| 摘要 |
In order to determine the focus position of a laser beam (60, 60a) in an ophthalmological laser projection system (1), at least one measurement marking (3) applied to a reference area (20) is passed over by means of the laser beam (60, 60a) along a scanning path. A measurement signal created by passing over the measurement marking (3) is captured. Time values from at least one signal edge created in the measurement signal when passing over edges of the measurement marking (3) are determined and the focus position is established on the basis of the time values. By scanning defined measurement markings (3) and establishing time values of signal edges created when edges of the measurement marking (3) are passed over, it is possible to determine the focus position of the laser beam (60, 60a) without focusing movements being required for this during the measurement. |
| 主权项 |
1. A method for determining the focus position of a laser beam in an ophthalmological laser projection system for projecting the laser beam along a beam path in a focused manner into eye tissue, comprising the steps of:
arranging a reference area in said beam path of the ophthalmological laser projection system, projecting the laser beam from the ophthalmological laser projection system in a projection direction along said beam path, moving the laser beam by a scanner of the ophthalmological laser projection system along a scanning path and passing the laser beam along the scanning path over at least one measurement marking applied on the reference area arranged in the beam path, and creating a measurement signal when passing the laser beam along the scanning path over the measurement marking, the measurement signal having at least one signal edge created in the measurement signal when passing the laser beam along the scanning path over edges of the measurement marking, capturing the measurement signal created by and when passing the laser beam along the scanning path over the measurement marking, determining time values of the at least one signal edge created in the measurement signal when passing the laser beam along the scanning path over edges of the measurement marking, at least one time value corresponding to an upper signal threshold on the at least one signal edge and at least another time value corresponding to a lower signal threshold, the upper and the lower signal thresholds being lower than a maximum value and higher than a minimum value along the at least one signal edge, and establishing the focus position of the laser beam in the projection direction along said beam path of the ophthalmological laser projection system on the basis of the time values, wherein a time duration between the upper and the lower signal thresholds is determined, a beam width is determined on the basis of the time duration, and the focus position in the projection direction of the laser beam is established on the basis of the beam width. |
