Method and apparatus for optically measuring the thickness of an object being machined by interferometry

摘要

The method of optically measuring the thickness of the machined object (2) by interferometry is that the primary reflected radiation (R1) generated by the reflection of the incident radiation (I) at the outer surface (16) and the object A direct measurement process in which the spectrum of the interference result between the secondary reflected radiation (R2) generated by reflection at the discontinuous inner surface (17) is analyzed, and the thickness variation of the object being machined is And a preliminary step in which information about variations in the virtual thickness (D) defined and defined by the suggested reference surface (18) and the outer surface of the object is processed. The processing in the preliminary step is based on the spectrum of interference results between the primary reflected radiation and the reference reflected radiation (Rref) generated by reflection of the incident radiation at the reference plane that defines the length of the reference optical path. An apparatus implementing such a method for optical measurement includes an optical probe (6) for receiving and detecting primary reflected radiation, secondary reflected radiation and reference reflected radiation, and a spectroscopic for analyzing the spectrum of the interference result. (5)