Surface gauging by remote image tracking

Claim 1

Apparatus for gauging the surface contour of a test specimen comprising: means for providing an incident beam of radiation; means for modulating the intensity of the beam; means for concentrating the beam and directing the concentrated beam along an incident axis to a spot on the surface of the specimen; detection means for the production of electronic signals in response to the radiation incident thereon, the detection means being positioned along a collecting axis and having a surface comprising a plurality of discrete zones with a null position between adjacent zones; means for collecting radiation reflected by the specimen and diverting the collected radiation along the collecting axis to form an imaged spot on the detection means surface; means responsive to the electronic signals for locating the particular zone of the detection means upon which the imaged is incident and for providing a corresponding position signal; means responsive to the position signal for causing relative motion between the specimen and the detection means to drive the imaged spot across the surface zone through the null position; means responsive to the passing of the imaged spot through a null position for providing null signals; and means responsive to the null signals for indicating the displacement of the imaged spot with respect to the detector between successive null signals.

Claim 7

The method of gauging the surface of a test specimen including the steps of: providing an incident beam of radiation; modulating the intensity of the beam at a preselected frequency; concentrating the beam along an incident axis to a spot on the surface of the specimen; collecting radiation reflected at the spot on the specimen along a collecting axis; providing a flat radiation sensitive surface along the collecting axis and perpendicular thereto; forming an image of the spot on the radiation sensitive surface; scanning the spot across the surface of the specimen in a succession of incremental movements; moving the detector with respect to the specimen between each incremental movement whereby the imaged spot is passed through a prescribed reference on the surface of the detector; measuring the displacement of the detector surface in the plane perpendicular to the collecting axis required to cause the imaged spot to pass through a reference; and correlating the measured displacement of the detector surface with the corresponding variation in the surface of the specimen.

Claim 8

The method of gauging the surface of a test specimen including the steps of: providing an incident beam of radiation; modulating the intensity of the beam at a preselected frequency; concentrating the beam along an incident axis to a spot on the surface of the specimen; collecting radiation reflected at the spot on the specimen along a collecting axis; providing a flat radiation sensitive surface along the collecting axis and perpendicular thereto; forming an image of the spot on the radiation sensitive surface; scanning the spot across the surface of the specimen in a succession of incremental movements; moving the detector with respect to the specimen between each incremental movement whereby the imaged spot is passed through a prescribed reference on the surface of the detector; measuring the displacement of the detector surface in the plane perpendicular to the collecting axis required to cause the imaged spot to pass through a reference; and correlating the measured displacement of the detector surface with the corresponding variation in the surface of the specimen.