Wolfe S M, Button K J, Waldman J, Cohn D R
Appl Opt. 1976 Nov 1;15(11):2645-8. doi: 10.1364/AO.15.002645.
A high resolution submillimeter interferometer system for measurement of electron densities in the 10(14)-cm(-3) </= n(e) </= 2 x 10(15)-cm(-3) range has been developed for use in high density tokamaks. Phase modulation at ~1 MH(z) is accomplished by difference frequency mixing of two cavity tuned laser oscillators. The optically pumped CH(3)OH lasers, which operate on the 118.8-microtm line, feature a novel output coupling design that permits good mode quality and low beam divergence. The beat signals are detected using a newly developed Ge:Li photoconductor, and a direct measurement of the phase shift is obtained from the time lag between probe and reference signals. The sensitivity of the resulting phase measurement is independent of the instantaneous phase and unaffected by fluctuations in the amplitude or in the frequency of the modulation.
已开发出一种用于高密度托卡马克的高分辨率亚毫米波干涉仪系统，用于测量电子密度范围为10¹⁴厘米⁻³ ≤ n(e) ≤ 2×10¹⁵厘米⁻³的情况。通过两个腔调谐激光振荡器的差频混频来实现约1兆赫兹的相位调制。工作在118.8微米谱线的光泵浦CH₃OH激光器具有一种新颖的输出耦合设计，可实现良好的模式质量和低光束发散。使用新开发的锗锂光电导体检测拍频信号，并根据探测信号和参考信号之间的时间延迟直接测量相移。所得相位测量的灵敏度与瞬时相位无关，不受调制幅度或频率波动的影响。
