New Laser Interferometer with OPD Multiplication for Nanometer Measurement

By using coupled differential interferometry a new laser displacement measurement interferometer with nanometric accuracy has been developed. The resolution and the stability of the interferometer are improved by multiplicating the optical path difference (OPD). The new interferometer is simple in concept,symmetric in optical paths,without optical deadpath,easy to set up and align. λ/1600 resolution and nanometric accuracy are achieved within the measurement range of 10 mm.