Basic investigations on an angle measurement system using a laser

A novel, precise angle gauge is proposed. Incoming laser light is fed to the system through two separate condensing lenses. The phase difference between two rays is compensated by a phase modulator to hold a constant interference condition. The angle of the incoming light is measured by the modulation voltage. In comparison with conventional angle gauges, its advantages are high measurement accuracy, simple structure, and compatibility to feedback control systems. Because of these advantages, the angle gauge is suitable for navigation using angular information. Some examples of possible applications are provided. The experimental system was formed to be compatible with practical conditions and performance were verified experimentally. It is shown that an angle resolution less than 1×10^-7 rd can be expected