| 摘要 |
PURPOSE:To accurately measure the depth of a fine groove, by irradiating a specimen having a fine groove formed thereto with light from the groove depth direction and measuring the wavelengths of rays of light corresponding to a plurality of extreme values of the distribution of spectral intensity other than the zero-dimensional diffraction light while changing the wavelength of irradiated light. CONSTITUTION:Light is allowed to irradiate an object to be measured and the diffraction lattice 33 of a spectral part 37 is rotated to continuously change the wavelength of irradiated light in a range of 300-800nm. At this time, a mirror 38 is rotated in matching relation to a wavelength lambda according to formula (wherein theta is the diffraction angle of diffraction light, lambda is a wavelength, lambda is the pitch of the diffraction lattice and am is a predetermined value and 3 when tertiary diffraction light is taken in). As mentioned above, zero-dimensional and n-dimensional (three-dimensional) rays of diffraction light are respectively detected by light detectors 41, 42 while the diffraction lattice 33 and the mirror 38 are rotated and the take-in light is subjected to photoelectric conversion by a light detector, amplified to be subjected to A/D conversion and processed by a calculator. |
