Open AccessTwo-probe optical encoder for absolute positioning of precision stages by using an improved scale grating
Author(s) -
Xinghui Li,
Huanhuan Wang,
Kai Ni,
Qian Zhou,
Xinyu Mao,
Lijiang Zeng,
Xiaohao Wang,
Xifeng Xiao
Publication year - 2016
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.24.021378
Subject(s) - encoder , grating , optics , computer science , rotary encoder , displacement (psychology) , position (finance) , interferometry , linearity , algorithm , physics , psychology , finance , quantum mechanics , economics , psychotherapist , operating system
In this paper, a novel optical encoder enabling the simultaneous measurement of displacement and the position of precision stages is presented. The encoder is composed of an improved single-track scale grating and a compact two-probe reading head. In the scale grating, multiple reference codes are physically superimposed onto the incremental grooves, in contrast to conventional designs, where an additional track is necessary. The distribution of the reference codes follows a specific mathematical algorithm. For the reading head, a two-probe structure is designed to identify the discrete reference codes by means of the superimposition of the codes with a stationary mask and to read the continuous incremental grooves by means of a grating interferometry, respectively. A prototype encoder was designed, constructed and evaluated, and experimental results show that the distance code precision achieved is 0.5 μm, while the linearity error of the linear displacement measurement is less than 0.06%.