Development of new methods and means of dynamic laser goniometry

Precision Angle Measurement Systems on the Basis of Ring Laser Gyro

“…This also carries the risk of additional non-stationary temperature effects. Another approach is the method of dynamical angle measurements [6]. In this method the ring laser continuously rotates around the vertical axes together with an optical null-indicator (NI).…”

“…Therefore, the concept of a goniometer operating in a dynamic mode, based on a HeNe ring laser gyro, has progressively come into use. This concept has been developed and evaluated by the authors for a long time [6]. This effort was renewed by a recent project, where the Pisa university, together with the Italian Metrological Institute [7], built a special ring laser in order to obtain ultra-high resolution for angular measurements in the dynamic mode.…”

“…It allows the calibration of angular encoders with high precision at small angular intervals. The laser dynamic goniometer (LDG), which operates in an automated mode, is a logical extension of traditional goniometers designed to measure the angles between different faces of an optical polygon, the angular deflection of beams passing through transparent prisms and wedges, the determination of the refractive index and the dispersion of optical materials [6,8]. The LDG's method of the angle measurement is based on the physical principle of the operation of an active Sagnac interferometer, which supports two counter-propagating electromagnetic waves in a ring cavity, whose frequency offset results from the instantaneous rate of rotation.…”

“…The block diagram of the LDG is shown in Figure 1. It consists of a ring laser (1), a rotary platform (2), a drive (3), an angle converter consisting of a rotor (4) and a stator (5), an electronic unit (6) and a computer (7). As an angle converter, one can either use an angle encoder or an optical polygon with an optical null-indicator.…”