Broad spectrum ultraviolet inspection methods employing catadioptric imaging

Patent 6313467 Issued on November 6, 2001. Estimated Expiration Date:

June 16, 2020. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

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Inventors

Application

No. 596540 filed on 06/16/2000

US Classes:

250/372, Ultraviolet light responsive means250/461.1With ultraviolet source

Examiners

Primary: Hannaher, Constantine
Assistant: Israel, Andrew

Attorney, Agent or Firm

Conley, Rose & Tayon, PC, Meyertons; Eric B.

Foreign Patent References

0 204 071 EP. 12/13/1986
0 405 051 EP. 01/13/1991
0 628 806 EP. 12/13/1994
0 736 789 EP. 10/13/1996
2 158 675 GB. 11/13/1985
85/00408 WO. 01/13/1985
86/01096 WO. 02/13/1986
86/02730 WO. 05/13/1986
86/07148 WO. 12/13/1986

International Class

G01N 021/64

Abstract

An ultraviolet (UV) catadioptric imaging system, with broad spectrum correction of primary and residual, longitudinal and lateral, chromatic aberrations for wavelengths extending into the deep UV (as short as about 0.16 μm), comprises a focusing lens group with multiple lens elements that provide high levels of correction of both image aberrations and chromatic variation of aberrations over a selected wavelength band, a field lens group formed from lens elements with at least two different refractive materials, such as silica and a fluoride glass, and a catadioptric group including a concave reflective surface providing most of the focusing power of the system and a thick lens providing primary color correction in combination with the focusing lens group. The field lens group is located near the intermediate image provided by the focusing lens group and functions to correct the residual chromatic aberrations. The system is characterized by a high numerical aperture (typ. greater than 0.7) and a large flat field (with a size on the order of 0.5 mm). The broad band color correction allows a wide range of possible UV imaging applications at multiple wavelengths.