An accurate interference refractometer based on a permanent vacuum chamber : development and results

A new accurate interference refractometer, without pumping device, has been developed. The refractometer is based on a commercially available laser measurement system and uses a prismatic measuring cell, containing a permanent vacuum chamber. Measurements of the refractive index of air can be carried out accurately, easily and quickly with this instrument. For this instrument also a new arrangement of a double pass, plane mirror interferometer with high stability was developed. The accuracy of the interference refractometer is analytically and experimentally determined and appeared to be better as 1 part in 107