Title :
A new refractometer by combining a variable length vacuum cell and a double-pass Michelson interferometer
Author :
Fujii, Ken-ichi ; Williams, E.R. ; Steiner, R.L. ; Newell, D.B.
Author_Institution :
Nat. Res. Lab. of Metrol., Ibaraki, Japan
fDate :
4/1/1997 12:00:00 AM
Abstract :
A new refractometer with a variable length vacuum cell has been developed to eliminate errors caused by deformations in optical windows of the cell. The refractive index of air is determined by measuring the changes in the optical path difference between the air of interest and a vacuum as a function of the changes in the cell length. An optical phase modulation technique and a dark fringe detection method are used to obtain a high resolution in measuring the optical path difference by a double-pass Michelson interferometer. A combined standard uncertainty of 5×10-9 in the measurement of the refractive index of air has been achieved
Keywords :
Michelson interferometers; air; measurement errors; measurement standards; optical modulation; optical resolving power; optical windows; phase modulation; refractive index measurement; refractometers; vacuum apparatus; air; cell length; combined standard uncertainty; dark fringe detection method; deformations; double-pass Michelson interferometer; errors; high resolution; optical path difference; optical phase modulation technique; optical windows; refractive index; refractometer; variable length vacuum cell; Length measurement; Measurement standards; Optical interferometry; Optical modulation; Optical refraction; Optical variables control; Phase detection; Phase measurement; Phase modulation; Refractive index;
Journal_Title :
Instrumentation and Measurement, IEEE Transactions on
