OPTICALLY MEASURING APPARATUS

PROBLEM TO BE SOLVED: To increase the measuring area for one visual field and to decrease the number of times of measurements of the surface to be measured by arraying each effective visual field in a zigzag state in a manner that a part thereof is overlapped, and sequentially measuring the entire surface of the surface to be measured. SOLUTION: When alignment of the effective visual fields C is observed in a longitudinal direction, the fields are linearly aligned, but when the alignment is observed in a lateral direction, they are disposed in a regularly zigzag state and the fields C are disposed so that cutout parts and circular arc-like parts are superposed by the same size in the adjacent visual fields C at both sides of the lateral direction. The entire surface to be measured is sequentially measured in the state that the respective fields are partly overlapped. The utility ration of the optically effective circular measurable visual fields is actually largely improved. Accordingly, the measuring area of one visual field is increased to cause the decrease in the number of the fields of the surface to be measured, i.e., the decrease in the number of times of the measurements to improve the measuring throughput.