Gyroscope base plate

The Laser gyro is mounted on a base plate, which can be rotated precisely by a rotation stage with high precision. The axis of rotation is present in the centre of an equilateral triangle. The laser radiation produced traverses the perimeter of this triangle. The Helium Neon laser tube is closed on both the sides by a Brewster window and thus causes the linear polarization of the laser beam. In order to force the laser in single mode, a quartz etalon plate with a thickness of 10 mm is placed inside the resonator is used. The laser resonator consists of three mirrors M1, M2 and M3. The mirrors M1 and M2 are plane mirrors, and the mirror M3 is a spherical mirror with a radius of curvature of 1000 mm.