基于自混合干涉技术和双调制方法的振动测量

Vibration measurement based on self-mixing interference technique and double modulation method

为了测量物体的微振动,提出一种基于自混合干涉(SMI)技术的新型调制方法--双调制。信号发生器产生正弦波输入到激光二极管(LD)控制器中,形成电流调制;三角波驱动电光调制器(EOM)实现相位调制;将两种调制方法相结合形成双调制技术。首先,用双调制方法调制物体未振动时的SMI信号,并使用五步相移算法解调;然后,用双调制方法与五步相移算法对物体振动时的SMI信号进行调制与解调,根据物体未振动和振动时的相位得到只由振动引起的相位,进而重构振动物体的微位移。实验结果表明:对峰峰值为2 000nm、频率为10Hz的正弦振动进行测量时,得到的最大重构误差为79.3nm。

In order to measure the micro-vibration of an object,a new modulation method based on self-mixing interference(SMI)technology,double modulation,is proposed.A signal generator is used to generate a sine wave input into a laser diode(LD)controller to form a current modulation;a triangular wave is used to drive an electro-optical modulator(EOM)to achieve phase modulation;and the two modulation methods are combined to form a double modulation technique.First,the SMI signal is modulated by the double modulation method and demodulated using the five-step phase shift algorithm when the object is not vibrating.Then,the SMI signal is modulated and demodulated by the double modulation method and the five-step phase shift algorithm when the object vibrating.The phase caused by the vibration is obtained according to the phase when the object is not vibrating and vibrating,and the micro-displacement of the vibrating object is reconstructed.The experimental results show that the maximum reconstructed error of the sinusoidal vibration with a peak-topeak value of 2 000 nm and a frequency of 10 Hz is 79.3 nm.