基于光纤三波长激光自混合干涉的绝对距离测量系统

Absolute Distance Measurement System Based on the Self-mixing Interferometry of a Three-wavelength Optical Fiber Laser

研究了一种基于光纤三波长激光自混合干涉的绝对距离测量系统.系统中的光纤激光器包含三个独立的激光谐振腔,每个激光谐振腔都有作为增益介质的掺铒光纤,三个激光谐振腔利用光纤光栅作为反射镜及波长选择元件,光纤激光器能同时发出无模竞争的频率和功率都稳定的三波长激光.利用三波长激光的自混合干涉,以及干涉信号的相位小数重合方法,实现绝对距离测量.为实现绝对距离测量,三个波长中两相邻波长间距应为相等.实验中,两相邻波长间距约为10nm.系统对公称高度为11mm修正值不大于2.7μm的台阶高度进行测量,测量结果为11.000059mm.对13.000090mm绝对距离重复测量20次的标准差为4.4nm.

An absolute distance measurement system based on the self-mixing interferometry of a three-wavelength optical fiber laser has been presented and experimented.The optical fiber laser is consisted of three independent laser cavities and there is erbium-doped fiber as a gain medium in each laser cavity.The three laser cavities use fiber Bragg gratings as the reflectors and wavelength selectors,and three wavelengths have been emitted simultaneously.There is no laser mode competition between the three wavelengths so each of the three wavelengths has stable frequency and power.Absolute distance measurement can be realized based on the self-mixing interferometry of the three wavelengths and the coincidence of the phase decimal of the three wavelengths self-mixing interferometric signals.By the method of simulation analyzing,the difference between every two adjacent wavelengths should be equal approximately.In the experiments,the difference between every two adjacent wavelengths is about 10 nm.A step with the nominal height of 11 mm and the corrected value less than 2.7μm was measured by the system.The measurement result is 11.000 059 mm.The standard deviation of twenty times repeated measurements of the absolute distance 13.000 090 mm is 4.4 nm.