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US 12,729,984 B2Granted
Displacement detecting apparatus
AssigneeMagnescale Co., Ltd.
InventorsHideaki Tamiya, Shun Okuyama, Akinori Ebine
Life of this patent
Estimating the term…
Abstract
[Problem] To provide a displacement detection apparatus that offers high measurement accuracy while maintaining high versatility. [Solution] A second birefringent unit 121 and a third birefringent unit 123 are configured to change the phase difference between the first light beam L1 and the second light beam L2 in response to movement of the target T in the measurement direction.
Claims7
A displacement detection apparatus that detects displacement of a target in a measurement direction, comprising:
- a light source that emits light;
- a first birefringent unit that is provided in an optical path from the light source to the target to which the light is emitted, and splits the light into a first light beam and a second light beam having a phase difference with respect to the first light beam;
- a second birefringent unit that is provided in optical paths of the first light beam and the second light beam each reflected from the target and refracts the first light beam and the second light beam;
- a third birefringent unit that is provided in optical paths of the first light beam and the second light beam that have passed through the second birefringent unit, and converges the first light beam and the second light beam;
- a fourth birefringent unit that is provided in optical paths of the first light beam and the second light beam that have passed through the third birefringent unit, and superimposes the first light beam and the second light beam;
- and
- a displacement detection unit that detects displacement of the target in the measurement direction based on a change in the phase difference between the first light beam and the second light beam that have passed through the fourth birefringent unit,
- wherein the second birefringent unit and the third birefringent unit are configured to vary the phase difference between the first light beam and the second light beam according to movement of the target in the measurement direction.
5 more elements
A projection optical apparatus that transfers a pattern onto an object to be measured including a target, comprising:
- a mask on which a pattern to be transferred onto the object to be measured is formed;
- an exposure light source that exposes the object to be measured through the mask;
- a light source that is different from the exposure light source and emits light;
- a first birefringent unit that is provided in an optical path from the light source to the target to which the light is emitted, and splits the light into a first light beam and a second light beam having a phase difference with respect to the first light beam;
- a second birefringent unit that is provided in optical paths of the first light beam and the second light beam each reflected from the target and refracts the first light beam and the second light beam;
- a third birefringent unit that is provided on optical paths of the first light beam and the second light beam that have passed through the second birefringent unit and converges the first light beam and the second light beam;
- a fourth birefringent unit that is provided in optical paths of the first light beam and the second light beam that have passed through the third birefringent unit, and superimposes the first light beam and the second light beam;
- and
- a displacement detection unit that detects displacement of the target in the measurement direction based on a change in the phase difference between the first light beam and the second light beam that have passed through the fourth birefringent unit,
- wherein the second birefringent unit and the third birefringent unit are configured to vary the phase difference between the first light beam and the second light beam according to movement of the target in the measurement direction.
7 more elements
Dependencies are inferred from the claim text.