| 摘要 |
PURPOSE:To remove completely variation in the spatial quantity of light without requiring any movable part to scan an optical path difference by obtaining an interference figure signal on the basis of a signal detected before one polarizer rotates and a detection signal after a 90 deg. turn. CONSTITUTION:While a polarizing plate 35 is inserted into an optical path, a photodiode array 50 is scanned electronically with a driving signal 56 from a clock generation source 55 and a video signal 59 which is read out successively is amplified 60, and sampled and held; and the held signal is A/D-converted 70 into a digital value 79, which is stored in a memory 85 in order. Then, an axis 36 of polarization is rotated by 90 deg. to an axis 46 of polarization by the movement 31 of a polarizing plate slider 30 and the video signal 59 of interference fringes 52 is obtained as a digital value 70' through amplification 60 and A/D conversion 70 as mentioned above and inputted to a subtracter 90 and stored data 89 is read out at the same time in synchronism with the clock generation source 55 and inputted to the other input of the subtracter 90. The difference signal, therefore, appears at the output 95 of the subtracter 90 and an accurate interference figure is obtained. Thus, the reliability of the device is improved.
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