Optical detection of flaws in object e.g. optical data carrier such as compact disc, by altering characteristic of light that is reflected or transmitted along non-standard axis

摘要

The object is illuminated by a light source (12) and the reflected or transmitted light (15) is received by a light-sensitive receiver (13). If the object is perfect, the light is reflected or transmitted along a standard emergent axis at a standard emergent angle. Before reception, at least one characteristic of at least part of the incident light is altered, if the light is reflected or transmitted along an axis or at an angle that deviates from the standard. The intensity and/or polarization of the light may be altered, and/or at least one wavelength or wavelength range may be filtered. An independent claim is included for an apparatus for detecting flaws in an object.