Polishing apparatus and polishing pad

摘要

A polishing pad ( 10 ) has an upper-layer pad ( 11 ) having a hole ( 11 a) defined therein, a light-transmittable window ( 41 ) disposed in the hole ( 11 a) for allowing light to pass therethrough, and a lower-layer pad ( 12 ) disposed below the upper-layer pad ( 11 ) and having a light passage hole ( 12 a) defined therein which has substantially the same diameter as the hole ( 11 a) in the upper-layer pad ( 11 ). A transparent film ( 13 ) with an adhesive agent applied to upper and lower surfaces thereof is interposed between the upper-layer pad ( 11 ) and the lower-layer pad ( 12 ). The hole ( 11 a) defined in the upper-layer pad ( 11 ) and the light passage hole ( 12 a) defined in the lower-layer pad ( 12 ) have substantially the same size as each other.