The study of phase-shift for optical encoder

• Main Authors: Yen-shao Liu, 劉彥劭
• Other Authors: Ching-fen Kao
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/65470430444342847546

碩士 === 明道大學 === 光電暨能源工程學系碩士班 === 99 === This paper adopts a new design index grating of optical linear scale based on Longitudinal Moiré Fringe Theory. The traditional linear scale couldn’t produce fine sinusoidal. This research mainly focus on designing index grating groove divides blocks as move to clear low frequency signal, to improve waveform and generate more complete sinusoidal signal for better analyzing. This experiment adopts a 850nm LED as an illuminant in order to generate directional light through lens. The grating with period 20 μm was collimated and incident as a Talbot effect at an angle of 90° into a index grating with period 20.35 μm. Besides, when the two optical grating through relative movement, the Moiré interference would be produced. Using constructed optical grating as a detected receiver, it would detect the circles of waveform. The fractional Talbot self-image of phase grating was produced and projected onto an amplitude index grating. The Moiré pattern was generated when the index grating of detector has been displaced from Pattern. To improve circles of second battle could eliminate high frequency signal, however, index grating groove divides blocks as move to clear third and fifth harmonic wave therefore, after simulating and practical measurement, it would modify the waveform into perfection.