Another quick idea is a cnc positioning stage that uses optical interfrerometry to measure distance moved. Really anything involving fast fringe counting in an

Another quick idea is a cnc positioning stage that uses optical interfrerometry to measure distance moved. Really anything involving fast fringe counting in an interference pattern. It might be something like a new fringe for every micron of movement, so tracking something moving 1 m/s will require fringe counting at about 1 MHz, and the ADC sampling rate will need to be several times this in practice because errors are cumulative.