介绍了2m比长仪系统的组成,对其采用光电显微镜动态瞄准刻线和激光干涉测长原理进行了分析,研究了提高刻线瞄准精度和激光干涉测长精度的方法及利用现代电子技术实现刻线信号和干涉信号自动同步快速处理方法.自动信号处理系统基于FPGA现场可编程电路技术和计算机技术.通过对金属线纹尺测量的实验表明,依据JJG 331-1994激光干涉比长仪检定规程进行实验,2m比长仪单次最佳刻线瞄准精度优于10 nm(1σ),对其测量的不确定度分析表明,对于测量高质量的高等别线纹尺,其测量不确定度U=(20 +40 L)nm(k =2).%The components of 2 m Length Comparator are described. The principle of line space dynamic measurement with photoelectric microscope and laser interferometer is analyzed. The methods for improving the accuracy of line positioning and line space measurement are studied,and the methods for automatically and synchronously processing of line signal and interference signal with high speed are studied also. The signal processing system is based on integrate circuit FPGA and computer techniques. The experiment,according to Verification Regulation JJG 331-1994 (China) :the interference length comparator, was performed for measurement of standard metal line scale. The result shows that the best standard deviation of position for line with good quality is less than 10nm,and the measurement uncertainty analysis for the line space shows that,when measuring high quality line scale,the expanded measurement uncertainty U = (20 + 40L) nm,k=2.
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