| 摘要 |
PURPOSE:To make it possible to measure surface roughness up to an accuracy to the order of 0.1mum and below, by projecting a reduced image on an article to be measured through a mask having a predetermined perforated pattern and, thereafter, forming the reflected image thereof to a light receiving element in an enlarged state. CONSTITUTION:The light from a light source 11 passes through a mask to be reduced as a trapezoidal pattern image by a reducing optical system to be formed into an image on an article 30 to be measured such as an IC board. This reduced pattern image is enlarged by an enlarging optical system 40 to be formed on a light receiving system 41. A signal processing circuit 50 inputs the output signal of the light receiving element 41 to output a display signal to a display apparatus 60. In this case, if the surface roughness of the article 30 to be measured is zero, a trapezoidal contour is displayed on a display device 60 as a distorted straight line. By this method, even surface roughness to the order of 0.1mum and below can be accurately measured.
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