Melt fixture and a sapphire component

Abstract

Various single crystals are disclosed including sapphire. The single crystals have desirable geometric properties, including a width not less than about 15 cm and the thickness is not less than about 0.5 cm. The single crystal may also have other features, such as a maximum thickness variation, and as-formed crystals may have a generally symmetrical neck portion, particularly related to the transition from the neck to the main body of the crystal. Methods and for forming such crystals and an apparatus for carrying out the methods are disclosed as well.

What is claimed is: 
     
         1 . A melt fixture comprising:
 a crucible;   a die open to and extending along a length of the crucible; and   a plurality of thermal shields overlying the crucible and adjacent to the die, the thermal shields having a stepped configuration.   
     
     
         2 . The melt fixture of  claim 1 , wherein thermal shields include a first shield set positioned along a first lateral side of the die, and a second shield set positioned along an opposite, second lateral side the die. 
     
     
         3 . The melt fixture of  claim 2 , wherein each of the first and second shield sets is generally symmetrical about a vertical central axis corresponding to midpoint of the die. 
     
     
         4 . The melt fixture of  claim 1 , further comprising an afterheater disposed above the die and configured to receive an as-formed crystal sheet, wherein the afterheater has a lower compartment and an upper compartment separated from each other by an isolation structure. 
     
     
         5 . The melt fixture of  claim 1 , wherein thermal shields are substantially parallel to one another. 
     
     
         6 . The melt fixture of  claim 5 , further comprising shield pins to hold the thermal shields in place. 
     
     
         7 . The melt fixture of  claim 1 , wherein the thermal shields provide a static temperature gradient along the die. 
     
     
         8 . The melt fixture of  claim 7 , wherein the thermal shields provide a temperature profile along the length of the die such that the temperature profile has a maximum temperature at about a midpoint of the die. 
     
     
         9 . The melt fixture of  claim 1 , wherein the die has an opening with a length that is not less than about 28 cm. 
     
     
         10 . The melt fixture of  claim 9 , wherein the opening of the die has a width that is not less than about 0.5 cm. 
     
     
         11 . The melt fixture of  claim 10 , wherein the length of the opening is not less than about 30 cm. 
     
     
         12 . The melt fixture of  claim 1 , further comprising an afterheater having a lower compartment and an upper compartment separated from each other by an isolation structure. 
     
     
         13 . The method of  claim 12 , wherein the isolation structure comprises isolation doors, between the lower compartment and the upper compartment. 
     
     
         14 . A sapphire component made by the method comprising machining a sapphire single crystal having a length, a width and a thickness, wherein the length>width>thickness, the width is not less than 28 cm, and the thickness is not less than 0.5 cm into the sapphire component. 
     
     
         15 . The sapphire component of  claim 14 , wherein the sapphire component comprises an optical window. 
     
     
         16 . The sapphire component of  claim 15 , wherein the optical window has a geometric configuration for an infrared and laser guidance system, a military sensing and targeting system, or an infrared and visible wavelength vision system 
     
     
         17 . An infrared and laser guidance system, a military sensing and targeting system or an infrared and visible wavelength vision system comprising the sapphire component of  claim 14 . 
     
     
         18 . The sapphire component of  claim 14 , wherein the sapphire single crystal is transparent in the infrared and visible wavelength spectrums. 
     
     
         19 . The method of  claim 1 , wherein machining the sapphire single crystal comprises grinding, lapping, or polishing the sapphire single crystal. 
     
     
         20 . The method of  claim 1 , wherein machining the sapphire single crystal comprises removing bulk material from the sapphire single crystal.