Process for production of high efficiency volume diffractive elements in photo-thermo-refractive glass

A method of forming diffractive optical elements, comprising the steps of:

• (a) making a photo-thermo-refractive (PTR) glass which shows a refractive index increment after exposure to optical radiation followed by thermal treatment, having a level of less than approximately 5 ppm of impurities of iron and heavy metals, wherein the PTR glass includes:
• oxides of sodium, zinc, aluminum, and silicon as main components;
• and cerium, silver, tin, antimony, fluorine, and bromine as dopants;
• (b) exposing the PTR glass to radiation in the spectral region of its photosensitivity of ultraviolet radiation ranging from approximately 280 to approximately 380 nm;
• and
• (c) increasing absolute diffraction efficiency of the PTR glass to at least 95% by thermal treating of the PTR glass in the temperature region ranging from approximately 480 to approximately 580° C. for a period of from a few minutes to several hours appropriate for phase transformation of exposed area from steps (a), (b), (c), whereby holographic optical elements are formed.

A method of forming diffractive optical elements, comprising the steps of:

• (a) making a photo-thermo-refractive (PTR) glass which shows a refractive index increment after exposure to optical radiation followed by thermal treatment, having a level of less than approximately 5 ppm of impurities of iron and heavy metals, wherein the PTR glass includes (mol. %):
• 13.6Na2O-5.2ZnO-2.3Al2O3-72.3SiO2-3.7NaF-1.5KBr-1.2AIF3 doped with 0.01Ag2O-0.01CeO2-0.01 SnO2-0.03 Sb2O3;
• (b) exposing the PTR glass to radiation in the spectral region of its photosensitivity of ultraviolet radiation ranging from approximately 280 to approximately 380 nm;
• and
• (c) increasing absolute diffraction efficiency of the PTR glass to at least 95% by thermal treating of the PTR glass in the temperature region ranging from approximately 480 to approximately 580° C. for a period of from a few minutes to several hours appropriate for phase transformation of exposed area from steps (a), (b), (c), whereby holographic optical elements are formed.