基于激光频率分裂的波片位相差测量方法

应用激光频率分裂技术可以测量波片的位相延迟。将波片插入到激光谐振腔内,使激光纵模产生分裂,分别探测由同级和不同级分裂纵模产生的相邻两个频差,就可以求得波片的位相延迟。这种方法只需测量频差而不依赖于任何机械量的测量,并可以将位相延迟的测量溯源到激光的波长上。实验表明,该系统的测量分辨率可达0.003°,多次重复测量的偏差在0.05°以下,系统不确定度对于厚度1.5mm的石英晶体1/4波片约为1′。

Phase retardation measurement of wave-plate based on laser frequency splitting technology

Laser frequency splitting technology can be used to measure phase retardation of a wave-plate.With the wave-plate inserted into a laser cavity to split longitudinal laser,its phase retardation can be calculated by detecting the frequency differences between the same order or the adjacent order split longitudinal modes.No mechanical parameters but only the frequencies of optical beats need to be measured,and the measurement can be traced to the wavelength of the laser.Experiments prove that a resolution of 0.003° and a repeatability of 0.05° can be ensured.For a quartz quarter wave-plate of 1.5mm thick,the incertitude of the system is about 1′.