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AssigneeU.S. Philips Corporation
InventorsJoseph L. Horijon, Christiaan H. F. Velzel, Cornelis S. Kooijman
Estimating the term…
The height of a surface (25) along an axis (4) is determined by measuring the axial position of an irradiated spot (31) formed on the surface at the intersection of the surface and the axis. Radiation reflected by the surface and collected by a lens (8) forms an image spot (32) on the axis (4). The position of the image spot is determined by measuring the intensity of the radiation at at least three positions along the axis by means of a detection unit (35). The output signals (44, 44') of the detection unit are processed in an electronic means (43) for determining the position of the highest radiation intensity and for supplying a signal (43') whose magnitude represents the axial position of the image spot (32), hence, of the irradiated spot (31 ).
A device for optically measuring the height of a surface of an object, which device comprises a radiation source for generating an irradiating beam which is directed along a predetermined beam axis and forms an irradiated spot on the surface, and an imaging system for converging radiation reflected from the irradiated spot to a radiation beam forming an image spot on the predetermined beam axis in the image space of the image system, characterized by a detection unit arranged in the image space for receiving radiation from the radiation beam at at least three different positions along the predetermined beam axis and for converting said radiation into electric signals and by electronic means for determining, from said signals, that position of the at least three positions which receives the maximum amount of radiation, said position being related to the height of the surface at the location of the irradiated spot.
Dependencies are inferred from the claim text.