Real-time measurement of two-dimensional birefringence

Keigo Itoh; Teruhisa Okhawa; Yongchang Zhu; Tatsuo Takada; Takashi Maeno

doi:10.1117/12.246252

16 August 1996 Real-time measurement of two-dimensional birefringence

Keigo Itoh, Teruhisa Okhawa, Yongchang Zhu, Tatsuo Takada, Takashi Maeno

Proceedings Volume 2873, International Symposium on Polarization Analysis and Applications to Device Technology; (1996) https://doi.org/10.1117/12.246252
Event: International Symposium on Polarization Analysis and Applications to Device Technology, 1996, Yokohama, Japan

Abstract

The photo-elastic fringe pattern measurement technique is a nondestructive method widely used to measure the mechanical stress distribution inside solid materials. The mechanical stress distribution is evaluated by generating the photo-elastic fringe pattern and counting the number of isochromatic fringes (dark lines). If the amount of the mechanical stress is very small, however, and the corresponding birefringence is smaller than t radians, no fringe lines are produced. This method is, therefore, not suitable when the amount of the mechanical stress is small. Furthermore, ii the azimuth angle of the mechanical stress is to be measured, the sample needs to be rotated. We therefore developed a highly sensitive measurement system suitable for measuring birefringence distributions smaller than 7r radians by using an electro-optical phase modulator (Pockels cell) and a two-dimensional lock-in amplifier.1 This system can also measure the azimuth angle simultaneously without rotating the sample. Here we report the principle of this two-dimensional measurement system and give the results of measuring the 2-D birefringence distribution in PMMA fixed beam.

Citation Download Citation

Keigo Itoh, Teruhisa Okhawa, Yongchang Zhu, Tatsuo Takada, and Takashi Maeno "Real-time measurement of two-dimensional birefringence", Proc. SPIE 2873, International Symposium on Polarization Analysis and Applications to Device Technology, (16 August 1996); https://doi.org/10.1117/12.246252

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