Layer H P, Deslattes R D, Schweitzer W G
Appl Opt. 1976 Mar 1;15(3):734-43. doi: 10.1364/AO.15.000734.
High resolution interferometry has been used to determine the wavelength ratio between two molecularly stabilized He-Ne lasers, one locked to a methane absorption at 3.39 microm and the other locked to the k peak of (129)I(2) at 633 nm. An optical beat frequency technique gave fractional orders while a microwave sideband method yielded the integer parts. Conventional (third derivative) peak seeking servoes stabilized both laser and cavity lengths. Reproducibility of the electronic control system and optics was a few parts in 10(12), while systematic errors associated with curvature of the cavity mirrors limited the accuracy of the wavelength ratio measurement to 2 parts in 10(10). The measured wavelength ratio of the methane stabilized He-Ne laser at 3.39 microm [P(7) line, nu(3) band] to the (129)I(2) (k peak) stabilized He-Ne laser at 633 nm was 5.359 049 260 6 (0.000 2 ppm). This ratio agrees with that calculated from the (lower accuracy) results of earlier wavelength measurements made relative to the (86)Kr standard. Its higher accuracy thus permits a provisional extension of the frequency scale based on the cesium oscillator into the visible spectrum.
高分辨率干涉测量法已被用于确定两台分子稳定的氦氖激光器之间的波长比，其中一台锁定在3.39微米处的甲烷吸收峰，另一台锁定在633纳米处的（129）I₂的k峰。光学拍频技术给出分数阶数，而微波边带法得出整数部分。传统的（三阶导数）峰值搜索伺服系统稳定了激光器和腔长。电子控制系统和光学器件的可重复性为10¹²分之几，而与腔镜曲率相关的系统误差将波长比测量的精度限制在10¹⁰分之二。测得的3.39微米[P(7)线，ν₃带]甲烷稳定氦氖激光器与633纳米（129）I₂（k峰）稳定氦氖激光器的波长比为5.359 049 260 6（0.000 2 ppm）。该比值与根据早期相对于（86）Kr标准进行的波长测量（精度较低）结果计算得出的比值一致。因此，其更高的精度允许将基于铯振荡器的频率标度临时扩展到可见光谱。
