Multi-layer burner module, adapter, and assembly therefor

The present invention relates to burner devices, and, more particularly, to burner assemblies, modules and adapters for producing an inorganic soot.

It is known to form various articles, such as crucibles, tubing, lenses, and optical waveguides, by reacting a precursor in the flame of a burner to produce a soot and then depositing the soot on a receptor surface. This process is particularly useful for the formation of optical waveguide preforms made from doped and undoped silica soot, including planar waveguides and waveguide fibers.

The waveguide formation process generally involves reacting a silicon-containing precursor in a burner flame generated by a combustible gas, such as a mixture of methane and oxygen, and depositing the silica soot on an appropriately shaped receptor surface. In this process, silicon-containing materials typically are vaporized at a location remote from the burner. The vaporized raw materials are transported to the burner by a carrier gas. There, they are volatilized and hydrolyzed to produce soot particles. The soot particles then collect on the receptor surface. The receptor surface may be a flat substrate in the case of planar waveguide fabrication, a rotating starting rod (bait tube) in the case of vapor axial deposition (VAD) for waveguide fiber fabrication, or a rotating mandrel in the case of outside vapor deposition (OVD) for waveguide fiber fabrication.

Numerous burner designs have been developed for use in vapor delivery precursor processes, and at least one liquid delivery precursor process has been contemplated. Whether the precursor is delivered to the burner in vapor form or liquid form, it is important that the burner receives a distributed, even stream of precursor. This consideration is particularly important during waveguide manufacture to form accurate refractive index profiles.

According to embodiments of the present invention, a burner module for delivering a flow of chemical reactants to a combustion site of a chemical vapor deposition process includes a plurality of substantially planar layers. The burner modules are generally rectangular is shape such that they may be arranged in side-by-side orientation. The substantially planar layers of the burner module are arranged in a generally parallel and fixed relationship and define an inlet, an outlet and a passage fluidly connecting the inlet and the outlet. At least one of the layers is a distribution layer having a plurality of apertures therethrough and fluidly communicating with the passage. The plurality of apertures collectively define a non-uniform pattern arranged and configured to improve the uniformity of a flow out through the outlet.

According to further embodiments of the present invention, a burner mounting adapter for use with a manifold having a mount surface and first and second fluid supply openings in the mount surface and distributed at different locations along a length of the manifold includes an adapter body. A first inlet aperture, a first outlet aperture and a first connecting passage fluidly connecting the first inlet and outlet apertures are defined in the adapter body. A second inlet aperture, a second outlet aperture and a second connecting passage fluidly connecting the second inlet and outlet apertures are defined in the adapter body. The first and second inlet apertures are arranged and configured to align with the first and second fluid supply openings, respectively, when the burner mounting adapter is mounted on the mount surface of the manifold. The first and second passages extend transversely of the manifold length when the burner mounting adapter is mounted on the mount surface of the manifold. Thus, it should be recognized that the burner mounting adapter connects the macro scale of the manifold to the micro scale of the burner face.

According to further embodiments of the present invention, a burner module for use with a manifold having a mount surface and first and second fluid supply openings in the mount surface and distributed at different locations along a length of the manifold includes a burner mounting adapter. The burner mounting adapter includes an adapter body. A first inlet aperture, a first outlet aperture and a first connecting passage fluidly connecting the first inlet and outlet apertures are defined in the adapter body. A second inlet aperture, a second outlet aperture and a second connecting passage fluidly connecting the second inlet and outlet apertures are defined in the adapter body. The first and second inlet apertures are arranged and configured to align with the first and second fluid supply openings, respectively, when the burner mounting adapter is mounted on the mount surface of the manifold. The first and second passages extend transversely of the manifold length when the burner mounting adapter is mounted on the mount surface of the manifold. A burner face layer overlies the adapter body and the distribution layers. The burner face layer includes at least first and second burner apertures fluidly communicating with the first and second outlet apertures of the adapter body, respectively.

According to further embodiments of the present invention, a burner assembly for delivering a flow of chemical reactants to a combustion site of a chemical vapor deposition process includes a manifold and a burner module. The manifold includes a mount surface with first and second fluid supply openings distributed at different locations along a length of the manifold. The burner module includes a burner mounting adapter including an adapter body. A first inlet aperture, a first outlet aperture and a first connecting passage fluidly connecting the first inlet and outlet apertures are defined in the adapter body. A second inlet aperture, a second outlet aperture and a second connecting passage fluidly connecting the second inlet and outlet apertures are defined in the adapter body. The first and second inlet apertures are arranged and configured to align with the first and second fluid supply openings, respectively, when the burner mounting adapter is mounted on the mount surface of the manifold. The first and second passages extend transversely of the manifold length when the burner mounting adapter is mounted on the mount surface of the manifold. A burner face layer overlies the adapter body. The burner face layer includes at least first and second burner apertures fluidly communicating with the first and second outlet apertures of the adapter body, respectively.

