Abstract

Modern computer-controlled manufacturing machinery requires the absolute and highly accurate measurement of the linear position. Such an absolute, optical linear position encoder is described here. It is based on the transilluminance of a glass scale with an inexpensive light-emitting diode. The scale has two code tracks, one based on a pseudo-random binary sequence for the coarse determination of position and another periodic code for accurate fine-position measurement. A single-lens telecentric optical system images the code tracks in a mechanically insensitive way onto a custom photodetector. This special detector IC is capable of determining the components of the (complex) Fourier transform for the spatial frequency of the periodic code. The absolute optical position encoder shows a resolution of 10 nm and an absolute accuracy of better than 100 nm over short distances, verified with a commercial laser interferometer.

© 1996 Optical Society of America

High-resolution optical position encoder with large mounting tolerances

Kai Engelhardt and Peter Seitz
Appl. Opt. 36(13) 2912-2916 (1997)

Two-probe optical encoder for absolute positioning of precision stages by using an improved scale grating

Xinghui Li, Huanhuan Wang, Kai Ni, Qian Zhou, Xinyu Mao, Lijiang Zeng, Xiaohao Wang, and Xiang Xiao
Opt. Express 24(19) 21378-21391 (2016)

Diffractive incremental and absolute coding principle for optical rotary sensors

David Hopp, Christof Pruss, Wolfgang Osten, Jonathan Seybold, Karl-Peter Fritz, Tim Botzelmann, Volker Mayer, and Heinz Kück
Appl. Opt. 50(26) 5169-5177 (2011)

High-precision detection method for the reference position in an optical encoder

Jun Akedo, Yoshiaki Kato, and Hiroshi Kobayashi
Appl. Opt. 32(13) 2315-2319 (1993)

Performance of an optical encoder based on a nondiffractive beam implemented with a specific photodetection integrated circuit and a diffractive optical element

Fernando Perez Quintián, Nicolás Calarco, Ariel Lutenberg, and José Lipovetzky
Appl. Opt. 54(25) 7640-7647 (2015)