| 摘要 |
PURPOSE:To manufacture the optical filter simply and accurately by using various optical filters according to the kinds of defects, detecting fine changes in defects by means of electric signals and thereby manufacturing the filter having the least common multiple properties. CONSTITUTION:Several kinds of optical band-pass filters 4 are arranged in replacement with one another successively on a diffraction pattern image, and base on the output signals of a photoelectric transducer 5 according to a defective sample 1 obtained when respective optical band-pass filters are applied, S/N values are recorded on a recorder 6. Then, based on the data thus recorded, a place where the S/N value is the maximum, i.e. an optimum filter zone is selected, and thus the reference filter which makes it possible to catch various defects in an averaged manner is obtained. |
