Collimator with improved light mixing and colour mixing properties

A collimator for a light source, the collimator comprising:

• a body,
• a cavity formed on a bottom side of the body for housing the light source, the cavity having an entrance surface arranged for receiving light generated by the light source,
• a total internal reflection, TIR, surface provided at a side surface of the body,
• an exit surface provided at a top side of the body and arranged for emission of collimated light,
• wherein the entrance surface comprises surface roughness having a roughness value,
• wherein the roughness value is expressed in an average roughness height in micrometers,
• wherein the entrance surface comprising at least a first and a second entrance surface,
• wherein the roughness value of the surface roughness of the first entrance surface is higher compared to the roughness value of the surface roughness of the second entrance surface
• characterized in that
• the surface roughness value of the surface roughness of the first entrance surface has a roughness value within a range of 1.26-4 micrometer, and the surface roughness value of the surface roughness of the second entrance surface has a roughness value within a range of 0.63-2 micrometer,
• the first entrance surface is perpendicular to an optical axis of the light source and the second entrance surface deviate from the optical axis by a draft angle of 1.5°-4°.