| abstract |
A fabrication method for a thallium-doped GRIN lens composed of a simplified glass composition is described and claimed. The composition is composed of silicon, oxygen, boron, zinc, potassium, sodium, and thallium. The method is comprised of preparing a cylindrical preform, annealing said cylindrical preform, removing contaminants from preform thereafter extruded to form a glass rod, exposing the glass rod to an alkali salt bath, and chemically milling the glass rod within an acid bath. Method and composition produce colorless lenses with a refractive index from 1.5900 to 1.7810, an insertion loss no greater than 0.05 dB, and a chromatic transmittance greater than 90 percent. |