双波长集成光栅干涉微位移测量方法

介绍了一种基于双波长激光的集成光栅干涉位移检测方法,利用该方法对硅-玻璃键合工艺制作的集成光栅位移敏感芯片进行了测试实验。实验系统主要由敏感芯片、波长为640nm和660nm的双波长半导体激光器、双光电二极管及检测电路组成,敏感芯片则由带反射面的可动部件和透明基底上的金属光栅组成。入射激光照射到光栅上产生衍射光斑,衍射光的光强随可动部件与光栅之间的距离变化,通过分别测量两个波长的衍射光强信号并交替切换选取灵敏度较高的输出信号,实现了一定范围内的扩量程位移测量,并得到绝对位置。实验结果表明,利用双波长集成光栅干涉位移检测方法测得敏感芯片可动部件与基底光栅的初始间隙为7.522μm,并实现了间隙从7.522μm到6.904μm区间的高灵敏度位移测量,其噪声等效位移为0.2nm。

Displacement measurement method based on integrated grating interferometry with two-wavelength lasers

A displacement detection method based on two-wavelength grating interferometry was presented. A measurement experiment was carried out by using an integrated grating sensor chip fabricated by silicon-glass bonding bulk process. The measurement setup consisted of a sensor chip, two lasers with wavelengths of 640 nm and 660 nm, two photodetectors and a data acquisition circuit. The sensor chip included moving parts with a reflective surface and a metal grating on the transparent substrate. In experiment, the laser beam illuminated the grating and the grating reflected the laser beam to form a diffraction pattern. As the intensity of the diffracted beams changed according to the displacement between movable structure and substrate, the displacement could be determined with an extended range than single wavelength and the absolute position could be obtained by measuring intensity signals of the two wavelengths respectively. Experimental results show that the initial gap between the moving part and the substrate is about 7.522 μm measured by proposed method and it can implement the displacement measurement in a range of 618 nm with a resolution of 0.2 nm.