An evaluation of a modulated laser encoder

This paper introduces a new method of interpolation for sub-nanometer-resolution linear encoders. This method, called SPPE (scanning position probe encoder), uses high-order harmonics information obtained by a sinusoidal scanning pickup located on a periodic grating surface. The proposed encoder use...

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Bibliographic Details
Published inPrecision engineering Vol. 35; no. 2; pp. 302 - 308
Main Authors Makinouchi, Susumu, Watanabe, Akihiro, Takasaki, Masahisa, Ohara, Tetsuo, Ong, JinHock, Wakui, Shinji
Format Journal Article
LanguageEnglish
Published New York, NY Elsevier Inc 01.04.2011
Elsevier
Subjects
Applied sciences
Coders
Diffraction gratings
Encoders
Exact sciences and technology
Grating interferometer
Gratings (spectra)
Interpolation
Interpolation error
Lasers
Linear encoder
Mechanical engineering. Machine design
Phase detection
Position sensor
Precision engineering, watch making
Robustness
Scanning
SPPE
Position sensor
Linear encoder
SPPE
Grating interferometer
Interpolation error
Phase detection
Optical interferometry
High resolution
Precision engineering
Injection laser
Wavelength
Phase locked loop
Optical arrays
Laser interferometer
Nanometer scale
Diffractive optics
Displacement measurement
Position measurement
Robustness
Read head
Nanotechnology
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Summary:This paper introduces a new method of interpolation for sub-nanometer-resolution linear encoders. This method, called SPPE (scanning position probe encoder), uses high-order harmonics information obtained by a sinusoidal scanning pickup located on a periodic grating surface. The proposed encoder uses a current-modulated laser diode with diffractive grating optics. Since the electrical current changes the laser-diode wavelength, the interference light intensity is modulated as a sinusoidal scanning pickup on the scale grating. Phase-detection circuits can decode the position information in the pickup signal by using phase-locked loop techniques. The decoder achieves an interpolation rate of over 1/40,000 with interpolation errors of less than ±1 nm. A new interpolation-error measuring system was developed for the encoder. Finally, the evaluation results reveal that the presented encoder shows both high resolution and strong robustness.
Bibliography:ObjectType-Article-2
SourceType-Scholarly Journals-1
ObjectType-Feature-1
content type line 23
ISSN:0141-6359
1873-2372
DOI:10.1016/j.precisioneng.2010.11.008