Development of CO2 laser dispersion interferometer with photoelastic modulator

Akiyama, T.; Kawahata, K.; Okajima, S.; Nakayama, K.
October 2010
Review of Scientific Instruments;Oct2010, Vol. 81 Issue 10, p10D501
Academic Journal
A dispersion interferometer is one of the promising methods of the electron density measurement on large and high density fusion devices. This paper describes development of a CO2 laser dispersion interferometer with a photoelastic modulator for phase modulation. In order to make the dispersion interferometer free from variations of the detected intensity, a new phase extraction method is introduced: The phase shift is evaluated from a ratio of amplitudes of the fundamental and the second harmonics of the phase modulation frequency in the detected interference signal. The proof-of-principle experiments demonstrate the feasibility of this method.


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