According to further embodiments of the present invention, a burner module for delivering a flow of chemical reactants to a combustion site of a chemical vapor deposition process includes a burner face layer and a reflective layer covering the burner face layer.

Further features, advantages and details of the present invention will be appreciated by those of ordinary skill in the art from a reading of the Figs. and the detailed description of the preferred embodiments which follow, such description being merely illustrative of the present invention.

FIG. 1 is a perspective view of a burner assembly according to embodiments of the present invention;

FIG. 2 is a partial exploded, perspective view of the burner assembly of FIG. 1;

FIG. 3 is a top plan view of the burner assembly of FIG. 1;

FIG. 4 is an exploded, perspective view of the burner assembly of FIG. 1;

FIG. 5 is a side view of the burner assembly of FIG. 1;

FIG. 6 is a top plan view of a manifold forming a part of the burner assembly of FIG. 1;

FIG. 7 is a top plan view of a manifold interface adapter layer forming a part of the burner assembly of FIG. 1;

FIG. 8 is a top plan view of a convergence adapter layer forming a part of the burner assembly of FIG. 1;

FIG. 9 is a top plan view of a burner interface layer forming a part of the burner assembly of FIG. 1;

FIG. 10 is a top plan view of an adapter interface layer forming a part of the burner assembly of FIG. 1;

FIG. 11 is a top plan view of a plenum layer forming a part of the burner assembly of FIG. 1;

FIG. 12 is a top plan view of a distribution layer forming a part of the burner assembly of FIG. 1 with enlarged details;

FIG. 13 is a top plan view of a further plenum layer forming a part of the burner assembly of FIG. 1;

FIG. 14 is a top plan view of a further distribution layer forming a part of the burner assembly of FIG. 1 with enlarged details;

FIG. 15 is a top plan view of a burner face layer forming a part of the burner assembly of FIG. 1;

FIG. 16 is a cross-sectional view of the burner assembly of FIG. 1 taken along the line 16 — 16 of FIG. 3;

FIG. 17 is a cross-sectional view of the burner assembly of FIG. 1 taken along the line 17 — 17 of FIG. 5;

FIG. 18 is a cross-sectional view of the burner assembly of FIG. 1 taken along the line 18 — 18 of FIG. 3;

FIG. 19 is a cross-sectional view of the burner assembly of FIG. 1 taken along the line 19 — 19 of FIG. 5;

FIG. 20 is a cross-sectional view of the burner assembly of FIG. 1 taken along the line 20 — 20 of FIG. 3;

FIG. 21 is a cross-sectional view of the burner assembly of FIG. 1 taken along the line 21 — 21 of FIG. 5;

FIG. 22 is a cross-sectional view of the burner assembly of FIG. 1 taken along the line 22 — 22 of FIG. 3;

FIG. 23 is a cross-sectional view of the burner assembly of FIG. 1 taken along the line 23 — 23 of FIG. 5;

FIG. 24 is a cross-sectional view of the burner assembly of FIG. 1 taken along the line 24 — 24 of FIG. 3;

FIG. 25 is a cross-sectional view of the burner assembly of FIG. 1 taken along the line 25 — 25 of FIG. 5;

FIG. 26 is a schematic view of a burner system including the burner assembly of FIG. 1;

FIG. 27 is a top plan view of a distribution layer according to alternative embodiments of the present invention with enlarged details;

FIG. 28 is a top plan view of a distribution layer according to further alternative embodiments of the present invention with enlarged details;

FIG. 29 is a top plan view of a distribution layer according to further alternative embodiments of the present invention with enlarged details; and

FIG. 30 is a top plan view of a distribution layer according to further alternative embodiments of the present invention with enlarged details.

The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

With reference to FIGS. 1-5 and 26 , a burner assembly 10 according to preferred embodiments of the present invention is shown therein. The burner assembly 10 includes a block-shaped manifold 100 and a plurality of rectangular-shaped burner modules 50 mounted on the surface of the manifold 100 by means of fasteners (preferably threaded bolts) 40 . Each module 50 includes a mounting adapter 200 and a burner 300 . With reference to FIG. 26, the burner assembly 10 may form a part of a burner system 11 operable to provide a flame 20 which may be used to apply a soot deposit 35 onto a bait rod 30 or other suitable substrate (e.g., a glass core cane). In particular, the burner assembly 10 may be used to form a soot preform 33 which may be subsequently consolidated to form a glass preform, from which an optical waveguide fiber may be drawn.

