PHASE MODULATION HOMODYNE INTERFEROMETER WITH PICOMETER RESOLUTION USING TUNABLE LASER DIODE

摘要

The method for measuring the displacement with high resolution by adjusting the optical frequency of the TLD is proposed. Its system is constructed by combining with the PMHI, the TLD and frequency tuning electronics. For measuring displacement optical path difference is determined by averaging FSR which is measured by observing the lock-in output when optical frequency scanned. Comparison measurement between proposed system and commercial heterodyne interferometer has carried out to evaluate performance of proposed system. From the experimental results, periodic error of commercial interferometer is detected. Its amplitude is less than 3nm and its period is about 310nm.