Optical device and luminaire

An optical device comprising a plurality of lenses for projecting a plurality of parallel beams having a predetermined width towards an object area, wherein each lens comprises:

• a cavity for housing a solid state lighting element;
• a pair of opposing internally reflecting side surfaces for constraining said beam within said predetermined width;
• and
• a light exit surface delimited by said opposing side surfaces, the light exit surface comprising:
• a curved region extending from a further surface region to a stepped region, the curved region and the stepped region each extending between the opposing internally reflecting side surfaces, wherein the curved region is shaped to generate a collimated beam portion along an optical axis and the stepped region comprises a plurality of prismatic protrusions, each of said protrusions extending between said opposing internally reflecting side surfaces, and each of said protrusions comprising a prism structure that refracts light emitted from the solid state light element;
• wherein the optical axis produces a luminous distribution under an angle of 30° to 60° of said axis relative to a perpendicular to a bottom plane;
• wherein the curved region has an outer surface distal from the bottom plane, said outer surface having a maximum distance as measured along a vertical line to the bottom plane;
• and,
• wherein each location of the step region has a distance, as measured along a line vertical to the bottom plane, that is less than said maximum distance.