双A/D采样的跨尺度光栅微纳测量算法与实现

Cross-scale micro-nano measurement algorithm and implementation of grating based on double A/D sampling

光栅通过细分实现高分辨率测量,光栅细分数与A/D转换位数有关。针对目前低价位A/D采样芯片存在的A/D转换位数高则采样速度低或A/D转换位数低则采样速度高的特点,提出了一种跨尺度的光栅微纳测量方法,该方法通过高速A/D采样实现光栅快速测量,通过高转换位数A/D采样实现慢速微纳测量。为解决双A/D采样与细分的跟踪问题,设计了基于双A/D采样的二路细分算法,一路为判定算法,判定算法是以高速A/D采样值作为细分采样值,另外一路为测量算法,测量算法中的细分采样值是动态分配的,当判定算法的细分值和细分增量值满足跟踪条件时,测量算法中的采样值为慢速A/D采样值,否则为高速A/D采样值。实验数据表明,采用上述测量方法,可以任意组合两种不同转换位数与采样速度的A/D芯片,以满足不同需求的跨尺度光栅测量要求。

Grating measurement with high-resolution is obtained by subdivision,which depends on the number of conversion bits of A/D.Considering the low price of chip that possesses high-conversion bits of A/D with low-speed sampling or low conversion bits of A/D with high-speed sampling,a cross-scale grating micro-nano measurement method is proposed,by which the rapid grating measurement is realized by high-speed A/D sampling and the slow micro-nano measurement is achieved by high-conversion bits A/D sampling.In order to solve the tracking problem of double A/D sampling as well as subdivision,a new subdivision algorithm based on double A/D sampling is designed.The new subdivision algorithm contains judging algorithm that uses the high-speed A/D sampling data as the subdivision sampling values and measurement algorithm that the subdivision sampling values are allocated dynamically.When the value of subdivision and incremental value of subdivision satisfy the tracking condition,the low-speed A/D sampling data are used,otherwise,the high-speed A/D sampling data are used.The experimental data show that by using the above measurement method and subdivision algorithm,two kinds of A/D chips with different conversion bits and sampling speed can be arbitrarily combined to achieve the different requirements of cross-scale grating micro-nano measurement.