Design and Experiment of Linear Diffractive Laser Encoder Systems

• Main Authors: Chen, Shih-Jui, 陳世叡
• Other Authors: Yeh, C. S.
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/05828730185827101976

碩士 === 國立臺灣大學 === 應用力學研究所 === 90 === In this dissertation a compact size linear diffractive laser encoder was designed and fabricated. In addition, a step-by-step alignment procedure was also accomplished. This newly developed laser encoder used a 780 nm wavelength laser diode as the light source and was composed of several sub-systems, which include a 1-x telescope, a diffractive grating scale, and a circular polarization interferometer. The circular polarization interferometer sub-system can decode the optical interference signals obtained from two twice diffracted beams, both of which has their frequency subjected to Doppler shifted due to grating scale displacement. With the compact mechanical design and the isothermal design arrived from the common base plate, this newly developed laser encoder is less sensitive to environmental disturbances. As this laser encoder retrieves the grating scale displacement information from the pitch of the grating scale and not from the laser source wavelength, it was found to be potentially less prone to have its measurement accuracy influenced by the frequency drift of the light source used. The performance of the compact diffractive laser encoder system was verified by using the HP5529A interferometer as the measurement reference.