THE EXCIMER LASER - HOW IT WORKS

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A simple way to imagine how the laser works is to think of it as placing the curvature from your glasses or contact lenses onto the front surface of your eye, allowing you to see without corrective eyewear.

The following description applies only to the VISX STAR S4 Excimer Laser. The VISX STAR S4 Excimer Laser is the best laser available on the U.S. market today:
The energy output of the excimer laser is precisely controlled by diluting the active argon and fluorine gases within the laser cavity with inert helium gas. This is the coarse control of the energy output of the laser. The fine control of the energy output is acquired by applying varying amounts of high voltage across the laser cavity. In this manner, the energy output of the excimer laser, called fluence, is precisely controlled.

The ultraviolet light of the laser cavity is then directed by mirrors and lenses to the beam homogenizer , then onto the beam shaping modules and finally onto the patient's eye. The mirrors, lenses, homogenizers and beam shaping modules are physically attached to the laser rail. The laser rail is simply a structurally ridged piece of alloy metal that is solidly affixed to the laser cavity so that precise alignment of all components is possible.
The beam homogenizer smoothes out any small inconsistencies in the laser beam energy profile. This is called a rotating dove tail prism. This is also responsible for the scanning characteristics of the VISX Star S4 laser.

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