High-precision two-dimensional angle sensor using a dot array of a diffractive optical element

Abstract

An angle sensor is developed for measuring two-dimensional (2D) angular displacement. A periodic 2D dot array was generated using a diffractive optical element, and the 2D incident angle of the collimated incident beam was obtained by detecting the multiple peak positions of the 2D dot array. This strategy can reduce random error and periodic nonlinearity effects effectively, and achieve higher precision comparing with a conventional autocollimation principle. Stability of readout of a prototype sensor was evaluated as less than 0.000 3 ′′ with averaging time of 8 s. When 2D angular displacements over ±100 ′′ were simultaneously measured by the prototype sensor and a commercial autocollimator, the maximum deviation was less than 0.11 ′′ .

High precision vertical angle measurement system for calibration of various angle sensors and instruments

“…This miniature autocollimator, tasked with measuring two-axis angular positions (Θ X and Θ Y ) of a reflective mirror, incorporates a diffractive optical element (DOE). The use of a DOE allows for achieving high measurement resolution, even when utilizing a lens with a short focal length [19].…”

“…After determining the peak position and diffraction order of each dot pattern, individual incident angles are calculated using this data, in conjunction with information on the focal length of the lens, wavelength of the LD, and effective pitch of the DOE. Averaging these incident angles enables the precise determination of the two-axis angular position of the reflective mirror [19].…”

“…Standard deviations, calculated from 100 readouts over approximately 10 s, were measured at 0.04 ′′ and 0.03 ′′ for the horizontal and vertical axes, respectively. Nonlinearity errors were also assessed through comparison with the reference autocollimator, revealing values within ±0.18 ′′ [19].…”