PURPOSE: To reduce the size reduction and to improve the precision by providing light emitting elements and photodetecting elements while the 1st and the 2nd light shield plates arranged oppositely to each other are interposed, and counting pulses which are obtained by each photodetecting element when the 1st light shield plate is oscillated and detecting the amplitude.
CONSTITUTION: While the 1st and the 2nd light shield plates 1 and 2 facing each other are interposed, (n) units of light emitting elements 3 and photodetecting elements 4 are juxtaposed. The 1st light shield plate 1 has numbers of slits 5 at pitch P, and the 2nd light shield plate 2h has (n) slits 6 at pitch S; and optical axes l connecting the respective light emitting elements 3 and photodetecting elements 4 run through the respective slits 6 of the 2nd light shield plate 2. The pitches P and S of both light shield plates 1 and 2 are set to satisfy an equation, and pulses obtained by the photodetecting elements 4 when the 1st light shield plate 1 is oscillated as shown by (a) are counted for a specific time to detect the amplitude of the oscillating body.
TSUCHIKAWA HIROYUKI
HIGASHIMURA YOUJI
SATOU HIDEO
TANIMURA YOSHIHIKO