Turning to the manifold 100 in greater detail, the manifold 100 is preferably formed from a unitary block of metal (e.g., steel or aluminum), ceramic or other suitable material. However, the manifold 100 may be assembled from multiple discrete members. The manifold 100 has a top face 102 and opposed side faces 104 and 106 . For the purposes of description, the manifold 100 has a lengthwise axis A—A (FIGS. 1 and 3 ), a lateral axis B—B (see FIGS. 1 and 3 ), and a vertical axis C—C (see FIG. 5 ); however, it will be appreciated that the manifold 100 and the burner assembly 10 , although preferable to be mounted as such, may be positioned such that the axis C—C is not vertically oriented. The manifold 100 as illustrated is adapted to hold up to five modules 50 . Many manifolds may be mounted adjacent to each other along the axis A—A such that large soot preforms may be manufactured. As shown in FIG. 2, a pair of opposed, threaded mounting bores 108 are formed in the top face 102 for each module 50 . However, as will be appreciated from the description herein, the manifold 100 may be modified to hold more or fewer of the modules 50 . Additionally, as discussed below, fewer of the modules 50 may be mounted on the manifold 100 than the manifold 100 is adapted to hold.

As shown in FIGS. 1 and 5, five sets of inlet openings 110 , 120 , 130 , 140 , 150 are formed in the side face 104 and are distributed along the length of the manifold 100 . The set 110 includes inlet openings 110 A, 110 B, 110 C, 110 D, 110 E spaced apart along the height and distributed along the length of the manifold 100 . Similarly, the sets 120 , 130 , 140 , and 150 include inlet openings 120 A- 120 E, 130 A- 130 E, 140 A- 140 E, and 150 A- 150 E, respectively, which are arranged in the same manner as the inlet openings 110 A- 110 E.

As shown in FIG. 6, five sets of supply openings 112 , 122 , 132 , 142 , 152 are formed in the top face 102 and are distributed along the length of the manifold 100 . The set 112 includes supply openings 112 A, 112 B, 112 C, 112 D, 112 E spaced apart along the height and distributed along the length of the manifold 100 . Similarly, the sets 122 , 132 , 142 , and 152 include supply openings 122 A- 122 E, 132 A- 132 E, 142 A- 142 E, and 152 A- 152 E, respectively, which are arranged in the same manner as the supply openings 112 A- 112 E. The supply openings are preferably spaced apart from between about 5 mm and 19 mm from the adjacent supply openings of the same set. High temperature elastomer O-rings, such as made from Viton, may be provided about each supply opening.

As shown in FIGS. 16-25, five sets of passages 114 A-E, 124 A-E, 134 A-E, 144 A-E, 154 A-E are formed in the manifold 100 and extend laterally and vertically through the manifold 100 to fluidly connect the sets of inlet openings 110 , 120 , 130 , 140 , and 150 to the sets of supply openings 112 , 122 , 132 , 142 , and 152 , respectively. More particularly, each set of passages includes five passages, each joining one of the inlet openings with a respective one of the supply openings. For example, one set includes passages 114 A, 114 B, 114 C, 114 D, and 114 E connecting the openings 110 A and 112 A, the openings 110 B and 112 B, the openings 110 C and 112 C, the openings 110 D and 112 D, and the openings 110 E and 112 E, respectively. Similarly, the remaining four sets of passages each include five passages 124 A- 124 E, 134 A- 134 E, 144 A- 144 E, and 154 A- 154 E, respectively. In similar fashion to the passages 114 A- 114 E, the passages 124 A- 124 E connect each of the inlet openings 120 A- 120 E to the corresponding supply openings 122 A- 122 E, the passages 134 A- 134 E connect each of the inlet openings 130 A- 130 E to the corresponding supply openings 132 A- 132 E, the passages 144 A- 144 E connect each of the inlet openings 140 A- 140 E to the corresponding supply openings 142 A- 142 E, and the passages 154 A- 154 E connect each of the inlet openings 150 A- 150 E to the corresponding supply openings 152 A- 152 E.

As best illustrated in FIGS. 1 and 2, the modules 50 may be substantially identically formed. Accordingly, only one of the modules 50 will be described in detail hereinbelow. As noted above, each module 50 includes an adapter 200 and a burner 300 .

With reference to FIGS. 4 and 7 - 9 , the mounting adapter 200 includes a manifold interface adapter layer 210 (FIGS. 4 and 7 ), a convergence adapter layer 230 (FIGS. 4 and 8 ), and a burner interface layer 240 (FIGS. 4 and 9 ). The layers 210 , 230 , 240 are stacked as illustrated. In the manufacturing process, the layers 210 , 230 , 240 are preferably fused or anodically bonded to one another.

With reference to FIG. 7, the adapter layer 210 includes apertures 212 A, 212 B, 212 C, 212 D, 212 E and 218 extending fully through its thickness. The layer 210 is preferably between about 2 mm and 4 mm thick. The layer 210 is mounted on the top face 102 of the manifold 100 such that the apertures 212 A, 212 B, 212 C, 212 D, 212 E align with the supply openings 112 A, 112 B, 112 C, 112 D, 112 E (FIG. 6 ), respectively, to provide fluid communication therethrough. The openings 218 align with the bores 108 and are adapted to receive the bolts 40 therethrough. Preferably, the layer 210 is formed of glass, silicon, silicon carbide, borosilicate glass, polycrystalline silica, ceramic, plastic, or photodefinable metal. More preferably, the layer 210 is formed of PYREX® material manufactured by Corning Incorporated of Corning, N.Y.

