At this moment, the sample 1 passes through the clearance between the two carrying conveyers 111 and 112 at a certain carrying speed. [0120] The linear light source 32 is then set at the light irradiation angle ??1, which is deflected from the light irradiation angle ??0 by a predetermined angle, to pick up an image other than the regular reflection (e.g., scattered light) on the rear surface of t