The GR1 Gas Laser Refractometer is a high accuracy optical interferometer which counts the number of fringes that are created by the change in optical path length through the sample cell as the refractive index of the gas within it changes.
The GR1 has its own special counting unit (ICF 1/1000) to carry out this exacting task. The unit displays and outputs the results in terms of fringe count, refractive index (RI) or, if the appropriate scaling factors are entered, gas concentration.
At the heart of the GR1 lies a special type of self-compensating Jamin interferometer. This ensures that besides being an extremely sensitive instrument, it is also ultra-stable. The GR1 incorporates a patented operating system, developed by the UK National Physical Laboratory (NPL) and manufactured by Index Instruments under licence from the British Technology Group (BTG). The entire system is engineered into a high quality, robust, main frame, designed to withstand the rigours of an industrial environment. It is therefore equally at home in both a research and manufacturing quality control situation.