With reference to FIG. 8, the adapter layer 230 of mounting adapter 200 (FIGS. 1, 2 ) includes laterally extending slots 232 A, 232 B, 232 D, 232 E, an aperture 232 C and apertures 238 extending fully through its thickness. The layer 230 preferably has a thickness of between about 2 mm and 4 mm. The slots 232 A, 232 B, 232 D, 232 E each extend transversely (i.e., along the direction parallel to the lateral axis B—B) along the length of the adapter layer 230 . The layer 230 is mounted on the layer 210 such that the apertures 212 A align and connect with the slots 232 A adjacent the outer ends thereof (see FIG. 16 ), the apertures 212 B align and connect with the slots 232 B adjacent the outer ends thereof (see FIG. 18 ), the aperture 212 C aligns and connects with the aperture 232 C (see FIG. 20 ), the apertures 212 D align and connect with the apertures 232 D adjacent the outer ends thereof (see FIG. 22 ), and the apertures 212 E align and connect with the apertures 232 E adjacent the outer ends thereof (see FIG. 24 ). Preferably, the slots 232 A each have a length of between about 14 mm and 15 mm, the slots 232 B each have a length of between about 20 mm and 21 mm, the slots 232 D each have a length of between about 8 mm and 9 mm, and the slots 232 E each have a length of between about 27 mm and 28 mm. Preferably, the layer 230 is formed of glass, silicon, silicon carbide, borosilicate glass, polycrystalline silica, ceramic, plastic, or photodefinable metal. More preferably, the layer 230 is formed of silicon.

With reference to FIG. 9, the adapter layer 240 includes apertures 242 A, 242 B, 242 C, 242 D, 242 E and 248 extending fully through its thickness. Preferably, the layer 240 has a thickness of between about 2 mm and 4 mm. The layer 240 is mounted on the layer 230 such that the apertures 242 A mate with the slots 232 A adjacent the inner ends thereof (see FIG. 16 ), the apertures 242 B mate with the slots 232 B adjacent the inner ends thereof (see FIG. 18 ), the aperture 242 C (see FIG. 20) mates with the aperture 232 C, the apertures 242 D mate with the slots 232 D adjacent the inner ends thereof (see FIG. 22 ), and the apertures 242 E mate with the slots 232 E adjacent the inner ends thereof (see FIG. 24 ). The diameters and shapes of the apertures 242 A- 242 E are substantially the same as the diameters and shapes of the apertures 312 A- 312 E discussed below. The apertures 242 A- 242 E may be smaller than and/or differently shaped than the apertures 212 A- 212 E. Preferably, the layer 240 is formed of glass, silicon, silicon carbide, borosilicate glass, polycrystalline silica, ceramic, plastic, or photodefinable metal. More preferably, the layer 240 is formed of PYREX®.

Turning to the burner 300 in more detail as shown in FIG. 4, the burner 300 includes an adapter interface layer 310 , a plenum layer 320 , a distribution layer 330 , a plenum layer 340 , a distribution layer 350 , a plenum layer 360 , and a burner face layer 370 . The layers 310 , 320 , 330 , 340 , 350 , 360 , 370 are stacked similarly as is illustrated for the adapter 200 . The layers 310 , 320 , 330 , 340 , 350 , 360 , 370 are preferably fused or anodically bonded to one another and to the adapter layer 240 .

With reference to FIG. 10, the interface layer 310 includes apertures 312 A, 312 B, 312 C, 312 D, 312 E extending fully through the thickness thereof. Preferably, the layer 310 has a thickness of between about 400 microns and 500 microns. The layer 310 is mounted on the adapter layer 240 such that the apertures 312 A, 312 B, 312 C, 312 D, 312 E align and seal with the apertures 240 A, 240 B, 240 C, 240 D, 240 E, respectively, to provide a passage and fluid communication therethrough. Preferably, the layer 310 is formed of glass, silicon, silicon carbide, borosilicate glass, polycrystalline silica, ceramic, plastic, or photodefinable metal. More preferably, the layer 310 is formed of silicon.

With reference to FIG. 11, the plenum layer 320 includes longitudinally extending slots 322 A, 322 B, 322 C, 322 D, 322 E extending fully through the thickness thereof. Preferably, the thickness of the layer 320 is between about 1 and 5 mm, and more preferably, between about 2 and 4 mm. The layer 320 is mounted to the layer 310 such that the slots 322 A, 322 B, 322 C, 322 D, 322 E mate and align with the apertures 312 A, 312 B, 312 C, 312 D, 312 E, respectively. Preferably, each of the apertures 312 A, 312 B, 312 C, 312 D, 312 E enters the respective slot at locations along each slot 322 A, 322 B, 322 C, 322 D, 322 E. Preferably, each slot 322 A- 322 E has a width (i.e., extending parallel to the lateral axis B—B) of between about 650 and 1000 microns. The lateral distance between adjacent ones of the slots 322 A- 322 E is preferably between about 100 and 1000 microns, and more preferably, between about 350 and 500 microns. Preferably, the layer 320 is formed of glass, silicon, silicon carbide, borosilicate glass, polycrystalline silica, ceramic, plastic, or photodefinable metal. More preferably, the layer 320 is formed of PYREX®.

