A Ring Laser Gyroscope (RLG) consists of a ring laser having two independent counter-propagating resonant modes over the same path, it is an optical gyroscope that utilizes narrowband light waveforms traveling a path, created using mirrors, to measure rotation based on the Sagnac effect. 

To be competent for integration into the Ring Laser Gyroscope (RLG), the mirrors and outcoupling coatings must have ultra-low absorption and scattering loss, exceptional resistance to the plasma environment, and long durability.

Shanghai North Optics offers the mirrors or substrates used in the laser gyro with a roughness of less than 1Å, by our classical super polishing line, atom force roughness measuring system, and Zygo interference flatness test instrument, we can provide the laser gyro mirrors in stable and identical quality and volume quantity.

Features:

1. Unique classical polishing method

Although the magnetorheological fluid polishing method is thought to be a promising measure to fabricate ultra-low roughness optical surfaces, its high cost and low production rate make it unpractical in industrial applications, therefore most of the super-polished optics are made from the classical polishing method. A unique processing technique modified based on classical polishing is developed in North Optics to make the super-polished optics, the pitch plate is used as the polishing tool, and <1Å roughness can be obtained using our polishing craft. The testing shows that our substrates and mirrors work well in the laser gyro system. 

2. Roughness measurement

For the primary scattering test, we use the green laser of 25 and 40 mW, the scattering point can be found by watching the reflected laser light from the surfaces of the optics, this is simple and fast as the primary test of surface roughness. For the final test of the roughness or scattering test, the Atom Force Microscope (AFM) from Bruker is used to measure the final roughness of the polished optics. Please see the following picture from the AFM measuring system.

3. Flatness Measuring

The Zygo Lambda 2000 series Module GPIXP-D6” is utilized to measure the final flatness of the polished surfaces. Please see the following diagram of the measurement.

4. Coating Testing

The final processing of coating is also critical for the laser gyro mirrors, low absorption and low scattering loss are required, and the Total Integrated Scattering or TIS is measured to evaluate the surface loss of the mirrors.