Three-dimensional shape measurement system

A three-dimensional shape measurement system for producing three-dimensional information of an object under examination, the system comprising:

• a laser beam source for producing a laser beam;
• scanning means for two-dimensionally scanning the object with the laser beam in two scanning directions;
• an optical system for directing the laser beam along an optical axis onto the object so that the laser beam is reflected by the object as reflected light;
• laser beam control means for focal point shifting in the direction of the optical axis of the optical system which intersects the scanning directions of the scanning means;
• detection means for detecting a variation in focal position of the light reflected from the object and deriving, from the detected variation, information regarding shape properties of the object in a direction of the optical axis of the optical system and producing output signals representative of the shape properties of the object;
• first signal processing means for processing output signals of the detection means to eliminate the effect of optical reflectance properties of the object;
• and
• second signal processing means for processing the output signals of the detection means to discriminate a condition of the focal position with respect to the object established by the laser beam control means so as to drive the laser beam control means to produce a focused condition.