Methods and systems for laser calibration and eye tracker camera alignment
The present invention provides methods, systems, and apparatus for calibrating a laser ablation system, such as an excimer laser system for selectively ablating a cornea of a patient's eye. The invention also facilitates alignment of eye tracking cameras that measure a position of the eye during laser eye surgery. A calibration and alignment fixture for a scanning laser beam delivery system having eye tracking cameras may include a structure positionable in a treatment plane. The structure having a feature directing laser energy incident thereon to a calibration energy sensor, at least one reference-edge to determine a characteristic of the laser beam (shape, dimensions, etc.), and an artificial pupil to determine alignment of the eye tracking cameras with the laser system.
1. A method for characterizing a laser beam suitable for ablation of comeal tissue, the method comprising:
positioning a first sensor behind a beam splitter;
positioning a second sensor behind a calibration fixture;
transmitting a laser beam toward the beam splitter;
separating sample laser beam energy from the laser beam while transmitting;
measuring the sample laser beam energy with the first sensor;
scanning a laser beam across a calibration fixture having at least one reference-edge;
measuring the laser beam energy passing the reference-edge with the second sensor;
comparing a ratio of energy measured by the first and second sensors to a predetermined tolerance;
comparing the measurements from the first sensor to a first threshold range;
comparing the measurements from the second sensor to a second threshold range;
deriving a characteristic of the laser beam from the first and second threshold ranges; and
ablating a patient's cornea with the measured laser beam.
2. The method of claim 1 , wherein the laser is an excimer laser.
3. The method of claim 1 , wherein the laser is an solid state laser.
4. The method of claim 1 , wherein the laser beam is formed as a series of discrete pulses.
5. The method of claim 1 , wherein the sensor is a photodetector.