Enhanced roll-angle measurement interferometer

Abstract

A roll-angle measurement interferometer with good stability and high sensitivity is presented. In the system, two sets of spatial parallel beams with different frequencies are formed with the help of a Koster prism, a corner cube, a quarter-wave plate, a wedge prism, and a wedge mirror. The wedge prism is used for the roll-angle sensing component, the roll of which will cause the changes of the optical path of the two beams with different frequencies. This interferometer complies with the principle of common path which minimizes the dead path; the cross talk of straightness, pitch, and yaw errors are avoided in this specific structure which enhances the stability and precision of the measurement. The experimental result fits well with the theoretical analysis and a measurement resolution of 2 μrad is achieved with an electronic interpolation of 2π∕512.

Investigation of heterodyne interferometer technique for dynamic angle measurement: error analysis and performance evaluation

“…Based on equation (10), the simulated result of ∆θ with σ is presented as figure 6(b), where colorbar denotes ∆θ. From this, it is clear that the calculated angle errors increase more obviously with an increase of the tilt error.…”

“…Zhang et al employed a laser heterodyne interferometer based on Faraday effect to measure rotation angle and yaw angle [9]. Furthermore, a roll angle measurement interferometer is proposed to achieve a measurement resolution of 2 µrad (circa 0.413 ′′ ), in which one wedge prism and one wedge mirror are the core components [10]. Besides, several well-known manufactures have contributed their resource into developing angle interferometers.…”

Precision roll angle measurement based on digital speckle pattern interferometry

“…However, due to the insensitivity of traditional interferometry to the inplane roll displacement, usually a heterodyne interferometry with a cooperative target was used to measure the roll angle. This cooperative target, such as a halfwave plate [14][15][16] and wedge prism [17,18], is installed in the object and modulates the interferometric phase when the object rolls.…”