Compact optical roll-angle sensor with large measurement range and high sensitivity

Abstract

A simple and effective optical roll-angle sensor based on a magnetic garnet single crystal is demonstrated. The measurement is based on the principle that, when linearly polarized light whose polarization varies alternately in two orthogonal directions passes through a polarization analyzer, the transmitted optical intensity varies. The output voltage from an optical detector located after the analyzer can be used to determine the roll angle. The chief advantages of the sensor are that it is compact, flexible, low cost, and power effective and provides a fast response. Most importantly, the sensor is insensitive to various fluctuations such as optical intensity, photodiode responsivity, and temperature and to vibrations. This performance is most advantageous in long-distance or long-term measurements. Experimental results have shown that the angular resolution is 0.01 degree in a +/-30 degree range.

A high sensitive roll angle interferometer

“…Of all the six degree-of-freedom geometric errors, the roll error is the most difficult to measure. Currently, many methods are developed to measure the roll error [1][2][3][4][5][6][7].One of the most researched methods is based on optical heterodyne phase detection with wave plate and polarizer [1]. This method is then improved to achieve higher sensitivity [2][3][4] by using a transverse Zeeman laser as the light source, a quarter wave plate to produce elliptically-polarized light and a polarizer or a half wave plate adopted as a sensor.…”

“…The sensitivity on the order of an arcsecond(0.3″) at a certain angle was achieved in this method. Other measurement systems based on different detection means are presented [5][6][7][8], which are easy to set-up but have relatively low measurement accuracy.…”

A single-beam probe method for roll angle measurement

“…Optical measurement of a roll angular displacement has been applied for the precision machines and biosensors [1][2][3][4].…”

Fiber-optic angle sensor based on an extrinsic Fabry–Perot cavity

“…Wu and Chuang [9] adopted a wave-retardation plate as the roll-sensing element and a commonpath heterodyne interferometer as the measurement structure in order to measure angles with a resolution of sub-microradians over 0.5 • . Moreover, Li et al adopted a magnetic garnet single crystal to construct a roll-angle sensor with an angular resolution of 0.01 • in a range of ±30 • [10]. In summary, it is extremely difficult to construct an optical or electric angle sensor that can incorporate high resolution, compactness, and infinite range.…”