Methods for globally treating silica optics to reduce optical damage
View Patent ↗A method for preventing damage caused by high intensity light sources to optical components includes annealing the optical component for a predetermined period. Another method includes etching the optical component in an etchant including fluoride and bi-fluoride ions. The method also includes ultrasonically agitating the etching solution during the process followed by rinsing of the optical component in a rinse bath.
1. A method for mitigating optical damage in an optical component, the method comprising:
providing an optical component having a region including optical damage precursors, the damage precursors including laser damage sites, scratches, and chemical impurities;
placing the optical component in an aqueous solution including species of one of hydrofluoric acid, fluoride ions, or bi-fluoride ions, the aqueous solution having an etch rate;
agitating the aqueous solution at a megasonic frequency after placing the optical component in the aqueous solution;
removing a surface layer from the region;
thereafter, placing the optical component in a rinse bath comprising deionized water for a first time duration and agitating the rinse bath at an ultrasonic frequency; and
after expiration of the first time duration, spray rinsing the optical component for a second time duration.
2. The method of claim 1 wherein removing the surface layer comprises removing about 100 nanometers to about 100 microns of material from the region.
3. The method of claim 1 wherein the second time duration is at least 15 minutes.
4. The method of claim 1 wherein the aqueous solution contains hydrofluoric acid and high purity water.
5. The method of claim 1 further comprising manipulating the etch rate of the aqueous solution to be lower than a removal rate for byproducts generated during the removing step.
6. The method of claim 1 wherein the aqueous solution is substantially free of cations capable of forming hexafluorosilicate salts with low solubility in the aqueous solution.
7. The method of claim 6 wherein the cations include one or more of sodium (Na + ), potassium (K + ), magnesium (Mg 2+ ) calcium (Ca 2+ ), barium (Ba 2+ ), zinc (Zn 2+ ), lead (Pb 2+ ), iron (Fe 2+ , Fe 3+ ), or aluminum (Al 3+ ).
8. The method of claim 1 further comprising adding ethylene diamine bifluoride, or fluoride salts of primary, secondary, or tertiary ammonium cations to the aqueous solution.
9. The method of claim 1 further comprising adding ammonium fluoride to the aqueous solution to stabilize pH concentration of the aqueous solution.
10. The method of claim 9 wherein the aqueous solution includes 1.2 moles per liter in hydrofluoric acid and 3 moles per liter in ammonium fluoride.
11. The method of claim 1 wherein the first time duration is at least 30 minutes.