Boule oscillation patterns in methods of producing fused silica glass
AssigneeCorning Incorporated
InventorJohn E. Maxon
Life of this patent
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Abstract
Oscillation/rotation patterns for improving the off-axis homogeneity of fused silica boules are provided. The patterns reduce the optical effects of periodic off-axis striae by decreasing the ratio of .DELTA.n.sub.striae to .DELTA.z.sub.striae, where .DELTA.n.sub.striae is the average peak-to-valley magnitude of the striae and .DELTA.z.sub.striae is their average peak-to-peak period. The oscillation/rotation patterns have long repeat periods and cause soot-producing burners to trace out substantially spiral-shaped patterns on the surface of the boule.
Claims37
A method for forming a silica-containing body comprising:
- (a) providing a source of soot particles;
- (b) collecting the soot particles to form the body, said collection causing the thickness of the body to increase;
- and
- (c) providing relative oscillatory motion between the source and the body as the soot particles are collected, said oscillatory motion being orthogonal to the thickness of the body and having a repeat period;
- said collection and oscillation being performed so that the thickness of the body increases by at least about 0.15 mm during the repeat period.
A method for forming a silica-containing body comprising:
- (a) providing a source of soot particles;
- (b) collecting the soot particles to form the body, said collection causing the thickness of the body to increase;
- and
- (c) providing relative oscillatory motion between the source and the body as the soot particles are collected, said oscillatory motion being orthogonal to the thickness of the body and having a repeat period of at least about eight minutes.
A method for forming a silica-containing body comprising:
- (a) providing a source of soot particles;
- (b) collecting the soot particles to form the body, said soot particles being consolidated to form a viscous fluid as they are collected, said collection causing the thickness of the body to increase;
- and
- (c) rotating the body and providing relative oscillatory motion between the source and the body as the soot particles are collected, said oscillatory motion being orthogonal to the thickness of the body and said rotation and oscillatory motion being such that the projection of the source onto the body traces out a path which is substantially a spiral.
A method for reducing off-axis periodic striae in the index of refraction of a blank formed from a silica-containing body, said off-axis periodic striae having an average peak-to-valley magnitude .DELTA.n.sub.striae and an average peak-to-peak period .DELTA.z.sub.striae, said method comprising:
- (a) providing a source of soot particles;
- (b) collecting the soot particles to form the body, said collection causing the thickness of the body to increase;
- and
- (c) providing relative oscillatory motion between the source and the body as the soot particles are collected, said oscillatory motion being orthogonal to the thickness of the body and having a repeat period which is sufficiently long so that .DELTA.n.sub.striae /.DELTA.z.sub.striae for the blank is less than or equal to about 2.0.times.10.sup.-8 mm.sup.-1.
A fused silica blank which has:
- (a) a .DELTA.n.sub.striae /.DELTA.z.sub.striae value which is less than or equal to about 2.0.times.10.sup.-8 mm.sup.-1, where .DELTA.n.sub.striae and .DELTA.z.sub.striae are the average peak-to-valley magnitude and the average peak-to-peak period, respectively, of the blank's off-axis striae;
- and
- (b) a z-axis homogeneity .DELTA.n which is less than or equal to 1.0.times.10.sup.-6 for a blank size greater than or equal to 125 millimeters.
Dependencies are inferred from the claim text.