Patent attributes
A thickness measuring apparatus for measuring the thickness of a workpiece held on a chuck table includes the followings: a light source configured to emit white light; an optical branching unit configured to branch, to a second optical path, reflected light applied from the light source to the workpiece held on the chuck table via a first optical path and reflected from the workpiece; a diffraction grating disposed in the second optical path; an image sensor configured to detect an optical intensity signal of light separated into each wavelength by the diffraction grating; and a thickness output unit configured to generate a spectral interference waveform on the basis of the optical intensity signal detected by the image sensor, determine the thickness on the basis of the spectral interference waveform, and output the thickness.
