Method and system for automatic target finding

A method for creating a recipe for use in processing a patterned article, which contains targets located in spaces between periodically repeated patterned fields, the method comprising identifying at least one target on the article and recording the target location, wherein said identifying comprises:

• first imaging the article with relatively low magnification defining a first field of view, and generating first measured data indicative thereof;
• analyzing the first measured data to identify a region of interest within the first field of view, said region of interest being that of a potential location of the target;
• applying an area imaging device having relatively high magnification defining a second field of view, to scan the region of interest with a predetermined speed of scanning and a predetermined rate of image acquisition during the scanning, and generating second measured data indicative of a high resolution image of the region of interest;
• analyzing the second measured data to identify the existence of the target in a location in said region of interest, thereby enabling high magnification imaging of the identified target location to verify the target location and determine coordinates of said location.

A system for use in automatic identification of a target on a patterned article, which contains targets located in spaces between periodically repeated patterned fields, the system comprising:

• a measuring unit including an optical arrangement defining a relatively low-magnification imaging channel and a relatively high-magnification imaging channel, wherein said relatively high-magnification imaging channel includes an area imaging device;
• a drive assembly operable to provide a relative displacement between an optical head of said measuring unit and the article in a horizontal plane;
• and
• a control unit connectable to the measuring unit and to the drive assembly, said control unit being preprogrammed for:
• operating the measuring unit to apply first imaging of the article with the relatively low magnification and generate first measured data indicative of a region of interest on the article,
• for operating the measuring unit and the drive assembly to apply the high-magnification scanning of the region of interest with a predetermined speed of scanning and a predetermined rate of image acquisition during the scanning and generate second measured data representative of a high resolution image of the region of interest, and
• for analyzing the second measured data to identify the existence of the target in a location in said region of interest, thereby enabling high magnification imaging of the identified target location to verify the target location and determine coordinates of said location.