Opto-electronic high precision contactless dimension measuring appts. - uses light source and photoreceiver with converging lenses and light diffuser

摘要

The optoelectronic device makes high precision dimensional measurements without material contact. The detecting head has a light source (11) and a photoreceiver (21). The light source which may be on electroluminescent diode has an associated converging lens (13) which focuses the light onto the surface under inspection at an angle of incidence i. A light diffuser (15) next to the lens strongly attenuates the spatial variation of light intensity in the direction of the surface and of the photoreceiver. The photoreceiver which may be a photodiode or a phototransistor has an associated convergent lens (23) situated in the conjugated image plane of the inspection surface and is symmetric with the light source w.r.t. the normal to the surface. A removable transparent plate (41) is used for calibration. The measurement of a distance w.r.t. the surface at a given point is deduced from the amplified variation of voltage delivered by the photoreceiver illuminated by the reflected image of the light diffuser from which the radiation presents a given spatial variation of light intensity.