With reference to FIG. 12, a first distribution layer 330 includes sets of apertures 332 A, 332 B, 332 C, 332 D, 332 E. Each set of apertures 332 A, 332 B, 332 C, 332 D, 332 E includes a plurality of apertures defining a selected pattern. Each set 332 A, 332 B, 332 C, 332 D, 332 E in this embodiment is preferably substantially identical and includes a uniform array of apertures. The apertures 334 E (forming a part of the set 332 E) and the apertures 334 B (forming a part of the set 332 B) as shown in the enlargement of FIG. 12 are exemplary. Preferably, the apertures of the sets (including the apertures 334 B and 334 E) are circular and each have a diameter of between about 5 and 300 microns, and more preferably, between about 50 and 200 microns. Preferably, adjacent ones of the apertures are spaced apart from one another a distance of between about 75 microns and 80 microns. Preferably, the thickness of the distribution layer 330 is between about 300 and 700 microns, and more preferably, between about 400 and 550 microns. Preferably, the layer 330 is formed of glass, silicon, silicon carbide, borosilicate glass, polycrystalline silica, ceramic, plastic, or photodefinable metal. More preferably, the layer 330 is formed of silicon.

With reference to FIG. 13, the plenum layer 340 includes longitudinally extending slots 342 A, 342 B, 342 C, 342 D, 342 E extending through the thickness thereof. Preferably, the layer 340 has a thickness of between about 1 and 5 mm, and more preferably, between about 2 and 4 mm. The layer 340 is mounted on the layer 330 such that the slots 342 A, 342 B, 342 C, 342 D, 342 E mate and align with the sets of apertures 332 A, 332 B, 332 C, 332 D, 332 E, respectively. Preferably, all the sets of apertures 332 A, 332 B, 332 C, 332 D, 332 E, empty into the slots 342 A, 342 B, 342 C, 342 D, 342 E in operation. Preferably, each slot 342 A- 342 E has a width of between about 650 and 1000 microns. The lateral distance between adjacent ones of the slots 342 A- 342 E is preferably between about 100 and 1000 microns, and more preferably, between about 350 and 500 microns. Preferably, the layer 340 is formed of glass, silicon, silicon carbide, borosilicate glass, polycrystalline silica, ceramic, plastic, or photodefinable metal. More preferably, the layer 340 is formed of PYREX®.

With reference to FIG. 14, a second distribution layer 350 includes sets of apertures 352 A, 352 B, 352 C, 352 D, 352 E. Each set of apertures 352 A, 352 B, 352 C, 352 D, 352 E includes a plurality of apertures defining a selected pattern. In this embodiment, each set 352 A, 352 B, 352 C, 352 D, 352 E is preferably substantially identical and includes a uniform array of apertures. The apertures 354 E (forming parts of the set 352 E) and the apertures 354 B (forming parts of the set 352 B) as shown in the enlargements of FIG. 14 are exemplary. Preferably, the apertures of the sets 352 A, 352 B, 352 C, 352 D, 352 E (including the apertures 354 B and 354 E) are preferably circular and each have a diameter of between about 5 and 300 microns, and more preferably, between about 50 and 200 microns. Preferably, the average diameter of the apertures of the distribution layer 350 is less than the average diameter of the apertures of the distribution layer 330 . Preferably, adjacent ones of the apertures of the sets 352 A- 352 E are spaced apart from one another a distance of between about 70 and 80 microns. Preferably, the thickness of the layer 350 is between about 300 and 700 microns, and more preferably, between about 400 and 550 microns. Preferably, the layer 350 is formed of glass, silicon, silicon carbide, borosilicate glass, polycrystalline silica, ceramic, plastic, or photodefinable metal. More preferably, the layer 350 is formed of silicon.

With reference to FIG. 13, the plenum layer 360 is substantially identical to the layer 340 . The longitudinally extending slots of the layer 360 correspond to the longitudinally extending slots 342 A, 342 B, 342 C, 342 D, 342 E and overlie the sets of apertures 352 A, 352 B, 352 C, 352 D, 352 E, respectively, of the layer 350 .

