Deep UV telecentric imaging system with axisymmetric birefringent element and polar-orthogonal polarization

• US 20080013165A1
• Filed: 08/03/2006
• Published: 01/17/2008
• Est. Priority Date: 08/03/2005
• Status: Abandoned Application

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Webb, James
• Application Number:
  US11/498,639
• Publication Number:
  US 20080013165A1
• Time in Patent Office: Days
• US Class Current: 359/352
• CPC Class Codes: G02B 13/143 for use with ultraviolet radiation
• CPC Class Codes: G02B 13/22 Telecentric objectives or lens systems
• CPC Class Codes: G02B 27/283 used for beam splitting or combining
• CPC Class Codes: G02B 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• CPC Class Codes: G03F 7/70966 Birefringence

Abstract

Axisymmetric birefringent materials are incorporated into a deep UV imaging system by exploiting axial symmetries. A polar orthogonal polarization pattern is relayed conjugate to a pupil of a telecentric imaging system to avoid birefringence of axisymmetric birefringent optics located in telecentric object or image space.

Claims

1. A telecentric imaging system aligning polar-orthogonally polarized light with an axisymmetric birefringent element.

2. The telecentric imaging system of claim 1 in which the polar-orthogonally polarized light has a polarization axis about which electric field vectors are symmetrically arranged, the axisymmetric birefringent element has a birefringence axis about which birefringence is symmetrically arranged, and the polarization axis of the polar-orthogonally polarized light is aligned with the birefringence axis of the axisymmetric birefringent element.

3. The telecentric imaging system of claim 2 in which the axisymmetric birefringent element is located within a telecentric space in which chief rays of object or image points are aligned with both the polarization axis of the polar-orthogonally polarized light and the birefringence axis of the axisymmetric birefringent element.

4. The telecentric imaging system of claim 2 in which the telecentric imaging system is a reducing system, and the axisymmetric birefringent element is located within telecentric image space.

5. The telecentric imaging system of claim 4 in which the axisymmetric birefringent element is formed at least in part of sapphire.

6. The system of claim 1 in which the axisymmetric birefringent element separates polarized rays into extraordinary and ordinary rays, and the polar-orthogonally polarized light transmits through the axisymmetric birefringent element as substantially one or the other of the extraordinary and ordinary rays.

7. The telecentric imaging system of claim 6 in which the axisymmetric birefringent element exhibits a birefringence difference between ordinary and extraordinary rays of at least 0.0005.

8. The telecentric imaging system of claim 6 in which the polar-orthogonally polarized light is azimuthally polarized and transmits through the axisymmetric birefringent element as ordinary rays.

9. The telecentric imaging system of claim 6 in which the polar-orthogonally polarized light is radially polarized and transmits through the axisymmetric birefringent element as extraordinary rays.

10. The telecentric imaging system of claim 9 in which in which the axisymmetric birefringent element exhibits a refractive index that varies with inclinations of the extraordinary rays producing a wavefront alteration that compensates for one or more other wavefront alterations of the telecentric imaging system.

11. The telecentric imaging system of claim 1 in which the axisymmetric birefringent element contributes optical power to the telecentric optical system.

12. The telecentric imaging system of claim 11 in which the axisymmetric birefringent element is a solid optical element that exhibits an average refractive index that is higher than other solid optical elements of the telecentric imaging system.

13. The telecentric imaging system of claim 12 in which the axisymmetric birefringent element increases a numerical aperture of the telecentric imaging system.

14. The telecentric imaging system of claim 1 further comprising an illuminating system that arranges the polar-orthogonally polarized light conjugate to a pupil of the telecentric imaging system.

15. A deep UV imaging system comprising

an arrangement of optical elements for forming an image of an object,

an illuminator that produces deep UV polar-orthogonally polarized light,

at least one of the optical elements being an axisymmetric birefringent element exhibiting a birefringence difference between ordinary and extraordinary rays, and

the axisymmetric birefringent element being oriented with respect to the polar-orthogonally polarized light such that the-polar-orthogonally polarized light propagates through the axisymmetric birefringent element as substantially one or the other of the ordinary and extraordinary rays.

16. The imaging system of claim 15 including a pupil, and in which the illuminator produces the polar-orthogonally polarized light substantially conjugate to the pupil.

17. The imaging system of claim 16 in which the axisymmetric birefringent element is located in a telecentric space in which chief rays of object or image points extend substantially parallel to both a polarization axis of the polar-orthogonally polarized light and a birefringence axis of the axisymmetric birefringent element.

18. The imaging system of claim 17 in which the axisymmetric birefringent element is made from a uniaxial crystal having an optical axis aligned with both the polarization axis and the chief rays.

19. The imaging system of claim 18 in which birefringence is minimized along the optical axis of the uniaxial crystal.

20. The imaging system of claim 18 in which the axisymmetric birefringent element exhibits a birefringence difference between ordinary and extraordinary rays of at least 0.0005.

21. The imaging system of claim 17 in which the axisymmetric birefringent element contributes optical power to the imaging system.

22. The imaging system of claim 21 in which the axisymmetric birefringent element increases a numerical aperture of the imaging system.

23. The imaging system of claim 17 in which the axisymmetric birefringent element has an average refractive index substantially above an average refractive index of the other optical elements.

24. The imaging system of claim 17 in which the axisymmetric birefringent element has a melting point substantially above an average melting point of the other optical elements.