Patent Number: 
Section: claims

1. A filter system for filtering debris particles out of radiation emitted by a radiation source, and usable for lithography, the filter system comprising:a plurality of foils configured to trap the debris particles,at least one foil of the plurality of foils including at least two parts that have a mutually different orientation and that are connected to each other along a substantially straight connection line,each of the at least two parts substantially coinciding with a respective virtual plane, wherein each of the virtual planes extends through a predetermined position that substantially coincides with the radiation source,the substantially straight connection line coinciding with a virtual straight line that also extends through the predetermined position. 2. A filter system according to claim 1, wherein the filter system includes a support to which a first part of the at least two parts is connected at a first position of the support and to which a second part of the at least two parts is connected at a second position of the support. 3. A filter system according to claim 2, wherein a distance between the first and second position is fixed. 4. A filter system according to claim 2, wherein the support comprises an inner ring and an outer ring. 5. A filter system according to claim 4, wherein the inner ring and the outer ring are coaxial. 6. A filter system according to claim 2, wherein at least a part of the filter system is arranged to cool the support. 7. A filter system according to claim 2, wherein the filter system further includes a cooling system having a surface that is arranged to be cooled, the cooling system and the support being positioned with respect to each other such that a gap is formed between the surface of the cooling system and the support, and wherein the cooling system further is arranged to inject gas into the gap. 8. A filter system according to claim 7, wherein a path between an entrance position at which the gas enters the gap and an exit position from which the gas exits the gap forms a meandering path. 9. A filter system according to claim 7, wherein the gap is such that a smallest distance between the surface of the cooling system and the support is in a range from about 20 micrometers to about 200 micrometers. 10. A filter system according to claim 9, wherein the gap is such that a smallest distance between the surface of the cooling system and the support is in a range from about 40 micrometers to about 100 micrometers. 11. A filter system according to claim 7, wherein the support is rotatable with respect to the surface of the cooling system. 12. A filter system according to claim 7, wherein the surface of the cooling system is arranged to be stationary with respect to the support. 13. A filter system according to claim 7, wherein the surface of the cooling system is arranged to be cooled with a fluid. 14. A filter system according to claim 13, wherein the fluid is water. 15. A filter system according to claim 7, wherein the gas is argon. 16. A filter system according to claim 7, wherein the support is provided with a recess for holding the cooled gas before the cooled gas flows through the gap. 17. A filter system according to claim 1, wherein at least one of the at least two parts coincides with a virtual plane that is a straight plane. 18. A filter system according to claim 1, wherein the cooling system is arranged to cool the gas before injecting the gas in the gap. 19. A filter system according to claim 1, wherein each virtual plane is a straight plane. 20. A filter system according to claim 1, wherein at least one of the at least two foil parts includes a curvature. 21. A filter system according to claim 1, wherein the at least two foil parts are configured to accommodate thermal expansion by a substantially sideways movement of the connection line with respect to the overall orientation of the foil.