Device and method for measuring surface topography and wave aberration of a lens system, in particular an eye
A device and a method are used for measuring the surface topography and a wave aberration of a lens system. The device is fitted with a first measuring system containing a light source radiating a first light beam of a first wavelength, and a detector which captures the first light beam which is reflected on the lens system. In addition the device has a second measuring system containing a light source for radiating a second light beam of a second wavelength and a detector for capturing the second light beam transmitted by the lens system. A diffractive optical element is disposed in a common beam path of the first measuring system and second measuring system. The optical element adapts the respective wave-front course of the first light beam and the second light beam in a wavelength-selective manner.
1. A device for measuring a topography and a wave aberration of a lens systems, the device comprising:
a first measuring system having a first light source for emitting a first light bundle of a first wavelength, and a first detector for picking up the first light bundle reflected at the lens system;
a second measuring system having a second light source for emitting a second light bundle of a second wavelength and a second detector for picking up the second light bundle transmitted through the lens system; and
a diffractive optical element disposed in a common beam path region of said first and second measuring systems, said diffractive optical element adapting a respective wave-front profile of the first light bundle and of the second light bundle in a wavelength-selective fashion.
2. The device according to claim 1 , wherein said diffractive optical element suppresses a zeroth diffraction order of the first light bundle, while the second light bundle is transmitted substantially undisturbed into the zeroth diffraction order.
3. The device according to claim 1 , wherein said diffractive optical element preadapts the wave-front profile of the first light bundle to a topography of the lens system.
4. The device according to claim 1 , wherein the wave-front profile of the second light bundle is substantially unmodified by said diffractive optical element.
5. The device according to claim 1 , wherein said diffractive optical element is a surface-corrugated phase element.
6. The device according to claim 1 , further comprising a third light source for emitting a third light bundle of a third wavelength for inserting a fixation target into the lens system.
7. The device according to claim 6 , wherein the third wavelength corresponds to the second wavelength.
8. The device according to claim 1 , wherein said first and second detectors are a common detector for said first and second measuring systems.
9. The device according to claim 1 , wherein at least the first wavelength lies in the infrared spectral region.
10. The device according to claim 1 , further comprising an adjusting configuration for setting a position of the lens system with reference to said diffractive optical element.
11. The device according to claim 10 , wherein said adjusting configuration includes a light source for casting an adjusting light beam onto the lens system at an angle, and a position-sensitive detector for determining a position of the adjusting light beam reflected at the lens system.
12. The device according to claim 1 , wherein said diffractive optical element is disposed directly upstream of the lens system.
13. The device according to claim 1 , further comprising a wavelength-selective beam splitter limiting said common beam path region.
14. The device according to claim 13 , wherein said wavelength-selective beam splitter is a diffractive optical element.
15. The device according to claim 1 , wherein at least one of said first detector and said second detector is a Shack-Hartmann sensor.
16. The device according to claim 1 , wherein at least one of said first detector and said second detector is an interferometer.
17. A method for measuring a topography and a wave aberration of a lens system, which comprises the steps of:
casting a first light bundle of a first wavelength onto the lens system for measuring the topography;
detecting the first light bundle reflected by the lens system;
casting a second light bundle of a second wavelength onto the lens system for measuring the wave aberration;
detecting the second light bundle transmitted through the lens system; and
adapting a respective wave-front profile of the first light bundle and of the second light bundle in a wavelength-selective fashion by a diffractive optical element positioned in a common beam path region of the first light bundle and of the second light bundle.
18. The method according to claim 17 , which further comprises selecting the first wavelength and the second wavelength with regard to the diffractive optical element such that a zeroth diffraction order of the first light bundle is suppressed by the diffractive optical element, while the second light bundle is transmitted substantially unattenuated into the zeroth diffraction order.
19. The method according to claim 17 , which further comprises preadapting the wave-front profile of the first light bundle to the topography of the lens system using the diffractive optical element.
20. The method according to claim 17 , which further comprises measuring the topography and the wave aberration simultaneously.
21. The method according to claim 17 , which further comprises measuring the topography and the wave aberration sequentially in time.
22. The method according to claim 17 , which further comprises performing a scanning spot method for measuring the topography and/or the wave aberration.