mounting bracket fig2 shows interconnection of fresnel lenses in a luminaire fig2 is a perspective view showing how a series of circuit boards are interconnected to form a full luminaire circuit fig2 is a cross sectional view showing an luminaire connected to the end of a shelf and having a thermally insulating safety strip and fig2 is a diagrammatic representation of an end cap arrangement for electrical connection the invention provides a luminaire having a lens with optical characteristics to redirect and refocus light from its source so as to maintain a substantially uniform illuminance across a target plane so that the area illuminated by the same quantity of flux from the source remains constant the invention also provides display cabinets incorporating such luminaries referring to fig6 a luminaire 1 having a linear series of led sources 2 and a linear lens 3 is shown diagrammatically in cross section the lens 3 is moulded so that its optical characteristics and most importantly focal length vary continuously across the cross section this variation compensates for the fact that the luminaire is mounted at an acute angle to a target plane 4 as indicated by the lines indicating equal illumination intensity along the lengths u201c a u201d there may be a product shelf of a cabinet in the plane 4 for example alternatively the target plane may be a vertical plane through the front edges of a series of shelves one above the other referring to fig7 a luminaire 10 has a lens 12 with two halves 13 and 14 each half designed to produce a different refraction in the light emitted from a source 11 in.