| 摘要 |
PROBLEM TO BE SOLVED: To provide a simple and highly sensitive method for measuring the incident angle of light beam and an apparatus requiring a small space. SOLUTION: The differential measuring method for the incident angle of light beam produce a series of interference fringes by passing a polarized light beam 10 through a birefrigence plate 12 following to a polarization analyzer 11 twice and analyzes the orientation and interval of the top of fringes, which are direct functions of measuring angleγ, by means of an appropriate detector 15 and an electronic analyzing circuit. The measuring apparatus comprises a single polarization analyzer 11, a birefrigence plate 12 followed by a reflector 13 and passing a light beam 10 twice, and an apparatus 15 for detecting variation of luminous intensity including an electronic analyzing circuit. By passing the light beam twice through the birefrigence plate, an optical element is adjusted in one place V to optimize the efficiency and sensitivity and to optimize the measurement other plane H thus realizing a simple vibration measuring apparatus sensitive to angular displacement, for example.
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