Abstract:
A self-tuning optical notch filter is employed to separate coherent from noncoherent radiation in an overall beam. The presence of coherent radiation is detected, preferably with an interferometer, and the frequency of the detected coher ent radiation is determined. An electrical control signal is generated with a frequency corresponding to that of the coher ent radiation, and causes an optical filter to filter out the coherent radiation from the beam. In the preferred embodiment the optical filter is a Bragg cell, and the electrical control signal is applied to an electro-acoustic transducer which fur nishes an acoustic control signal to the Bragg cell.
Abstract:
An imaging coherent radiometer incorporating a Fabry-Perot interferometer which is scanned or nutated, for detecting and determining location and wavelength of coherent radiation or the coherent absence of radiation in the presence of non-coherent ambient radiation.
Abstract:
This invention relates to unequal path interferometers which are adapted, among other possible uses, for use in detecting coherent radiation as from a laser in a packet of radiation including incoherent background radiation, which includes an unequal optical path length interferometer of the type in which portions of the radiation impinging on the interferometric component are caused to be recombined after travelling two different optical paths; the optical paths differing in length by an amount substantially greater than the coherence length of the non-coherent radiation but substantially less than the coherence length of the coherent radiation; the unequal optical path length interferometric component including a crystalline cell having anisotropic properties; circuitry for applying an ultrasonic sound wave to the crystalline cell to vary the effective index of refraction of the crystalline cell in a preselected systematic manner; a detector for detecting the intensity of the recombined portions and producing a signal representative thereof, said signal having a variable component caused by the varying constructive and destructive interference of the recombined coherent radiation components, while the recombined non-coherent radiation components produce only a substantially steady background signal.
Abstract:
Interferometrische Meßsysteme sind bekannt. Sie enthalten eine Lichtquelle zur Erzeugung kohärenten Lichtes und einen Interferometeraufbau, bestehend aus mindestens einem Strahlteiler und zwei Reflektoren sowie Linsen zur Bündelung des Lichtstrahls. Erfindungsgemäß dient ein solches Meßsystem zur Untersuchung des von einer Laserlichtquelle (1) ausgesandten Lichtbündels (30) auf Frequenz, Moden, Modenstabilität, Modenverteilung sowie Kohärenzlänge und Kohärenzzeit etc. Das Lichtbündel (30) wird durch eine Linse parallel gemacht, gelangt anschließend über den Strahlteiler (3) in zwei Teilbündel (31, 32) zu den Reflektoren (4, 5). Einer der beiden Teilbündel durchläuft ein Referenz-Interferenzmuster (7). Beide Teilbündel (31, 32) interferieren miteinander und werden über ein optisches System zur Verringerung der numerischen Apertur einem Photoempfänger (10) zugeführt. Besonders vorteilhaft ist es, wenn möglichst viele optische Bauelemente, insbesondere die Linse (2) der Strahlteiler (3) die Reflektoren (4, 5) und das Referenz-Interferenzmuster (7) auf einem Block (6) monolithisch integriert sind.
Abstract:
An imaging coherent radiometer incorporating a Fabry-Perot interferometer which is scanned or nutated, for detecting and determining location and wavelength of coherent radiation or the coherent absence of radiation in the presence of non-coherent ambient radiation.
Abstract:
This invention relates to unequal path interferometers which are adapted, among other possible uses, for use in detecting coherent radiation as from a laser in a packet of radiation including incoherent background radiation, which includes an unequal optical path length interferometer of the type in which portions of the radiation impinging on the interferometric component are caused to be recombined after travelling two different optical paths; the optical paths differing in length by an amount substantially greater than the coherence length of the non-coherent radiation but substantially less than the coherence length of the coherent radiation; the unequal optical path length interferometric component including a crystalline cell having anisotropic properties; circuitry for applying an ultrasonic sound wave to the crystalline cell to vary the effective index of refraction of the crystalline cell in a preselected systematic manner; a detector for detecting the intensity of the recombined portions and producing a signal representative thereof, said signal having a variable component caused by the varying constructive and destructive interference of the recombined coherent radiation components, while the recombined non-coherent radiation components produce only a substantially steady background signal.