Patent Number: 
Section: claims

1. An optical system for illuminating a sample with a line beam, the system comprising:a light source;a beam shaper for transforming the beam of light emitted by the light source into an intermediate astigmatic image by changing a position of the beam shaper relative to the light source; andan imaging system for transforming the intermediate astigmatic image into a final astigmatic image and for illuminating the sample with the line beam,wherein the beam shaper provides different non-unity magnifications in a lateral plane and in a transversal plane, and comprises a toroidal entrance surface and a toroidal exit surface, each with finite radii of curvature. 2. The optical system as claimed in claim 1, wherein the final astigmatic image comprises a line focus. 3. The optical system as claimed in claim 2, wherein a width of the line beam is diffraction limited. 4. An optical system as claimed in claim 1, wherein a ratio (a) of a length of one of focal lines of the final astigmatic image to (b) a distance between the beam shaper and the position of the beam shaper for which an astigmatic distance of the intermediate image is zero is given by:      NA    ⁡          (                        M          x          2                -                  M          y          2                    )                  (              M        2            )        ⁢                  1        -                              NA            2                                n            2                              where n is a refractive index of the sample, NA is an exit numerical aperture of the imaging system, M is a magnification of the imaging system and Mx and My are a first magnification and a second magnification of the beam shaper for the two focal lines of the intermediate image. 5. The optical system of claim 1, wherein the beam shaper is moveable back and forth towards the light source to provide a desired elongation of the line beam. 6. A detection device, comprising:an optical system for illuminating a sample with a line beam, the system comprising:a light source;a beam shaper for transforming the beam of light emitted by the light source into an intermediate astigmatic image by changing a position of the beam shaper relative to the light source; andan imaging system for transforming the intermediate astigmatic image into a final astigmatic image and for illuminating the sample with the line beam, wherein the beam shaper provides different non-unity magnifications in a lateral plane and in a transversal plane, and comprises a toroidal entrance surface and a toroidal exit surface, each with finite radii of curvature;an optical collection arrangement for collecting light emitted from the sample and generated by the line beam and;a detection system for detecting the collected light. 7. The detection device as claimed in claim 6, wherein the imaging system and the optical collection arrangement share an excitation/collection lens. 8. The detection device as claimed in claim 6, wherein the detection system comprises an imaging lens which focuses onto a detection surface of the detection system. 9. The detection device as claimed in claim 6, wherein the light emitted from the sample and generated by the line beam comprises luminescence light. 10. The detection device of claim 6, wherein the beam shaper is moveable back and forth towards the light source to provide a desired elongation of the line beam. 11. An illumination method for illuminating a sample with a line beam, comprising the acts of:generating a beam of light using a light source;transforming the beam of light into an intermediate astigmatic image using a beam shaper by changing a position of the beam shaper relative to the light source; andtransforming the intermediate astigmatic image into a final astigmatic image using an imaging system for illuminating the sample with the line beam,wherein the beam shaper provides different non-unity magnifications in a lateral plane and in a transversal plane, and comprises a toroidal entrance surface and a toroidal exit surface, each with finite radii of curvature. 12. The illumination method of claim 11, wherein the beam shaper is moveable back and forth towards the light source to provide a desired elongation of the line beam.