Optical element with multiple primary light sources

1. An illumination system, comprising:

an optical element comprising a plurality of primary light sources and a plurality of reflective surfaces,

wherein the illumination system is configured so that during use of the illumination system:

the illumination system illuminates an area in a field plane;

each of the plurality of primary light sources illuminates a portion of the area in the field plane that is smaller than the area;

the plurality of reflective surfaces receive light from one or more of the plurality of primary light sources;

the plurality of primary light sources and the plurality of reflective surfaces are positionable relative to each other so that a plurality of light bundles originating from the multiple primary light sources are emitted in different directions; and

the plurality of primary light sources and the plurality of reflective surfaces are adjustable in their positions relative to each other by shifting and/or tilting individual primary light sources relative to respective reflective surfaces.

2. The illumination system according to claim 1 , wherein the optical element is arranged in a light source array.

3. The illumination system according to claim 1 , wherein at least one of the plurality of reflective surfaces is assigned to each of the plurality primary light sources.

4. The illumination system according to claim 1 , wherein the plurality of primary light sources and the reflective surfaces are adjustable in their positions relative to each other by shifting and/or tilting the reflective surfaces relative to respective individual primary light sources.

5. The illumination system according to claim 1 , wherein the plurality of reflective surfaces are elements of grazing-incidence collectors.

6. The illumination system according to claim 1 , wherein the plurality of reflective surfaces are elements of normal-incidence collectors.

7. The illumination system according to claim 1 , wherein the illumination system comprises a plurality of light source units, each light source unit comprises one of the plurality of primary light sources and one of the plurality of reflective surfaces, and the individual light source units are shiftable and/or tiltable relative to each other so that the light bundles associated with the different light source units are emitted in different directions.

8. The illumination system according to claim 1 , wherein at least one reflective surface has positive optical power selected so that a plurality of images of a respective primary light source are produced in the field plane.

9. The illumination system according to claim 1 , wherein:

the illumination system has an exit pupil;

the illumination system is configured so that during use of the illumination system the plurality of primary light sources illuminate an area in the exit pupil; and

the area is encircled by an exit pupil contour.

10. The illumination system according to claim 9 , wherein at least some of the plurality of primary light sources are capable of being switched on and off so that different exit pupil contours can be generated by selectively switching specific primary light sources on and off.

11. The illumination system according to claim 9 , wherein the illumination system is configured so that during use of the illumination system:

a first set of the plurality of primary light sources illuminates a first area in the exit pupil; and

a second set of the plurality of primary light sources illuminates a second area in the exit pupil.

12. The illumination system according to claim 11 , wherein the first area is encircled by an annular exit pupil contour, and the second area is encircled by a dipolar or quadrupolar exit pupil contour.

13. The illumination system according to claim 11 , wherein:

the optical element comprises reflective surfaces which receive light from one or more of the plurality of primary light sources; and

the reflective surfaces are capable of being changed in their positions relative to the primary light sources so that areas encircled by different exit pupil contours are illuminated during use of the illumination system.

14. The illumination system according to claim 1 , further comprising a concave mirror in a light path between the optical element and the field plane, wherein during use of the illumination system the concave mirror projects an image of the optical element into an exit pupil of the illumination system.

15. The illumination system according to claim 1 , wherein the illumination system is configured to be used in a microlithography projection exposure apparatus.

16. A projection exposure apparatus, comprising:

an illumination system according to claim 1 ; and

a projection objective.

17. The projection exposure apparatus according to claim 16 , wherein the projection exposure apparatus is a microlithography projection exposure apparatus.

18. The illumination system of claim 1 , wherein the illumination system is configured so that during use of the illumination system each of the plurality of primary light sources illuminates a portion of the area in the field plane that is less than 1/10 of a size of the area.

19. The illumination system of claim 1 , wherein the illumination system is configured so that during use of the illumination system each of the plurality of primary light sources illuminates a portion of the area in the field plane that is less than 1/50 of a size of the area.

20. The illumination system of claim 1 , wherein the illumination system is configured so that during use of the illumination system each of the plurality of primary light sources illuminates a portion of the area in the field plane that is less than 1/100 of a size of the area.

21. The illumination system of claim 1 , wherein the illumination system is configured so that during use of the illumination system each of the plurality of primary light sources illuminates a portion of the area in the field plane that is less than 1/1000 of a size of the area.