With reference to FIG. 15, the burner face layer 370 includes rows 372 A, 372 B, 372 C, 372 D, 372 E of apertures. More particularly, each of the rows 372 A includes a plurality of apertures 374 A, each of the rows 372 B includes a plurality of apertures 374 B, the row 372 C includes a plurality of apertures 372 C, each of the rows 372 D includes a plurality of apertures 374 D, and each of the rows 372 E includes a plurality of apertures 374 E. The apertures 374 A, 374 B, 374 C, 374 D, 374 E are preferably circular as illustrated. Preferably, the diameters of the apertures 374 A, 374 B, 374 C, 374 D, 374 E are in the range of between about 100 and 2000 microns, and more preferably, between about 300 and 1000 microns. The diameters may be different in different rows as is illustrated. According to some embodiments, the diameters of the apertures 374 A- 374 E are smaller than the diameters of apertures of the distribution layers 330 , 350 along the same flow path. Preferably, adjacent ones of the apertures 374 A, 374 B, 374 C, 374 D, 374 E are spaced apart from adjacent apertures in the same row by a distance of between about 164 and 342 microns. Preferably, the apertures 374 A, 374 B, 374 C, 374 D, 374 E are spaced apart from apertures in adjacent rows by a distance of between about 675 and 750 microns. The burner face layer 370 is mounted on the layer 360 such that the rows 372 A, 372 B, 372 C, 372 D, 372 E overlie the slots of the layer 360 corresponding to the slots 342 A, 342 B, 342 C, 342 D, 342 E, respectively.

The adapter 200 includes a pair of opposed mounting portions or tabs 202 (see FIGS. 1, 4 and 20 ) extending laterally (i.e., transversely to the length of the manifold 100 ) beyond the burner 300 . The tabs 202 each include portions of the layers 210 , 230 , 240 and include the apertures 218 , 238 , 248 (FIGS. 7 - 9 ). Preferably, the tabs 202 extend laterally beyond the burner 300 a distance W 3 (FIG. 3) of between about 20 and 30 mm; more preferably between about 25 and 27 mm. The module 50 may be fastened to the top face 102 of the manifold by inserting the bolts 40 through the tabs 202 as illustrated in FIG. 1 . In this manner, the tabs 202 provide a secure and convenient means for attaching the module 50 to the top face 102 of the manifold 100 .

While the adapter 200 and the burner 300 have each been illustrated and described having a certain number of layers, additional layers may be provided. For example, the burner 300 may include additional distribution layers (i.e., formed similarly to the distribution layers 330 , 350 ) and/or additional plenum layers (i.e., formed similarly to the plenum layers 320 , 340 , 360 ). Preferably, any additional distribution layers are alternatingly interleaved with one or more additional plenum layers.

The passages of the manifold 100 and the slots and apertures of the adapter 200 and the burner 300 provide fluid flow paths (gas or liquid) from the inlet openings (e.g., the openings 110 A, 110 B, 110 C, 110 D, 110 E shown in FIG. 5) to the burner face layers 370 (FIG. 4) of the burner modules 50 . Each of the flow paths is fluidly isolated from the others. The passages and flow paths associated with each of the burner modules 50 and the sets 110 , 120 , 130 , 140 , 150 are substantially identical except for their locations along the length of the manifold 100 ; accordingly, the passages and flow paths associated with the set 110 and the left endmost burner module 50 (as viewed in FIG. 5) are exemplary and will be described hereinafter.

With reference to FIG. 26, supplies 70 A, 70 B, 70 C, 70 D, 70 E of burner fluids are fluidly connected to the inlet openings 110 A, 110 B, 110 C, 110 D, 110 E, respectively. The burner fluids may include process materials such as glass precursors, combustion fuels, carriers and facilitators. The burner fluids may be supplied as gases and/or liquids. Each fluid supply may be pressurized by suitable means. For example, one or more of the fluids may be supplied from a pre-pressurized vessel regulated using a regulator and/or a mass flow controller and/or using a pump, bubbler or vaporizer. Preferably, each supply is pressurized at the respective inlet opening 110 A, 110 B, 110 C, 110 D, 110 E to a pressure of between about 10 and 100 psi gage.

Burner fluid supplies may also be fluidly connected to each of the sets of inlet openings 120 , 130 , 140 , 150 for which a corresponding module 50 is mounted on the manifold 100 . For clarity, these connections are not illustrated in FIG. 26 .

As discussed in more detail below, the fluid supplied to the inlet 110 A will exit the burner assembly 10 from the burner face layer apertures 374 A, the fluid supplied to the inlet 110 B will exit through the apertures 374 B, the fluid supplied to the inlet 110 C will exit through the apertures 374 C, the fluid supplied to the inlet 110 D will exit through the apertures 374 D, and the fluid supplied to the inlet 110 E will exit through the apertures 374 E. The burner fluids preferably include O 2 , N 2 , CH 4 , H 2 , CO, SiCl 4 , GeCl 4 , OMCTS, CF 4 , SF 6 , SiF 4 , POCl 3 , ER(FOD), AlCl 3 , and/or TICS. According to some preferred embodiments, the fluid supplied to the inlet 110 A is a CH 4 /O 2 premix, the fluid supplied to the inlet 110 B is O 2 , the fluid supplied to the inlet 110 C is SiCl 4 , GeCl 4 , and O 2 , the fluid supplied to the inlet 110 D is O 2 , and the fluid supplied to the inlet 110 E is O 2 or, optionally, nothing.

