| 摘要 |
<p>PROBLEM TO BE SOLVED: To hold a high inspection light intensity even in the case of a short wavelength with a fixed value or less for use over a long time, by inserting a non-linear optical element for converting incidence light into a beam with a wavelength shorter than its wavelength, between a polarization means and a sample. SOLUTION: The second harmonics (532 nm) of a Q switch YAG laser 1 with a repetition frequency of 100 MHz are applied to an AO modulator 2 for scanning in Y-axis direction. Then, after a laser beam is focused in X direction that is vertical to a paper surface by an AO modulator 3, it is applied to aβ-barium borate 4 that is a non-linear optical crystal to generate fourth harmonics (266 nm). Then, only the fourth harmonics are transmitted through a BPF 5, are applied to a mask 8 through a 2-beam branching mechanism 6 and an objective lens 7, and is focused by a collector lens 9, and a transmission light intensity is observed by photo detectors 10 and 11, thus retaining the transmittance of a diffraction medium for constituting the AO modulators 2 and 3 at a high value, hence preventing inspection light intensity from decreasing, and preventing the AO element from deteriorating even after a long-term use.</p> |
