LONG DISTANCE INTERFEROMETRIC MEASUREMENTS WITH REFRACTIVE INDEX CORRECTION BASED ON SPEED OF SOUND

Milena Astrua, Marco Pisani, Massimo Zucco

Abstract

At INRIM a novel absolute long distance interferometer has been developed for application in space missions. The interferometer has been successfully tested for long distance measurements in air. Main limitation of such measurements is the knowledge of refractive index of air which in turn is mainly affected by air temperature. A method to measure average air temperature based on the measure of the speed of sound has been developed and combined with the absolute interferometer achieving measurement uncertainties less than 1 ppm in open air up to a 78 m distances.

Keywords

long distance interferometry, refractive index of air, temperature measurement, synthetic wavelength

Download

IMEKO-TC14-2014-21.pdf

DOI

-

IMEKO TC

TC14 - Measurement of Geometrical Quantities

Back to the proceedings