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2. Optical heterodyne detection - Wikipedia

   en.wikipedia.org/wiki/Optical_heterodyne_detection

   By itself, the signal beam's energy flux, , is DC and thus erases the phase associated with its optical frequency; Heterodyne detection allows this phase to be detected. If the optical phase of the signal beam shifts by an angle phi, then the phase of the electronic difference frequency shifts by exactly the same angle phi.

3. Laser beam profiler - Wikipedia

   en.wikipedia.org/wiki/Laser_beam_profiler

   A laser beam profiler captures, displays, and records the spatial intensity profile of a laser beam at a particular plane transverse to the beam propagation path. Since there are many types of lasers— ultraviolet , visible , infrared , continuous wave , pulsed, high-power, low-power—there is an assortment of instrumentation for measuring ...

4. Spatial filter - Wikipedia

   en.wikipedia.org/wiki/Spatial_filter

   A spatial filter is an optical device which uses the principles of Fourier optics to alter the structure of a beam of light or other electromagnetic radiation, typically coherent laser light. Spatial filtering is commonly used to "clean up" the output of lasers, removing aberrations in the beam due to imperfect, dirty, or damaged optics, or due ...

5. Shearing interferometer - Wikipedia

   en.wikipedia.org/wiki/Shearing_interferometer

   Principle of the shearing interferometer. The shearing interferometer is an extremely simple means to observe interference and to use this phenomenon to test the collimation of light beams, especially from laser sources which have a coherence length which is usually significantly longer than the thickness of the shear plate (see graphics) so that the basic condition for interference is fulfilled.

6. Beam diameter - Wikipedia

   en.wikipedia.org/wiki/Beam_diameter

   is the centroid of the beam profile in the x direction. When a beam is measured with a laser beam profiler, the wings of the beam profile influence the D4σ value more than the center of the profile, since the wings are weighted by the square of its distance, x 2, from the center of the beam. If the beam does not fill more than a third of the ...

7. Coherent anti-Stokes Raman spectroscopy - Wikipedia

   en.wikipedia.org/wiki/Coherent_anti-Stokes_Raman...

   This periodic modulation can be probed by a third laser beam, the probe beam. When the probe beam is propagating through the periodically altered medium, it acquires the same modulation. Part of the probe, originally at ω pr will now get modified to ω pr +ω p-ω S, which is the observed anti-Stokes emission. Under certain beam geometries ...