Abstract: A compact mercury-free high intensity discharge (HID) lamp particularly suitable for automotive headlamp application has a pair of spaced and opposing electrodes sealed in a transparent enclosure defining an arc chamber. An outer transparent envelope has a first and second textured light scattering stripe on its interior surface on substantially opposite sides thereof extending continuously from one electrode to the other. The stripes widen the cross-sectional luminance distribution of the arc discharge image and make the image of the arc straighter while keeping light scattering losses at minimum so that the reduced arc peak luminance is still at the desired level. In other versions, a plurality of textured light scattering stripes of smaller widths are employed to replace a single wider light scattering stripe.

Abstract: A compact mercury-free high intensity discharge (HID) lamp particularly suitable for automotive headlamp application has a pair of spaced and opposing electrodes sealed in a transparent enclosure defining an arc chamber. An outer transparent envelope has a first and second textured light scattering stripe on its interior surface on substantially opposite sides thereof extending continuously from one electrode to the other. The stripes widen the cross-sectional luminance distribution of the arc discharge image and make the image of the arc straighter while keeping light scattering losses at minimum so that the reduced arc peak luminance is still at the desired level. In other versions, a plurality of textured light scattering stripes of smaller widths are employed to replace a single wider light scattering stripe.