Measuring roll angle displacement based on ellipticity with high resolution and large range

• A novel method to measure the small roll angular displacement is proposed.
• The system is compact and it is convenient to be installed in practice.
• A 2.16′′ step roll angle displacement has been recognized.

A novel and compact roll angle displacement measurement based on the principle of the light׳s polarization is presented. The ellipticity of the light has been chosen as the final output, which shows a good linear relationship with, and a high sensitivity to, the roll angle displacement. In the experiments, a 2.16′′ step roll angle displacement has been recognized by this novel system and the linear range can be extended to 15°. The major components of this system are just a half-wave plate, a quarter-wave plate, a commonly used semiconductor laser, and a detector. Therefore, it is very easy to construct such a system both in the laboratory environment and the actual measurement environment.