PATENT CLAIM ANALYSIS

Application Number: 15889412
Application Type: Utility
Filing Date: 2018-02
Publication Date: 2018-06
Patent Classification: ["356", "508000"]

Abstract:
An encoder head configured for use with a lithographic exposure tool. The head is devoid of the multiplicity of optical corner-cubes and includes, instead, a single, geometrically substantially perfect cuboid of optically-isotropic material complemented, in operation, with a birefringent lens to form a contraption that, as a unit, splits a single beam of light delivered to the contraption into four measurement (sub-)beams of light (two in xz-plane, two in yz-plane) and causes each of measurement sub-beams to interact with the wafer-stage diffraction grating at the same location twice: upon the first pass by the grating and upon the second pass by the grating. The use of the contraption solves problems of (i) structural complexity of a conventional encoder head for use in an exposure tool, (ii) burdensome alignment of the multitude of optical prisms in the process of forming such encoder head, and (iii) cyclic non-linear errors associated with measurements involving conventional corner-cubes-based encoder heads while, at the same time, reducing the geometrical footprint of the encoder head. The contraption is complemented with a birefringent prismatic element positioned across the axis of the contraption between the cuboid and the birefringent lens.

Claim (Index 2):
The optical system according to  claim 1 , wherein the at least one birefringent lens element includes first and second birefringent lens elements having, respectively, first and second crystal axes, the first and second crystal axes being transverse to one another.

Metadata:
- Claim Count in Document: 83.0
- Percentile: 88.0
- Lexical Diversity: 2.02778
- Patent Class: 356.0
- Transitional Phrase Type: none
- Component Type: 0
- Foreign Priority: False
- Related Applications: ['15800480', '15866696', '15483887', '14880812', '13796316']

Analysis Scores:
- 35 USC 101 Eligibility (BERT): 0.7571159756768114
- 35 USC 102 Novelty (BERT): 0.5307899677673207
- Combined Prediction Score: 0.7344833748858625
- Mean Citation Score: 310.103094
- Max Citation Score: 366.1359
- Similarity Product: 288.2524618620157

Labels:
- Claim Label 101: 1
- Claim Label 102: 0
- Claim Label 103: 0
- Claim Label 112: 1
- Combined Label: 0
- Label 101 Adjusted: 1

Dataset: test