| 摘要 |
PURPOSE:To obtain a light interference body which has excellent resolving power and permits easy decision of polarities by providing a projection surface having >=1 steps to the light interference body. CONSTITUTION:A laser 12 projects the light interference body 10 to cast reflected light to a photodetector 13. An arithmetic part 14 counts the peaks generated in the reflection intensity R of the reflected light and computes temp. in accordance with the number of the peaks. The projection surface 10A is formed of a projection part 10a and a projection part 10b having a step therefrom. Reflection increasing films 11 are provided on the projection surface 10A and the opposite surface 10B so that the light is effectively reflected. Then, the peaks Pa, Pb corresponding respectively to the projection parts 10a, 10b can be generated with a phase difference of about pi in the reflection intensity R when the reflectivity and the thickness of the light interference body 10 fluctuate by heating said body. Said peaks indicate that the resolving power of the light interference body 10 is doubled. The resolving power is tripled if the projection 10A is similarly formed of the three projection parts having the two steps. The polarities of a temp. change can be decided when the ratio of the light intensities of the peaks Pa, Pb is changed.
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