Patent ID: 8915905

Claim:
Apparatus for ophthalmic laser surgery, comprising: a source of a pulsed femtosecond laser beam having a beam path, the pulsed femtosecond laser beam having an ultraviolet (UV) wavelength; a telescope expanding the laser beam, having an input lens taking the form of a controllable concave lens of variable refractive power and an exit lens taking the form of a convex lens of fixed refractive power, the controllable concave lens of variable refractive power being transparent within the range from about 300 nm to about 1300 nm; a scanner downstream of the telescope, for deflecting the laser beam in a plane perpendicular to the beam path; a focusing objective downstream of the scanner for focusing the laser beam, the focusing objective being an f-theta objective formed of two lenses and configured to bring about a plane-field image such that a beam focus of the laser beam lies in a plane orthogonal to the beam path independent of the deflection of the laser beam by the scanner; and a program-controlled electronic control arrangement in communication with at least the controllable concave lens of variable refractive power, the program-controlled electronic control arrangement controlling application of a voltage to the controllable concave lens of variable refractive power such that, for the purpose of achieving a predetermined incision profile for a lenticular extraction that requires displacements of the beam focus in the direction of the beam path to produce a curved front incision and a rear incision, a focus of the controllable concave lens of variable refractive power is adjusted based on the applied voltage to bring about the displacements of the beam focus in the direction of the beam path solely by control of the voltage applied to the controllable concave lens of variable refractive power, without changing a focussing setting of the focussing objective.