Patent Number: 
Section: claims

1. An optical element, comprising:a substrate having first and second sides;a first coating supported by the first side of the substrate; anda second coating supported by the second side of the substrate,wherein:the substrate comprises a glass;the first coating reflects EUV radiation;the second coating transmits radiation at a first wavelength;the second coating comprises a member selected from the group consisting of an absorbing layer that absorbs radiation having a second wavelength and a transmitting layer that transmits radiation having the second wavelength;the first wavelength is in a range selected from the group consisting of the visible range and the infrared range;the second wavelength is in a range selected from the group consisting of the visible range and the infrared range;the second wavelength is different from the first wavelength; andthe optical element is an EUV mirror. 2. The optical element of claim 1, wherein the second coating further comprises an anti-reflecting layer that suppresses reflection of radiation at the second wavelength, and the absorbing layer is between the substrate and the anti-reflection layer. 3. The optical element of claim 2, wherein a maximum absorbance of the absorbing layer is at wavelengths of more than 1500 nm. 4. The optical element of claim 3, wherein a maximum suppression of the anti-reflection layer is at wavelengths of more than 1500 nm. 5. The optical element of claim 2, wherein a maximum suppression of the anti-reflection layer is at wavelengths of more than 1500 nm. 6. The optical element of claim 1, wherein the absorbing layer has a maximum transmission at wavelengths less than 1500 nm. 7. The optical element of claim 1, wherein the substrate comprises a material that is at least partially absorbent for radiation at the second wavelength. 8. The optical element of claim 7, wherein the substrate comprises a material that is at least partially transparent for radiation at the first wavelength. 9. The optical element of claim 1, wherein the substrate comprises a material that is at least partially transparent for radiation at the first wavelength. 10. The optical element of claim 1, wherein the second coating further comprises an anti-reflecting layer that suppresses reflection of radiation at the first wavelength and at the second wavelength, and the transmitting layer is between the substrate and the anti-reflection layer. 11. The optical element of claim 1, wherein the glass comprises a silicate glass. 12. The optical element of claim 1, wherein the glass comprises a quartz glass. 13. The optical element of claim 1, wherein the glass comprises a TiO2-doped quartz glass. 14. The optical element of claim 1, wherein the glass comprises a glass ceramic. 15. The optical element of claim 1, wherein the second coating comprises an absorbing layer that absorbs radiation having the second wavelength. 16. The optical element of claim 1, wherein the second coating comprises a transmitting layer that transmits radiation having the second wavelength. 17. An arrangement, comprising:an optical element according to claim 1; anda light source configured to generate radiation at a wavelength in a range selected from the group consisting of visible radiation and infrared radiation,wherein the second coating is between the light source and the substrate. 18. The arrangement of claim 17, wherein:the arrangement comprises a plurality of light sources in a grid-type arrangement; andfor each light source, the second coating is between the light source and the substrate. 19. The arrangement of claim 18, wherein the arrangement is an EUV lithography apparatus. 20. The arrangement of claim 17, wherein the arrangement is an EUV lithography apparatus.