一种使用双棱镜的动态小角度测量方法

提出一种基于正切关系和相位调制技术的动态小角度测量方法。使用双棱镜组成干涉测量臂引导两束平行光至分束棱镜处干涉,通过提取携带被测信息的干涉信号的相位实现动态的小角度测量。由于采用位置探测器(PSD)对测量臂中两平行光束的间距进行测量,简化了测量方程,消除了装置中双棱镜必须对称放置的要求。通过正弦地改变半导体激光器的注入电流在时域内实现对干涉信号的相位调制,形成准外差干涉测量模式,提高了光程差的测量精度。实验验证了该方法的可行性,并讨论了影响小角度测量精度的误差因素。研究结果表明,基于该方法的动态小角度的重

A method is presented based on tangent relationship and phase modulation technique for dynamic small angle measurement. Two parallel beams reflected by a measurement arm composed of two prisms are directed into a beam splitter to form an interference signal which is analysed to obtain the measurement result of small angle. A position sensitive device (PSD) is used to measure the separations between the two parallel beams, the measurement equation is simplified and the symmetry requirement of the two prisms in the optical configuration is eliminated. The phase of interference signal is modulated in time domain by sinusoidally changing the injection current of a laser diode. This results in a quasi-heterodyne measurement mode, which increases the measurement accuracy of optical path difference. The method is experimentally demonstrated and the factors affecting measurement accuracy are discussed. The experimental results show the dynamic small angle can be measured with a repeatability of 10-8 rad order of magnitude.