With reference to FIGS. 7-16 and 17 , the fluid supplied to the inlet 110 A flows through the passage 114 A, the supply openings 112 A, the apertures 212 A and into the transverse slots 230 A. The slots 230 A direct the fluid flow inwardly (i.e., convergently) to the apertures 242 A. The fluid flows through the apertures 242 A, through the apertures 312 A and into the longitudinal slots 322 A. The slots 322 A serve as plenums from which the fluid then flows into and through the respective sets of apertures 332 A. The fluid exiting the apertures 332 A then flows into the slots 340 A (which, likewise, serve as plenums), through the respective sets of apertures 252 A and into the longitudinal slots 362 A (which, likewise, serve as plenums). From the slots 362 A, the fluid finally flows out of the burner assembly 10 through respective ones of the rows of apertures 372 A of the burner face layer 370 .

In the foregoing manner, the flow of the burner fluid introduced at the inlet 110 A may be supplied to the burner face layer 370 without requiring special accommodation. The transverse slots 232 A allow the use of relatively widely spaced apart supply openings 112 A on the top face 102 of the manifold 100 while providing relatively closely spaced burner face apertures 372 A. Accordingly, the openings 112 A may be formed using conventional techniques while nonetheless providing a flame of the desired, relatively narrow width.

The construction of the burner assembly 10 as well as the configurations of the burner modules 50 may allow for convenient and selective shaping of the profile of the overall soot flame 21 (see FIG. 26 ). The length of the soot flame 21 may be adjusted by mounting more or fewer of the modules 50 on the manifold 100 . The profile of the flame 21 may also be adjusted by mounting modules 50 of different configurations on the manifold 100 . For example, it may be desirable to provide modules 50 adapted to provide larger flames 20 at the outer ends of the manifold 100 to provide a more uniform flame 21 along the full length of the burner assembly 10 . The bolts 40 and tabs 202 may allow for secure, convenient, non-destructive, repeatable removal and remounting of the modules 50 .

Moreover, the flow of the burner fluid introduced at the inlet 110 A may be supplied to the burner face layer 370 in an evenly distributed manner. The plenums provided by the longitudinal slots 322 A, 340 A, 360 A and the patterned sets of apertures 332 A, 352 A, as well as the rows of apertures 372 A, serve to equalize the flow of the fluid along the length of the burner module 50 so that the rate and pressure of the flow from the apertures 372 A is more uniform. As a result, a more uniform flame and distribution of glass precursors may be provided.

With reference to FIGS. 1-15, 18 and 19 , the pressurized fluid supplied to the inlet 110 B is directed to the rows of apertures 372 B and conditioned or distributed in substantially the same manner as described above with respect to the pressurized fluid supplied to the inlet 110 A. More particularly, the fluid supplied to the inlet 110 B will flow through the passages 114 B, the openings 112 B, the apertures 212 B, the transverse slots 232 B, the apertures 242 B, the apertures 312 B, the longitudinal slots 322 B, the sets of apertures 332 B, the longitudinal slots 342 B, the sets of apertures 352 B, the longitudinal slots of the layer 360 corresponding to the slots 342 B, and the rows of apertures 372 B.

With reference to FIGS. 7-15, 20 and 21 , the pressurized fluid supplied to the inlet 110 C is directed to the rows of apertures 372 C and conditioned or distributed in substantially the same manner as described above with respect to the pressurized fluid supplied to the inlet 110 A. More particularly, the fluid supplied to the inlet 110 C will flow through the passage 114 C, the opening 112 C, the aperture 212 C, the aperture 232 C, the aperture 242 C, the aperture 312 C, the longitudinal slot 322 C, the set of apertures 332 C, the longitudinal slot 342 C, the set of apertures 352 C, the longitudinal slot of the layer 360 corresponding to the slot 342 C, and the row of apertures 372 C.

With reference to FIGS. 7-15, 22 and 23 , the pressurized fluid supplied to the inlet 110 D is directed to the rows of apertures 372 D and conditioned or distributed in substantially the same manner as described above with respect to the pressurized fluid supplied to the inlet 110 A. More particularly, the fluid supplied to the inlet 110 D will flow through the passages 114 D, the openings 112 D, the apertures 212 D, the transverse slots 232 D, the apertures 242 D, the apertures 312 D, the longitudinal slots 322 D, the sets of apertures 332 D, the longitudinal slots 342 D, the apertures 352 D, the longitudinal slots of the layer 360 corresponding to the slots 342 D, and the rows of apertures 372 D.

