[OPTICAL REVIEW Vol. 1, No. 2 (1994) 276-277]

Dynamic Photoelastic Analysis by Optical Heterodyne Polarimetry

Tomoko YAMAGUCHI, Kazuhiko OKA and Yoshihiro OHTSUKA

Department of Engineering Science, Faculty of Engineering, Hokkaido University, N13W8, Kita-ku, Sapporo, 060 Japan

(Accepted September 29, 1994)

This paper describes the mapping of the spatiotemporal principal stress distribution evolved with time in an epoxy photoelastic sample. In the optical heterodyne polarimeter exploited, the signal beam of light transmitted by the sample under continuously loaded condition is photomixed with the local oscillator beam of light made up of orthogonal linearly polarized two-frequency components. Every pixel of a MOS video camera used generates a beat photocurrent that possesses the two orthogonal field components of the elliptically polarized signal beam. The spatiotemporal principal stress distributions can be uniquely determined simultaneously and independently from these two orthogonal field components, and are successfully mapped in a time-sequential form. The spatial and temporal resolutions in the maps are 0.18 mm and 2.9 ms, respectively.

Key words : spatiotemporal photoelastic analysis, independent determinations of principal stresses, stress distribution mapping