| 摘要 |
PROBLEM TO BE SOLVED: To use all the wavelengths of the diffracted beams of a desired order, when using diffraction. SOLUTION: A height detector includes a height-detecting means 120, having an optic fiber 121 for regulating passage of beam other than the beam forming a focus in the vicinity of a surface of a workpiece 1 among reflected beams; a diffraction optic element 122 for splitting the reflected beam which has passed through the optic fiber 121 into diffraction beam spreading in the same plane; and a primary diffraction beam detecting means 130 for detecting only the primary diffracted beam among the primary diffracted beam and higher-order diffracted beams contained in the diffraction beam. The primary diffracted beam detecting means 130 includes a diffracted beam condenser lens 131 for condensing the diffracted beam; a wavelength dispersion filter 132 for refracting the condensed diffracted beam, in a direction of going out of the same plane, at different angles for each of wavelengths; a wavelength detection sensor 133, having a detecting part only at a portion where the primary diffraction beam is condensed so as to detect the beam intensity of each wavelength of only the primary diffracted beam; and a memory 134 for storing a control map in which focus distances of the respective wavelengths of white beam condensed by a chromatic aberration lens 102 are stored. COPYRIGHT: (C)2011,JPO&INPIT |
