基于衍射光栅计量系统的非接触轮廓测量位移传感器

Non-contact Displacement Sensor with Diffraction Grating Metrology System for Profile Measurement

聚集检测法是一种非接触轮廓测量方法,但是现有的聚焦检测法采用音圈电机,其测量精度有限。针对此问题,文中提出了一种非接触位移传感器,该传感器基于改进的傅科聚焦检测法,并带有衍射光栅计量系统。通过压电驱动器取代音圈电机驱动,并配合位移计量系统,提高了传感器的测量精度。在表面轮廓采样时,根据聚焦偏差信号,压电驱动器驱动聚焦透镜作垂直运动,使焦点始终在工件表面,同时衍射光栅计量系统测得聚焦透镜的垂直位移并将其作为采样点的轮廓高度。所有采样点的位移显示出被测量表面的整个轮廓,评定软件处理这些位移数据即可获得测量结果。该非接触的位移传感器的分辨率为10 nm.

Focus detection method is one of the non-contact profile measurement methods. However, the measurement accuracy of current focus detection method is limited by voice coil motor adopted by it. This paper presented a new non-contact displacement sensor with diffraction grating metrology system based on an improved Foucault focus detection method. Driven by a piezoelectric actuator instead of a voice coil motor, and a diffraction grating metrology system being with it, the sensor has high measurement accuracy. During surface profile sampling, according to focusing deviation signal, the focusing lens is driven to move vertically by the piezoelectric actuator so that its focus is always located on the work piece surface ; synchronously the vertical displacement of the focusing lens is obtained by the diffraction grating metrology system as the profile height of sampling points. The displacements of all sampling points show the whole profile of the measured surface, which can be processed by characterization software to obtain the measurement result. The solution of this non-contact displacement sensor is 10 nm.