Vacuum measurement using total-internal-reflection heterodyne interferometry

Based on the effect that the phase difference between s- and p-polarization s at the total-internal-reflection is changed with the variation of the air refractive index, which is related to the air pressure, a new optical meth od for measuring the air pressure of a vacuum cavity is proposed. From the experimental curve of the phase difference variation measured by the hetero dyne interferometry and the calibrated pressure measurement of a vacuum cav ity, an empirical formula is derived. With this empirical formula, the mens urable range of this new optical method is 760 to 0.1 torr. (C) 1999 Elsevi er Science Inc. All rights reserved.