基于低速面阵CCD的正弦相位调制干涉测量

Sinusoidal Phase Modulating Interferometry Based on Low Frame Rate Area Array CCD

正弦相位调制（SPM）干涉测量技术用于表面形貌测量时，需要帧速高于300frame／s的图像传感器，同时要求调制信号频率与图像传感器帧速成确定的整数倍关系。提出一种基于低速CCD（30frame／s）的帧速可调的高速图像传感技术，通过控制每帧像素总数提高CCD帧速，研制出一种高帧速图像传感器，帧速可达300～1600frame／s，且每帧大小连续可调。将该CCD传感器用于正弦相位调制干涉泰曼一格林干涉仪，测量镀膜玻璃板表面形貌，当CCD图像传感器的帧速与调制信号频率呈16，8，4倍的关系时，得到玻璃板表面形貌的轮廓平均算术偏差Ra小于1．8nm，重复精度优于3nm。

In the sinusoidal phase modulating （SPM） interferometer technology for surface profile measurement, the high speed charge coupled device （CCD） of frame frequency greater than 300 frame/s is necessary to detect the interference signals, and the relationship between CCD＇s frame frequency and modulating frequency is needed to be integer multiple. A novel high-speed image sensing technique with adjustable frame rate based on an low speed CCD （frame frequency less than 30 frame/s） was proposed in this paper, which can be used to realize the surface profile measurement by the SPM interferometer. A high speed sensor was designed by controlling the number of pixels of every frame to improve the CCD frame rate, the frame rate is in the range of 300～1600 frame/s, and the frame size can continuously adjustable, which satisfies the sinusoidal phase modulation. The SPM interferometer with the CCD was used to measure the surface profile of glass plate, and the experiment results of the measurement accuracy under different frame rates were compared. When the frame rates are 16, 8, 4 times of the modulating signal, arithmetical mean deviation of the glass plate surface profile is less than 1.8 nm, and repeatability of the accuracy is superior to 3 nm.