光位相変調と二次元ロックインアンプを用いた高感度複屈折分布測定装置の開発 [in Japanese] Measurement of birefringence distribution using optical-phase modulation and a two-dimensional lock-in amplifier system [in Japanese]
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The photoelastic fringe pattern measurement technique is a nondestmctive method and is widely used to measure the mechanical-stress distribution inside solid materials. This distribution is evaluated by generating a photoelastic fringe pattern and counting the number of isocbromatic fringes (dark lines). If the amount of the mechanical-stress is very small, however, and the corresponding birefringence is smaller than π radians, no fringe lines are produced. This method is therefore not suitable when the amount of the mechanical stress is small. Furthermore, if 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 π radians by using an electro-optical phase modulator (Pockets cell) and a two-dimensional lock-in amplifier system. This system can also at the same time measure the azimuth angle without rotating the sample. Here we report the principle of this two-dimensional measurement system and give the results of measuring the 2-D bireffingence distribution in a glass plate.
- The Journal of the Institute of Electrical Engineers of Japan
The Journal of the Institute of Electrical Engineers of Japan 117(12), 581-587, 1997-12-01
The Institute of Electrical Engineers of Japan