Lithium containing glass with high oxidized iron content, and laminated transparency using same
A low infrared absorbing lithium glass includes FeO in the range of 0.0005-0.015 wt %, more preferably 0.001-0.010 wt %, and a redox ratio in the range of 0.005-0.15, more preferably in the range of 0.005-010. The glass can be chemically tempered and used to provide a ballistic viewing cover for night vision goggles or scope. A method is provided to change a glass making process from making a high infrared absorbing lithium glass having FeO in the range of 0.02 to 0.04 wt % and a redox ratio in the range of 0.2 to 0.4 to the low infrared absorbing lithium glass by adding additional oxidizers to the batch materials. A second method is provided to change a glass making process from making a low infrared absorbing lithium glass to the high infrared absorbing lithium glass by adding additional reducers to the batch material. In one embodiment of the invention the oxidizer is CeO 2 . An embodiment of the invention covers a glass made according to the method.
1. A device for viewing radiated infrared energy, the device comprising:
a housing having at least one passageway, the passageway having a first open end and a second open end, a lens system for viewing radiated infrared energy and
a chemically tempered ballistic glass lens mounted adjacent to one end of the passageway, the ballistic glass lens comprising a first surface, an opposite second surface and a glass segment between the first and the second surfaces of the ballistic glass lens, the glass segment consisting essentially of a lithium base portion, a colorant portion, and an oxidizer,
Component
Range
the lithium base glass portion consisting essentially of:
SiO 2
60-63
wt %
Na 2 O
10-12
wt %
Li 2 O
4-5.5
wt %
Al 2 O 3
17-19
wt %
ZrO 2
3.5-5
wt %
(Al2O 3 + ZrO 2 )
21.5-24
wt %
the colorant portion consisting essentially of:
FeO
0.0005-0.015
wt %
Fe 2 O 3 (total iron)
50-1200
ppm;
a redox ratio of 0.005-0.15; and
the oxidizer consisting essentially of cerium oxide in the range of greater than 0 to 0.50 wt % and/or manganese oxide in the range of greater than 0 to 0.75 wt %
wherein the glass has a visible transmission of greater than 88%, an infrared transmission of greater than 85%, and an infrared viewing transmission of greater than 80%, wherein the spectral properties of the glass given above are reported at a glass thickness of 0.223 inch (5.7 millimeters), and the visible transmission is determined using CIE Standard Illuminant A with a 2° observer over a wavelength range of 380 to 780 nanometers; the infrared transmission is determined using Parry Moon air mass 2.0 direct solar irradiance data over a wavelength range of 800 to 2100 nm, and the infrared viewing transmission is determined using the relative spectral irradiance of CIE Standard Illuminant A and the response function of the viewing device over the wavelength range 400 to 930 nm.
2. The device according to claim 1 , wherein the lens has a visible transmission of greater than 88%, an infrared transmission of greater than 80%, and an infrared viewing transmission of greater than 80%, the transmissions are for a glass lens having a thickness 0.223 inch (5.7 millimeter).
3. The device according to claim 1 , wherein the FeO of the glass segment is in the range of 0.001-0.010 wt %.
4. The device according to claim 3 , wherein the redox ratio of the glass segment is in the range of 0.005 to 0.10.
5. The device according to claim 1 , wherein the oxidizer is cerium oxide in the range of 0.02 to 0.45 wt % or manganese oxide in the range of 0.02 to 0.50 wt %.
6. The device according to claim 1 , wherein Fe 2 O 3 (total iron) is in an amount with at least one of the following ranges 50-500 ppm; 50-350 ppm; 75-300 ppm; 100-250 ppm; 200-400 ppm; 300-600 ppm; 500-900 ppm; 700-1100 ppm; 900-1200 ppm; and 500-1200 ppm.
7. The device according to claim 1 , wherein the cerium oxide is in the range of 0.01 to 0.15 wt %.
8. The device according to claim 1 , wherein Fe 2 O 3 (total iron) is in the range of 50 to 300 ppm.
9. The device according to claim 1 , wherein the FeO is in the range of 0.001-0.010 wt %; the total iron is in the range of 50 to 300 ppm; the redox ratio is in the range of 0.005 to 0.10 and the oxidizer is cerium oxide in the range of 0.02 to 0.45 wt % or manganese oxide in the range of 0.02 to 0.50 wt %.
10. A laminated transparency comprising a plurality of chemically strengthened glass sheets and optionally plastic sheets laminated together by plastic interlayers, wherein at least one of the glass sheets has a glass composition consisting essentially of a lithium base portion, a colorant portion, and an oxidizer,
Component
Range
the lithium base glass portion consisting essentially of:
SiO 2
60-63
wt %
Na 2 O
10-12
wt %
Li 2 O
4-5.5
wt %
Al 2 O 3
17-19
wt %
ZrO 2
3.5-5
wt %
(Al2O 3 + ZrO 2 )
21.5-24
wt %
the colorant portion consisting essentially of:
FeO
0.0005-0.015
wt %
Fe 2 O 3 (total iron)
50-1200
ppm;
with a redox ratio of 0.005-0.15; and
the oxidizer consisting essentially of cerium oxide in the range of greater than 0 to 0.50 wt % and/or manganese oxide in the range of greater than 0 to 0.75 wt %
wherein the glass has a visible transmission of greater than 88%, an infrared transmission of greater than 85%, and an infrared viewing transmission of greater than 80%, wherein the spectral properties of the glass given above are reported at a glass thickness of 0.223 inch (5.7 millimeters), and the visible transmission is determined using CIE Standard Illuminant A with a 2° observer over a wavelength range of 380 to 780 nanometers; the infrared transmission is determined using Parry Moon air mass 2.0 direct solar irradiance data over a wavelength range of 800 to 2100 nm, and the infrared viewing transmission is determined using the relative spectral irradiance of CIE Standard Illuminant A and the response function of the viewing device over the wavelength range 400 to 930 nm.
11. The laminated transparency according to claim 10 , wherein the laminated transparency is selected from the group of aircraft windows, and land, air, space, on the water and below the water vehicle windows.
12. The laminated transparency according to claim 10 , wherein the window is a windshield.
13. The laminated transparency according to claim 10 , wherein Fe 2 O 3 (total iron) is in an amount with at least one of the following ranges 50-500 ppm; 50-350 ppm; 75-300 ppm; 100-250 ppm; 200-400 ppm; 300-600 ppm; 500-900 ppm; 700-1100 ppm; 900-1200 ppm; and 500-1200 ppm.