PRECISE-TWIST MEASUREMENT BY LASER-HOLOGRAPHIC INTERFEROMETRY

• Published in: Experimental techniques (Westport, Conn.) Vol. 11; no. 6; pp. 26 - 27
• Main Authors: Rao, C. B., Venkatraman, B., Shyamsunder, M. T., Raj, B., Bhattacharya, D. K.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-06-1987
• ISSN: 0732-8818; 1747-1567
• DOI: 10.1111/j.1747-1567.1987.tb00419.x

The use of interferometric fringe density, derived by double-exposure holography, to measure changes in the tilt of an object is studied. The tilts of a precision mirror tilter were measured using the optical-lever method and double-exposure holograms. The fringe densities and angles of tilt are examined and compared; good correlation between the values is obtained. It is noted that the laser-holographic method is effective for measuring tilts because it is a noncontact method, it uses advanced methods of fringe counting, and tilt can be measured at any point; however, it does not provide direction of tilt and for tilts greater than 120 sec the fringe density is too large for resolution. (I.F.)