Spot size reduction in coupling of laser to micromanipulator in laser microsurgery by fiberoptic link.

Abstract

In coupling laser with micromanipulator through fiberoptics, the resulting diameter of the spot is limited by the laws of geometrical optics, because of the high numerical aperture (N.A.) of fiberoptic radiation. A new method for the reduction of spot size diameter is suggested. The output of a 2 mW He-Ne laser was couped via fiberoptic link, the fiberoptic output light collected by a single lens collimator and directed to the input of the micromanipulator. The spot size can be considerably reduced by the introduction of an aperture which reduces the numerical aperture (N.A.) of the fiberoptic. The resulting reduction in total power has little effect on the power density. This approach to the collimator design permits reduction in spot size without any significant changes in power density, thus avoiding damage to the tissue and obtaining optimum performance from the micromanipulator.