摘要 |
A non-contacting revolving speed detecting apparatus for detecting the speed of rotation of a rotary body includes a diffraction plate that may be attached to the surface of the rotary body, a light source for radiating monochromatic laser light onto the diffraction plate, a light detector for detecting an output diffraction pattern of reflected and diffracted light from the diffraction plate, and circuitry for processing an output signal from the light detector means to detect and display the speed of rotation of the rotary body in either a digital or an analog manner.
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