With reference to FIGS. 7-15, 24 and 25 , the pressurized fluid supplied to the inlet 110 E is directed to the rows of apertures 372 E and conditioned or distributed in substantially the same manner as described above with respect to the pressurized fluid supplied to the inlet 110 A. More particularly, the fluid supplied to the inlet 110 E will flow through the passages 114 E, the openings 112 E, the apertures 212 E, the transverse slots 232 E, the apertures 242 E, the apertures 312 E, the longitudinal slots 322 E, the apertures 332 E, the longitudinal slots 342 E, the sets of apertures 352 E, the longitudinal slots of the layer 360 corresponding to the slots 342 E, and the rows of apertures 372 E.

Preferably, each of the slots 322 A- 322 E (FIG. 11 ), the sets of apertures 332 A- 332 E (FIG. 12 ), the slots 342 A- 342 E (FIG. 13 ), the sets of apertures 352 A- 352 E (FIG. 14 ), and the rows of apertures 372 A- 372 E (FIG. 15) has a length of between about 20 and 23 mm.

Preferably, each of the layers 210 , 230 , 240 of the adapter 200 has substantially the same length L (FIG. 3) and width W 1 (FIG. 3 ). Preferably, the length L is greater than the width W 1 . Preferably, the length L is between about 25 and 26 mm.

Preferably, each of the layers 310 , 320 , 330 , 340 , 350 , 360 , 370 of the burner 300 (FIG. 4) has substantially the same width and length. Preferably, the length of the burner layers is substantially the same as the length L (FIG. 3) of the adapter 200 . Preferably, the width W 2 (FIG. 3) of the burner layers is between about 50 and 60 mm. Preferably, the apertures formed in the distribution layers 330 , 350 are formed therein by micromachining. Suitable devices for micromachining such apertures in the layers 330 , 350 include an Inductively Coupled Plasma Etch Machine, Model Number 601 E, available from ALCATEL.

Preferably, the manifold 100 , the adapter 200 , and the burner 300 are arranged and configured such that the back pressure present at any given one of the inlets 110 A- 110 E, 120 A- 120 E, 130 A- 130 E, 140 A- 140 E, 150 A- 150 E is no more than 25 psi when a process gas is flowed through the corresponding one of the burner modules 50 and exits through the associated apertures in the burner face layer at a flow rate of 50 slpm (standard liters per minute) of O 2 or less.

According to certain preferred embodiments of the present invention, the outer surface of the burner face layer 370 may be covered by a reflective layer. The reflective layer may be a thermally deposited oxide layer. Alternatively, the reflective layer may be a metal reflective layer, such as an evaporatively deposited gold layer.

According to further embodiments of the invention, the patterns of the apertures of the distribution layers may be modified to selectively control the distribution of flow of the burner fluids through the module 50 . For example, either or both of the distribution layers 330 , 350 of the module 50 may be replaced with modified distribution layers 330 ′ and 350 ′, respectively, as shown in FIG. 27 . Each of the sets of apertures 332 A′, 332 B′, 332 D′, 332 E′ of the distribution layers 330 ′, 350 ′ have non-uniform patterns of apertures. For example, the sets 332 B′ have apertures 334 B′ of a first size and apertures 333 B′ of a second, smaller size. Additionally, some of the sets of apertures 332 A′, 332 B′, 332 C′, 332 D′, 332 E′ have different patterns of apertures from one another.

With reference to FIG. 28, alternative distribution layers 330 ″ and 350 ″ as shown therein may be substituted for the distribution layers 330 and 350 , respectively, of the module 50 . Further alternative distribution layers which may be used in place of the distribution layers 330 , 340 are shown in FIG. 29 (distribution layers 330 ′″, 350 ′″) and FIG. 30 (distribution layers 330 ″″, 350 ″″).

The patterns of apertures provided in the distribution layer may be further selected such that one of the distribution layers has at least first and second sets of apertures of a first non-uniform pattern and a second non-uniform pattern, respectively, and another of the distribution layers has third and fourth sets of apertures of third and fourth non-uniform patterns in fluid communication with the first and second sets of apertures, respectively. For example, the distribution layer 330 may be replaced with the distribution layer 330 ′ (FIG. 27) and the distribution layer 350 may be replaced with the distribution layer 350 ″ (FIG. 28 ). In this case, each of the two non-uniformly patterned set of apertures 332 B′ fluidly communicates with a respective one of the two non-uniformly patterned sets of apertures 352 B″ of the layer 350 ″.

Moreover, as illustrated by the exemplary embodiment just described, the first and second non-uniform patterns of apertures in a common distribution layer may be different from one another, and the third and fourth non-uniform patterns in a second, common distribution layer may be different from one another. In the described embodiment, the non-uniform patterns of the sets of apertures 332 B′ differ from the non-uniform patterns of the sets of apertures 332 E′ while the non-uniform patterns of the sets of apertures 352 B″ and 352 E″ differ from the patterns of the sets of apertures 332 B″ and 332 E″, respectively. Such non-uniform patterns in the distribution layer(s) help to make the resulting burner flame emanating from the burner face more uniform across the length thereof. This results in more uniform soot generation and deposition.

The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention. Therefore, it is to be understood that the foregoing is illustrative of the present invention and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the invention.