Patent ID: 8514406

Claim:
A measurement apparatus which measures a surface shape of a measurement target surface, the apparatus comprising: an optical system configured to split light from a light source into measurement light and reference light, guide the measurement light onto the measurement target surface, and guide the reference light onto a reference surface; a detection unit configured to detect an intensity of the measurement light reflected by the measurement target surface, an intensity of the reference light reflected by the reference surface, and an interference pattern formed between the measurement light reflected by the measurement target surface and the reference light reflected by the reference surface; and a processing unit configured to obtain a surface shape of the measurement target surface based on an interference signal of the interference pattern detected by said detection unit, wherein said processing unit obtains the surface shape of the measurement target surface based on the intensities of the measurement light and the reference light detected by said detection unit and the interference signal of the interference pattern detected by said detection unit, wherein said processing unit controls a position of at least one of the measurement target surface or the reference surface so that a region where only the measurement light enters, a region where only the reference light enters, and a region where both the measurement light and the reference light enter is present on said detection unit, and wherein said detection unit detects the intensity of the measurement light in the region where only the measurement light enters, detects the intensity of the reference light in the region where only the reference light enters, and detects the interference pattern in the region where both the measurement light and the reference light enter.