| 摘要 |
PROBLEM TO BE SOLVED: To inspect the height of a fine protrusion at a high accuracy and a high speed. SOLUTION: Projection optical system means radiates a light beam so as to locate the surface of a sample under test at a focused position and deflects a beam spot formed on the sample surface to linearly reciprocally scan over an inspecting region at a specified period. Detecting optical system means generates two semi-circular light beams with mutually different regions shielded from light beams reflected from the sample surface, and they are received separately by a first and second optical sensor means to obtain height information from detected signals thereof. Thus the height information are obtained, based on the detected signals from the two systems of optical sensor means, hence the detection accuracy is improved and, if a thermal variation of each optical element constituting the projection optical system means or a deflection error in the deflection causes a spot scan deviation (Δt), a high accuracy measurement can be made, without being influenced thereby.
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