Measurement of two-dimensional small rotation angles by using orthogonal parallel interference patterns

Abstract

Based on measuring one-dimensional small rotation angles by using a parallel interference pattern (PIP), a method for measuring two-dimensional (2D) small rotation angles by using two different PIP's that are orthogonal to each other is proposed. We simultaneously measure the 2D small rotation angles Δθ and Δφ by detecting the phases of the orthogonal PIP's reflected by an object at two detection points. A sensitivity of 4.9 mrad/arcsec and a spatial resolution of 1.5 × 1.5 mm(2) are achieved in the measurement. Theoretical analysis and experimental results show that error ε(1) in the measurement of Δφ is almost equal to -0.01Δθ and error ε(2) in the measurement of Δθ is almost equal to -0.01Δφ. For small rotation angles of less than a few tens of arcseconds, the random errors whose standard deviations are 0.6 arcsec are dominant.

Large angular range carousel interferometer for spectroscopic applications

“…Angle measurement techniques are important in optical interferometry, optical processing, metrology and spectroscopy [1][2][3][4][5][6][7][8][9][10][11]. In these techniques optical path difference (OPD) at the output port is created using assembly of rotating mirrors which is inherently a nonlinear function of rotation.…”

“…The intensity recorded by the detector for a monochromatic source is (1) For polychromatic beam of light (2) where I(σ) is the intensity of the light source as a function of wave number σ while x is the OPD. The real signal can be obtained by inverse Fourier transform.…”

“…Mirrors M 1 -M 4 are1 The article is published in the original. a rotating body while end-mirrors M 5 , M 6 and beamsplitter BS are placed on a static platform.…”

High-precision technique for in-situ testing of the PZT scanner based on fringe analysis

“…In recent years, newer techniques, such as fringe-analysis techniques [11], Lau interferometry [12], fringe projection [13,14], and the circle Dammann grating [15], have been also developed for angle measurement.…”

Wide-range two-dimensional small rotation-angle measurement by use of fringe projection

“…The orthogonal PIPs and two PIPs enabled us two-dimensional 4 and wide range 5 rotation-angle measurement, respectively, by eliminating external disturbance. Although these systems are able to realize high accurate and wide-range rotation-angle measurement, they become complicated and large.…”