PURPOSE: To improve operability, responsibility and further, measuring accuracy of the titled gage by oscillating a diaphragm forcedly and detecting the amplitude optically and detecting a vacuum degree.
CONSTITUTION: The periodical electrostatic force acts upon between an electrode 4 provided to an insulating base 3 below a reflecting plate 2 and the reflecting plate 2 via an exciting power source 5 for generating the alternating voltage and a switching circuit 6. The reflecting plate 2 oscillates with a fulcrum 7 as a center as shown with a broken line 17 in figure by the periodical electrostatic force. When rays of light 11 are made incident on the reflecting plate 2 from a light source 9, the reflected light 12 is condensed on an array photosensor 10 by an angle α of polarization as shown with the broken line in figure in a accordance with an inclination of the reflecting plate 2. An output signal of the array photosensor 10 is amplified by an amplifier 13 and converted into the angle α of polarization by a control and arithmetic circuit 14. The amplitude by an oscillation of the reflecting plate is strongly influenced by the vacuum degree of an atmosphere. Consequently, the vacuum degree can be detected as a change of the angle α of polarization.
SATO KAZUO
TERASAWA TSUNEO
TANAKA SHINJI
