Optics for medical laser

Abstract

An optical system for use in a medical laser apparatus comprising an achromat having optical elements selected to cause two substantially different wavelengths, one visible and one infrared, to focus at a common focal point. The achromat comprises a negative lens and a doublet lens formed of a positive bi-convex lens and a negative meniscus lens. The materials of the two lenses which form the doublet have substantially different dispersions and indices of refraction and are chosen to cause a visible helium neon beam and an infrared carbon dioxide beam to focus at the same point. In the preferred embodiment of the present invention, the negative lens is made of zinc selenide, the bi-convex lens of the doublet is made of potassium chloride, and the negative meniscus is made of zinc selenide. The optical system of the present invention can be mounted in a micromanipulator for use in laser surgery. The visible helium neon beam is used as an aiming beam to establish a spot at which the carbon dioxide beam also focuses. The carbon dioxide beam is then employed to vaporize biotic material. A distal end of an articulated arm may couple with the micromanipulator to direct the carbon dioxide beam from the laser through a waveguide and into the micromanipulator. Another aspect of the invention includes introducing the aiming beam into the waveguide through a dichroic mirror positioned in a knuckle joint of the articulated arm. In one embodiment, a laser diode generates the visible light of the aiming beam, and is disposed proximate to the distal end of the articulated arm.