A luminaire (10) comprises at least one elongate luminaire housing (16), a plurality of lens segments (22, 24, 26, 28) extending through the at least one elongate luminaire housing, the lens segments having at least one edge which is cut on an angle, wherein an adjacent edge of adjacent lens segments form supplementary angles, at least one end constraint at ends of the plurality of elongate lens segments, at least one temperature compensation unit (50) disposed between ends of the plurality of elongate lens segments.