Discharge lamp having multiple intensity regions

A discharge lamp for use in tanning applications, comprising:

• an elongated vitreous tube having an outer periphery and axially opposed first and second ends which define a length for the tube therebetween, the outer periphery including at least first and second regions defined along said axial length, wherein the first region extends over a predetermined first portion of said axial length and has a helical groove path defining a series of axially spaced apart grooves and emitting radiation having an intensity greater than that emitted from the second region;
• a first electrode assembly associated with the first end of the tube;
• a second electrode assembly associated with the second end of the tube;
• and
• a coating on an interior of the vitreous tube along the entire length for emitting ultraviolet radiation when a voltage is applied across the first and second electrodes.

A method of exposing a substrate to ultraviolet radiation of varying intensity comprising the steps of:

• a) providing a substrate to be exposed;
• b) positioning a discharge lamp assembly in proximity to the substrate, the discharge lamp including:
• an elongated vitreous tube having an outer periphery and axially opposed first and second ends which define an axial length for the tube therebetween, the outer periphery including a plurality of regions defined along said axial length wherein a first region extends over a predetermined first portion of said axial length and has a helical groove path defining a series of axially spaced apart grooves formed therein;
• a first electrode assembly associated with the first end of the tube;
• a second electrode assembly associated with the second end of the tube;
• and
• a coating on an interior of the vitreous tube along the entire length for emitting ultraviolet radiation when a voltage is applied across the first and second electrodes;
• wherein the first region emits ultraviolet radiation having an intensity greater than emitted from a second region of the outer periphery;
• and
• c) exposing the substrate to the ultraviolet radiation emitted from the first and second regions of the outer periphery of the lamp.