Method of making optical fibers utilizing thermophoretic deposition of glass precursor particulates

DETAILED DESCRIPTION 1.
Introduction The invention, in its most generic form, involves increasing the deposition efficiency of glass precursor particulate material (usually in the range of 0.
1-1.
0 microns in diameter) during the fiber fabrication process by increasing the effect of the thermophoretic forces which direct the particulate material to the appropriate substrate.
The term thermophoretic forces, as used in this specification, denotes the thermal forces acting on a particle as a result of the temperature gradient associated with the surrounding environment.
The effect of this temperature gradient on a given particle may be understood by considering the molecular forces impinging on the particle.
Those molecules which strike the particle from the high temperature side impart a greater impulse to the particle than those molecules which strike the particle from the low temperature side.
In addition, the practitioner skilled in the art will appreciate that concomitant radiation effects may augment these "molecular" forces.
As a result of these and similar effects, the particle "feels" a net force directing it from the hotter temperature zone to the cooler temperature zone.
This is the "theromophoretic" effect to which this specification has reference.
The invention envisions a thermophoretic force sufficiently large to influence the vector velocity of the particulate material formed.
According to the teachings of this invention, specific means are used to enhance the thermophoretic forces, over and above the means which are concomitant to the normal deposition process encountered in standard fiber fabrication techniques.
It should be carefully noted that in most fiber fabrication processes thermophoretic forces are involved in the particulate deposition--albeit without the intentional design of the practitioner--to yield particulate deposition.
Consequently, applicants are not the first to suggest a deposition configuration involving thermophoretic forces.
However, they are the first to appreciate the presence of such forces and their importance in particulate deposition during fiber fabrication