Patent ID: 6916225

Claim:
A monitoring device which is equipped with a polishing body part that has a rotatable polishing body with a working surface, and a substrate holding part that holds a substrate, and which monitors the polishing conditions by means of a reflected signal light obtained by illuminating the polished surface of the substrate with probe light when the polished surface is polished by interposing a polishing agent between the rotating working surface and the polished surface, and producing a relative motion between these two parts, the monitoring device being characterized by the fact that the device is equipped with a non-rotating light source which emits the probe light, a non-rotating light detector which receives the reflected signal light, and a turnabout optical part which emits the reflected signal light from a specified position on the axis of rotation of the polishing body part when the probe light is incident on this specified position, and which is incorporated into the polishing body part, so that the optical part can rotate together with the polishing body, wherein the turnabout optical part is equipped with a light-coupling lens and a second optical fiber with a refractive index of n 0 , and the monitoring device is further equipped with a non-rotating first optical fiber.