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X/Y Scanning at a Constant Angle of Incidence

IP.com Disclosure Number: IPCOM000078945D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Wojcik, WJ: AUTHOR

Abstract

In a spatial filtering optical system for aligning two objects, a constant angle of incidence of the alignment illumination is necessary. The system has a two-axis gimbal mirror which permits a constant angle of illumination of alignment patterns, whose positions vary in X and Y.

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X/Y Scanning at a Constant Angle of Incidence

In a spatial filtering optical system for aligning two objects, a constant angle of incidence of the alignment illumination is necessary. The system has a two- axis gimbal mirror which permits a constant angle of illumination of alignment patterns, whose positions vary in X and Y.

Fig. 1 shows the alignment optical system for aligning two objects 1 and 2, in which light from a source such as a laser is reflected from a mirror 3 through lens 4, object 1, lens 5, and object 2. Also shown are the paths to converging illumination beams 6 and 6' which strike two different alignment pattern locations 8 and 8', and 9 and 9' on objects 1 and 2 respectively. Beams 6 and 6' converge on two foci f and f', an intermediate and final focus, respectively. Although beams 6 and 6' converge to the same point, they pass through the point at different cone angles. A change in the beam angles at point f is related to a linear change of the X,Y beam position on the objects in a one-to-one correspondence.

A two-axis gimballed mirror 9'' is placed at point f, as shown in Fig. 2. The mirror provides angular rotation of beam 6'' around point f, and X,Y linear motion at the plane of object 2, at a constant angle of incidence.

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