Importance

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Abstract

A dual voice coil shutter is disclosed. The shutter mechanism is utilized in a stepper system, a laser system, or other carefully channeled light device to provide for opening and closing upon an optical path. The present invention is particularly useful for controlling passage of light hitting a photoresistive wafer through a reticle in a stepper system. The present invention provides a shutter type mechanism rotatably mounted about a common axis where the mechanism includes a pair of blades having a scissors-like arrangement adapted to simultaneously open and close upon an optical path. A voice type coil means is provided for each of the blades such that when a DC electrical current is applied to the coils, a rotation of the blades is effected about a single axis of rotation in a predetermined period of time. The rotation of the coils is coplanar. The present invention provides for net torque to the system that is in effect zero, which produces little or no mechanical operation in the rest of the structure which could otherwise cause inaccuracy in the mechanical positioning or delayed process time while waiting for oscillations to die out.

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First Claim