Surface flaw detecting method and apparatus

Abstract

A method for detecting flaws in a surface of an inspected object can moderate the requirements for inspection condition accuracy, particular for adjustment of spatial relationships among a laser unit, the surface and an laser detector unit. The method includes the step of transmitting a laser beam in a known configurationonto a specular surface of the inspected object, projecting the laser beam reflected by the surface onto a light-scattering screen and forming an image of the surface on the screen, and detecting the image of the surface in the known configuration in relation to a predetermined portion of the screen. An apparatus carrying out the method includes a sensor for detecting positional deviation of the image of the surface from a fixed monitored portion of the screen, a adjuster for adjusting the angle subtended by the axes of a transmitter of the laser slit beam and a flaw-detecting image sensor and an adjuster for adjusting the inclination of a plane defined by the axes of the transmitted and the flaw-detecting image sensor relative the surface, both adjusters operating in accordance with the output of the deviation detecting sensor.

Dependencies are inferred from the claim text.