Importance

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Abstract

An instrument for measuring the topography of a surface, comprising a light transmitting device for transmitting a light beam onto the surface; a light receiving device for receiving light reflected by the surface; a detector for detecting the position of the received light relative to the optical axis of the light receiving device; and means for providing relative movement between on one hand the light transmitting (10,L1,L2) and light receiving (L3,L4,8) devices, and on the other hand the surface (2) to be measured. According to the invention the optical axis (11) of the light transmitting device (10,L1,L2) is arranged to form a small angle (.gamma..sub.1) with the normal to the median plane (13) of a workpiece surface (2) to be measured. The angle (.gamma..sub.1) is smaller than about 15.degree.. The optical axis (9) of the light receiving device (L3,L4) forms a right angle, or substantially a right angle (8) with the optical axis of the light transmitting device. The detector (8) is position-responsive, and an image magnifying lens (14) is located in front of the detector.

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First Claim