Method for inspecting object defection by light beam

摘要

A narrow beam from a laser source-like light beam is projected on an object, the light scattered from the projected spot of the object is detected by light detecters at a plural number of the detecting positions. The distribution of the scattered light is detected by comparing the values of the densities of the scattered lights at the plural number of the detecting positions among each other in such a manner that it is determined from the distribution of the scattered light whether there is a defect on the projected spot or not.