regions on the substrate 24 which receive the greatest amount of radiation is changed by adjusting the position of the side elements the reflective surface provided by the elements 4 6 has a generally rectangular cross section in comparison with known lamp assemblies having parabolic or elliptical reflective surfaces the overall dimensions of the assembly are reduced so achieving the industry desideratum of small assembly size the horizontal distance between the ends of the reflective surface i e the distance between the lower ends of the side elements 6 is also reduced this has the benefit of reducing the ir output for the reasons discussed above it has been found possible to arrange the elements 4 6 such that there is no internal reflection and therefore light from the lamp 18 is used more efficiently it was unexpected that the efficiency could be so great while still allowing for an overall reduction in the size of the lamp assembly 2 tests have shown that in comparison to a known shuttered unfiltered lamp the lamp power required for a given uv output intensity is reduced thus the lamp assembly 2 enables cost savings in terms of reduced power requirement with the same output intensity alternatively for a given power level the intensity and therefore the speed of curing is increased and this allows substrates to be moved past the lamp at a greater rate the.