Abstract: A defect detection system for inspecting objects such as reticles, photomasks, semiconductor wafers, flat panel displays and other patterned objects has two or more stages, whereby the object is examined separately for fine defects, by inspecting a binary level representation of the object, and for ultra fine defects, by inspecting a gray level representation of the object. The system also includes re-inspection apparatus for re-inspection of detected defects, thereby to reduce the false alarm rate, and for classifying the remaining defects by size, area and type.

Abstract: An inspection method including the steps of providing a patterned object to be inspected and compared with a reference, inspecting the patterned object and providing an output of information relating to the visual characteristics of the patterned object, comparing binary level information relating to the visual characteristics of the patterned object to binary level information relating to the visual characteristics of the reference, and comparing gray level information relating to the visual characteristics of the patterned object to gray level information relating to the visual characteristics of the reference.

Abstract: The present invention seeks to provide an improved system for inspection of and detection of defects in objects such as reticles, photomasks, semiconductor wafers, flat panel displays and other patterned objects. Preferably, the system has two or more stages, whereby the object is examined separately for fine defects, preferably by inspecting a binary level representation of the object, and for ultra fine defects, preferably by inspecting a gray level representation of the object. The system also preferably includes reinspection apparatus for reinspection of detected defects, thereby to reduce the false alarm rate, and for classifying the remaining defects by size, area and type.

Abstract: To produce a screened color separation having any screen angle, an original picture is scanned to generate a set of picture values which are digitized and stored. Also a screen function is generated and stored representing a complete two-dimensional period of half-tone screen in the form of a grid-like array of grey-tone values, the mesh of the grid-like array being finer than the scanning raster. To expose a reproduction medium, the screen function values are superimposed on the picture values to develop exposure signals for an exposing plotter. The screen angle is selected by virtually rotating the stored screen function data through the selected angle as it is being recalled from memory.

Abstract: To produce a screened color separation having any screen angle, an original picture is scanned to generate a set of picture values which are digitized and stored. Also a screen function is generated and stored representing a complete two-dimensional period of a half-tone screen in the form of a grid-like array of grey-tone values, the mesh of the grid-like array being finer than the scanning raster. To expose a reproduction medium, the screen function values are superimposed on the picture values to develop exposure signals for an exposing plotter. The screen angle is selected by virtually rotating the stored screen function data through the selected angle as it is being recalled from memory.