Cover for LED luminaires

A computer-implemented method of designing a light-transmissive cover having a defined refractive index and comprising at least one rounded corner section in between two further sections for a luminaire housing further comprising a light chamber delimited by the light-transmissive cover, the method comprising:

• receiving a defined position of a solid state light source within the light chamber;
• receiving a specification of the orientation, thickness and position of each of the further sections relative to the defined position;
• defining a first spline representing an inner surface of the rounded corner section, said first spline comprising a first inner endpoint connecting to an inner surface of the first further section of the two further sections and a second inner end point connecting to an Inner surface of the second further section of the two further sections;
• defining a second spline representing an outer surface of the rounded corner section, said second spline comprising a first outer endpoint connecting to an outer surface of the first further section and a second outer endpoint connecting to an outer surface of the second further section by calculating the position of the first inner endpoint and the second outer endpoint such that a simulated first ray of the solid state light source passing through the first inner endpoint also passes through the first outer endpoint and a simulated second ray of the solid state light source passing through the second inner endpoint also passes through the second outer endpoint;
• and
• generating an output of a design specification of the light-transmissive cover including the defined first and second splines, wall-thickness Tw, and relative positions of inner end point and proximal outer end point.