A new method of angle measurement based on the internal reflection
effect is proposed that uses a single right-angle prism. We measure
the angular displacement between a laser beam and the prism by
detecting the changes in reflectance as a function of the angle of
incidence. We achieve high linearity of measurement by taking the
inverse of reflectance as the output. The inverse of reflectance is
obtained from the intensities of the reflected and the transmitted
beams measured by two photodiodes. Experiments with a prototype
device have demonstrated that angle measurement with a range of ±500
arc sec, a nonlinearity error of ±0.1%, and a resolution of 0.1 arc
sec can be readily achieved. The measurement range can be further
increased with some sacrifice of linearity.
© 1998 Optical Society of America
Equations on this page are rendered with MathJax. Learn more.