Device and method for the evanescent illumination of a sample
A device for the evanescent illumination of a sample, including an optical illumination element with an optical corrective element and an objective arranged downstream from the corrective element, to evanescently illuminate the sample with a supplied ray beam containing optical radiation with at least two different wavelengths. The corrective optical element has a transverse chromatic aberration which, during the illumination, leads to the optical radiation penetrating the pupil of the objective at different heights relative to the optical axis varying according to the wavelength. The corrective optical element is selected in such a way that the wavelength-related difference of the penetration depths of the radiation into the sample is reduced during the evanescent illumination.
1. A device for the evanescent illumination of a sample, comprising:
illumination optics including correction optics and an objective arranged downstream from said correction optics that evanescently illuminate the sample with a supplied ray bundle having optical radiation of at least two different wavelengths;
the correction optics having a transverse chromatic aberration which, during illumination, leads to the optical radiation traversing the pupil of the objective at different heights measured from an optical axis of the objective, the heights being different relative to the wavelength, and
the transverse chromatic aberration of the correction optics being selected such that the wavelength-related difference of penetration depths of the radiation into the sample is reduced during the evanescent illumination.
2. The device according to claim 1 , wherein the correction optics comprises at least one refractive element.
3. The device according to claim 1 , wherein the correction optics comprises at least one of an obliquely positioned planar plate and an obliquely positioned lens.
4. The device according to claim 1 , wherein the correction optics comprises a plane conjugated to the objective pupil, with the supplied ray bundle passing through said plane.
5. The device according to claim 1 , comprising a feed unit which feeds the ray bundle to the correction optics in an off-axis manner.
6. The device according to claim 5 , wherein the feed unit feeds the ray bundle of the correction optics in such a way that it does not extend parallel to the optical axis of the correction optics.
7. The device according to claim 1 , wherein the correction optics comprises at least one diffractive element.
8. A method of evanescent illumination of a sample, comprising:
directing a ray bundle containing optical radiation of at least two different wavelengths to a sample via correction optics and an objective arranged downstream from the correction optics such that the sample is illuminated evanescently;
selecting the correction optics to have a transverse chromatic aberration which, during illumination, leads to the optical radiation traversing the pupil of the objective at different heights varying according to the wavelength, the different heights being measured relative to an optical axis of the objective; and
selecting the transverse chromatic aberration such that the wavelength-related difference of penetration depths of the radiation into the sample is reduced during the evanescent illumination.
9. The method according to claim 8 , further comprising providing the correction optics with at least one refractive element and with at least one of an obliquely positioned planar plate and an obliquely positioned lens.
10. The method according to claim 8 , further comprising arranging the correction optics to have a plane conjugated to the objective pupil, with the supplied ray bundle passing through said plane.
11. The method according to claim 10 , further comprising arranging the delivery of the ray bundle that contains the optical radiation such that the ray bundle passes the conjugated plane as a coaxial ray bundle.
12. The method according to claim 8 , further comprising illuminating the sample with at least two wavelengths of the optical radiation simultaneously.
13. The method according to claim 8 , further comprising feeding the ray bundle to the correction optics in an off-axis manner.
14. The method according to claim 8 , further comprising feeding the ray bundle to the correction optics such that ray bundle does not extend parallel to the optical axis of the correction optics.
15. The method according to claim 8 , further comprising providing the correction optics with at least one diffractive element.