Optical micrometers use a “shadow” measurement principle whereby collimated laser light is transmitted towards a receiver. The edges of the shadow cast by an object in the beam’s path are accurately measured by the detector array inside the receiver unit. Optical Micrometers are non-contact devices that ideally measure diameters of wires, rods and other cylinders in addition to gaps, edge positions and dimensional characteristics of geometric objects.
The micrometer operation is based on the so-called ‘shadow’ principle. The micrometer consists of two blocks – transmitter, 1 and receiver, 2. Radiation of a semiconductor laser 3 is collimated by a lens 4. With an object, 5 placed in the collimated beam region, shadow image formed is scanned with a CCD photo-detector array 6. A processor 7 calculates the position (size) of the object from the position of shadow border (s).