THIS PAPER DEALS WITH THE OPTICAL MATERIALS USED EITHER INTERNAL OR EXTERNAL TO ND-YAG AND CO2 LASERS. COMPARISONS ARE MADE WHERE APPROPRIATE. THIS INCLUDES TRANSMISSIVE AND REFLECTIVE OPTICS. ENHANCED AND ANTI-REFLECTION COATINGS ARE DISCUSSED. THE EFFECT OF POLARIZATION ON CUTTING AND THE METHOD FOR CONTROLLING THE PROBLEMS ARE COVERED. THE MATERIAL PRESENTED PROVIDES A BASIS FOR SELECTION OF THE PROPER OPTICAL ELEMENTS FOR SPECIFIC APPLICATIONS.
