US 5,309,222 AGranted

Surface undulation inspection apparatus

AssigneeMitsubishi Denki Kabushiki Kaisha

InventorsMitsuhito Kamei, Mikio Tachibana

Life of this patent

Estimating the term…

Loading patent…

Abstract

A surface undulation inspection apparatus for detecting a defect of a fine undulation including a change of a gentle profile or the like on a suitable surface of a specimen to be inspected, wherein a patterning light source is opposed to an image pickup lens having a pin hole with a specimen interposed therebetween to pin-hole image pickup the patterning light source through the specimen to be inspected whereby a ray passing through the specimen to be inspected is specified as a principal ray, and a local surface undulation defect on the surface of the specimen is stressed and a defective part is specified. Further, a display pattern generated by a pattern generator is displayed on a pattern display element to used it as a patterning light source, the pattern generator is feedback controlled by a deviation calculation circuit, a standard data generator circuit, a pattern width coincidence decision circuit and a comparison data circuit, or a coordinate conversion circuit and an angle detector circuit, and an intensity of the display pattern is regularly changed in an analog manner to detect an abnormality on the basis of a differential from the image data.

Claims6

Dependent claims

A surface undulation inspection apparatus in which a patterning light source and a camera are arranged on opposite sides with respect to a specimen to be inspected, said camera selectively focussing only a principal ray adjusted in focal point to said patterning light source through said specimen to be inspected, said apparatus comprising:

a pattern display element used as a patterning light source,
a pattern generator operatively connected to said pattern display element for generating a display pattern displayed on said pattern display element,
a driver connected between said pattern generator and said pattern display element for causing the display pattern generated by said pattern generator to be displayed onto said pattern display element,
a synchronous signal generator circuit connected to said driver and a camera for synchronizing said driver with scanning of the camera,
a deviation calculation circuit connected to the camera for counting the number of stripes of an image data taken from the camera and calculating a deviation from a reference stripe pattern width data, and
a standard data generator circuit connected to said deviation calculation circuit for producing said stripe pattern width data corresponding to a counted value of said number of stripes output from said deviation calculation circuit and to feed it back to said deviation calculation circuit,
said pattern generator having a function of generating a stripe-like display pattern and changing said display pattern generated so that a deviation output by said deviation calculation circuit is zero.

4 more elements

Dependencies are inferred from the claim text.