Heterodyne interferometer with unequal path lengths
نویسندگان
چکیده
Laser interferometry is an extensively used diagnostic for plasma experiments. Existing plasma interferometers are designed on the presumption that the scene and reference beam path lengths have to be equal, a requirement that is costly in both the number of optical components and the alignment complexity. It is shown here that having equal path lengths is not necessary, instead, what is required is that the path length difference be an even multiple of the laser cavity length. This assertion has been verified in a heterodyne laser interferometer that measures typical line-average densities of 1021/m2 with an error of 1019/m2. © 2006 American Institute of Physics. DOI: 10.1063/1.2336769
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