对圆光栅直径误差的光电检测,目前有的单位采用直流放大测试系统;有的则采用交流放大测试系统。采用直流放大系统测试,其检测结果可以反映出被测盘的综合误差(包含分度误差、均匀性误差等)。这项综合误差,对多数使用部门来说,是十分乐意接受和希望能得到的指标。采用交流放大系统测试时,均匀性误差反映到直径误差中的程度,显然没有直流放大系统测试时反映到直径误差中的大。交流系统影响的程度随其耦合网络时间常数τ的大小不同而不同;而直流系统测试时,均匀性误差基本上是一比一地反映到直径误差当中去。我们知道,均匀性误差的引起,同被测圆光栅线条宽窄变化、乳剂层厚薄不一致,以及线条区域黑白点等疵病有关。它们可归结为在整个刻划区域上,造成通光量的不一致而引起光电信号有变化。在电子线路中反映出来的是直流电平有起伏,从而引起相应的角度误差。我们通过反复实验证明,对同一块圆光 Photoelectric detection of the diameter of the circular grating error, there are some units using DC amplification test system; while others use AC amplification test system. Using DC amplification system testing, the test results can reflect the measured disk integrated error (including indexing error, uniformity error, etc.). This combined error, for most users, is a sign that is very receptive and hopefully available. When using the AC amplification system test, the uniformity error is reflected in the degree of the diameter error. Obviously, there is no large diameter error reflected in the DC amplification test. The degree of influence of the AC system varies with the magnitude of the time constant τ of the coupled network. When the DC system is tested, the uniformity error is basically reflected in the diameter error one by one. We know that the uniformity error is caused by the variation of line width of the tested circular raster, inconsistency of the thickness of the emulsion layer and defects such as black and white spots in the line area. They can be attributed to the entire scribe area, resulting in the inconsistency of light caused by optical signals have changed. Reflected in the electronic circuit is the DC level ups and downs, causing the corresponding angle error. We proved through repeated experiments that the same piece of round light