Patent ID: 11966041
Assignee: ZYGO CORPORATION
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An optical module for directing light rays between a first plane and a second plane, the optical module comprising:
a. at least three lens elements, wherein the lens elements collectively set a numerical aperture NA and a field height FH for directing the light rays between the first and second planes, and further collectively set a system effective focal length EFLsys, wherein NA, FH, and EFLsys satisfy:
i. 0<NA<0.25; and
ii. 0 <FH<(0.4)·(EFLsys),

b. wherein the at least three lens elements include first and second adjacent lens elements having effective focal lengths EFL1 and EFL2, respectively, satisfying:
i. (1.5)·(EFLsys)<EFL1<3·(EFLsys); and
ii. (1.5)·(EFLsys)<EFL2<3·(EFLsys),

c. wherein an air-distance between the first and second lens elements A12 satisfies:
i. 0<A12<EFLsys,

d. wherein the at least three lens elements includes a third lens element adjacent the second lens elements opposite the first lens element and having an effective focal length EFL3 satisfying:
i. (−20)·EFLsys<EFL3<(−1)EFLsys, and

e. wherein an air-distance between the second and third lens elements A23 satisfies:
i. 0<A23<EFLsys.