Patent Number: 
Section: claims

1. An elongated tubular light source envelope composed of fused quartz or fused silica comprising a pair of end sections and a central section of smaller diameter than the pair of end sections, each of the pair of end sections connected to the central section by a tapered section, each of the pair of end sections having a substantially elliptical cross-section in a plane perpendicular to a longitudinal axis and the central section having a substantially circular cross-section. 2. The light source envelope of claim 1, wherein the diameter of each tapered section decreasing from an end that mates with an end section toward an end that mates with the central section. 3. The source envelope of claim 1, wherein an aspect ratio of the elliptical cross-section of the end sections to the central section of the light source envelope is about 2:1. 4. The light source envelope of claim 1, wherein each tapered section has a cross-section that transitions from substantially elliptical at a junction with a corresponding end section to substantially circular at a junction with a corresponding end of the central section. 5. The light source envelope of claim 1, wherein a closed portion of an end section comprises an elongated stub of substantially rectangular cross-section extending therefrom to provide mechanical support. 6. The light source envelope of claim 5, wherein the stub has a substantially rectangular shape and is keyed to fit in only one orientation of a primary reflector. 7. An ultraviolet (UV) curing lamp assembly comprising:an elongated primary reflector having a substantially smooth half-elliptical cross-section and a pair of ends;a pair of end reflectors each of which is mounted to a corresponding end of the primary reflector to form a portion of a substantially half-elliptical irradiator; andan elongated tubular light source envelope composed of fused quartz or fused silica mounted to each end reflector, the elongated tubular light source envelope comprising a pair of end sections and a central section of smaller diameter than the pair of end sections, each of the pair of end sections connected to the central section by a tapered section, each of the pair of end sections having a substantially elliptical cross-section in a plane perpendicular to a longitudinal axis and the central section having a substantially circular cross-section. 8. The UV curing lamp assembly of claim 7, wherein a geometric center of the elliptical cross-section of the light source is placed at an internal focus of the half-ellipse formed by the primary reflector. 9. The UV curing lamp assembly of claim 7, wherein the diameter of each tapered section decreasing from an end that mates with an end section toward an end that mates with the central section. 10. The UV curing lamp assembly of claim 7, wherein an aspect ratio of the elliptical cross-section of the end sections of the light source envelope to the central section of the light source envelope is about 2:1. 11. The UV curing lamp assembly of claim 7, wherein a closed portion of each of the end sections of the light source envelope comprises an elongated quartz stub of substantially rectangular cross-section extending therefrom to provide mechanical support. 12. The UV curing lamp assembly of claim 7, wherein the elongated stub has a substantially rectangular shape and is keyed to fit in only one orientation of the primary reflector wherein a major axis of an ellipse of the cross-section of the light source is aligned with the major axis of the elliptical cross-section of the primary reflector. 13. The UV curing lamp assembly of claim 12, wherein each of the end reflectors comprises a spring-loaded substantially rectangular receptacle. 14. The UV curing lamp assembly of claim 7, wherein the primary reflector comprises a plurality of openings for receiving microwave radiation to excite and cool the light source. 15. The UV curing lamp assembly of claim 7, wherein each tapered section has a cross-section that transitions from substantially elliptical at a junction with a corresponding end section to substantially circular at a junction with a corresponding end of the central section.