Patent ID: 7787133

Claim:
An optical displacement-detecting mechanism, comprising: a light source for irradiating a target for measurement with light; a light source-driving circuit for driving the light source; an optical detector for receiving light after the irradiation of the target for measurement by the light source and converting the light into an electric signal thereby to detect an intensity of light; a current-voltage conversion circuit for processing a detection signal of the optical detector with a predetermined amplification factor, wherein when intensity spectra of the light source are measured with respect to a wavelength, a half width of the spectrum having a maximum intensity is not less than 10 nm, and the light source is driven with an output power of not less than 2 mW; and an optical member with a reflecting surface of an arbitrary reflectance having a polarization dependence on an optical path from the light source through the target for measurement to the optical detector, wherein the light source has polarization dependence, and the light source and optical member are disposed so that the reflectance of the optical member becomes higher.