Locating reference points in interferometer - by additional evaluation of white light interference and null crossing evaluation of direct component-free signals

摘要

The method of producing null points in interferometric arrangements involves performing additional evaluation of white light interference signals. The direct component-free white light signal null crossing following the global max. is detected form the signal's rising edge having a higher potential than the preceding one. Digital signals produced from null crossings are combined sequentially so that pref. the third null crossing following the last rising edge pulse is used for reference point detection. USE/ADVANTAGE - For precise reference point location on a path of motion, e.g. in incremental length measurement system, over wide dynamic range.