US 12,292,697 B2
Self-referencing interferometer and dual self-referencing interferometer devices
Douglas C. Cappelli, Norwalk, CT (US)
Assigned to ASML HOLDING N.V., Veldhoven (NL)
Appl. No. 17/614,159
Filed by ASML HOLDING N.V., Veldhoven (NL)
PCT Filed May 19, 2020, PCT No. PCT/EP2020/063882
§ 371(c)(1), (2) Date Nov. 24, 2021,
PCT Pub. No. WO2020/239516, PCT Pub. Date Dec. 3, 2020.
Claims priority of provisional application 62/854,398, filed on May 30, 2019.
Prior Publication US 2022/0221802 A1, Jul. 14, 2022
Int. Cl. G03F 9/00 (2006.01); G01B 9/02097 (2022.01)
CPC G03F 9/7049 (2013.01) [G01B 9/02097 (2013.01); G03F 9/7088 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A self-referencing interferometer (SRI) system for an alignment sensor apparatus, the SRI system comprising:
a first prism having an input surface for an incident beam; and
a second prism coupled to the first prism and having an output surface for a recombined beam,
wherein the recombined beam comprises a first image and a second image rotated within the first and second prisms by 180 degrees with respect to the first image,
wherein the first and second prisms are essentially identical in shape.