature laser Doppler probe includes a laser, lens, another lens with a diffraction grating etched thereon, and a focusing lens. The focusing lens focuses the diffraction grating on an interrogation volume which has the particles whose movement is to be detected.

A vehicle external recognition system is provided with: a relative position detecting section detecting an object ahead of a vehicle as a detected object to detect a relative position relationship between the detected object and the vehicle, a relative velocity calculating section calculating a relative velocity between the detected object and the vehicle based on the relative position relationship detected by the relative position detecting section by using an initial value that is preset, a ve...

A coherent laser radar device is described which comprises a laser source (11), and two or more transceivers (84) are optically connected to the laser source by optical fiber cables (42, 48, 82) that are routed through an optical routing means (80). A detection means (27) is also provided, and radiation received by the two or more receivers (84) can also be optically coupled to the detection means (27) by optical fiber cables (82, 86, 90).

A laser radar apparatus includes a mixer 12 for converting the frequency of an electric signal outputted from a photodetector 11 into a baseband frequency by using a modulating signal generated by an oscillator 2. The laser radar apparatus carries out a coherent integral of the electric signal whose frequency has been converted by the mixer 12, and measures the quality of scatterers which exist in the atmosphere from a result of the integral. As a result, even when the S/N ratio of the light sig...