用可移动激光器对Ｈｅ－Ｎｅ／ＣＨ_４激光的绝对频率进行比对在１９８３年召开的第１７届长度和重量单位全体会议上采用了新的米制定义，它以光速恒定假设为基础。与此相应出现不同的实现米测量方法，其中一种流行较广的方法是利用波长或频率已知的辐射源进行衍射比长。?.. Alignment of the absolute frequency of He-Ne / CH_4 lasers with a movable laser A new metric definition was adopted at the 17th LWP plenary in 1983, based on the assumption of constant light velocity. Correspondingly, different measurement methods for realizing meters have emerged. One of the more popular methods is the use of a radiation source of a known wavelength or frequency for diffraction ratio length. ? ..