Interferometric plural-dimensional displacement measuring system
First Claim
1. A plural-dimensional displacement measuring system for an apparatus having a bed (10), a first stage (12) movable in a first direction (Y) relative to the bed and a second stage (18) movable in a second direction (X), generally at right angles to the first direction, relative to the first stage, the measuring system employing a first interferometer system (FIG. 5A) for measuring linear displacement generally in the first direction between a first reference reflector (66) and a first target reflector (70) fixed relative to the first stage and producing a corresponding first output signal, a second interferometer system (FIG. 5B) for measuring linear displacement generally in the second direction between a second reference reflector (72) and a second target reflector (82) fixed relative to the second stage and producing a corresponding second output signal, and means (64) for processing the output signals to determine linear displacement of the second stage relative to the bed in the first and second directions, characterised in that:
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the second interferometer system includes a intermediate reflector (74) fixed relative to the first stage and is arranged to produce a beam (98,100) that extends generally in the first direction from a position fixed relative to the bed to the intermediate reflector and that, upon reflection thereby, extends generally in the second direction from the intermediate reflector to the second target reflector.
2 Assignments
0 Petitions
Accused Products
Abstract
Interferometric two-dimensional displacement measuring system A measuring system for an apparatus having a bed, a first stage movable in a first direction relative to the bed, and a second stage movable in a second direction at right angles to the first direction, relative to the first stage. A first interferometer measures displacement in the first direction between a first reference reflector and a first target reflector fixed to the first stage. A second interferometer (a) measures displacement in the second direction between a second reference reflector and a second target reflector fixed to the second stage, (b) includes an intermediate reflector fixed to the first stage, (c) produces a beam that extends in the first direction from a position fixed to the bed to the intermediate reflector and in the second direction from the intermediate reflector to the second target reflector and (d) can therefore have a head that is mounted on the bed.
6 Citations
11 Claims
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1. A plural-dimensional displacement measuring system for an apparatus having a bed (10), a first stage (12) movable in a first direction (Y) relative to the bed and a second stage (18) movable in a second direction (X), generally at right angles to the first direction, relative to the first stage, the measuring system employing a first interferometer system (FIG. 5A) for measuring linear displacement generally in the first direction between a first reference reflector (66) and a first target reflector (70) fixed relative to the first stage and producing a corresponding first output signal, a second interferometer system (FIG. 5B) for measuring linear displacement generally in the second direction between a second reference reflector (72) and a second target reflector (82) fixed relative to the second stage and producing a corresponding second output signal, and means (64) for processing the output signals to determine linear displacement of the second stage relative to the bed in the first and second directions,
characterised in that: - —
the second interferometer system includes a intermediate reflector (74) fixed relative to the first stage and is arranged to produce a beam (98,100) that extends generally in the first direction from a position fixed relative to the bed to the intermediate reflector and that, upon reflection thereby, extends generally in the second direction from the intermediate reflector to the second target reflector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of setting up a measuring system having a bed (10), a first stage (12) movable in a first direction (Y) relative to the bed, a second stage (18) movable in a second direction (X), generally at right angles to the first direction, relative to the first stage, and a plural-dimensional displacement measuring system employing a first interferometer system (FIG. 5A) for measuring linear displacement generally in the first direction between a first reference reflector (66) and a first target reflector (70) fixed relative to the first stage and producing a corresponding first output signal, a second interferometer system (FIG. 5B) for measuring linear displacement generally in the second direction between a second reference reflector (72) and a second target reflector (82) fixed relative to the second stage and producing a corresponding second output signal, and means (64) for processing the output signals to determine linear displacement of the second stage relative to the bed in the first and second directions, the second interferometer system including a intermediate reflector (74) fixed relative to the first stage and arranged to produce a beam (98,100) that extends generally in the first direction from a position fixed relative to the bed to the intermediate reflector and that, upon reflection thereby, extends generally in the second direction from the intermediate reflector to the second target reflector, the method comprising the steps of:
- adjusting the orientation of the first interferometer system so that the measuring direction thereof is parallel to the direction of movement of the first stage relative to the bed; and
adjusting the orientation of the first stage at a reference position so that the direction of movement of the second stage relative to the first stage at that reference position is parallel to the measuring direction of the second interferometer system.
- adjusting the orientation of the first interferometer system so that the measuring direction thereof is parallel to the direction of movement of the first stage relative to the bed; and
Specification