It is proposed to provide in an illumination unit (10) a light combining section (15) being adapted for receiving and combining first and second primary illumination light (L11, L12) or a derivative thereof and a light collecting, integrating and redirecting section (20) being adapted for receiving, collecting, integrating and redirecting first and second primary illumination light (L11, L12) or a derivative thereof, wherein said light combining section (15) and said light collecting, integrating and redirecting section (20) are at least partly arranged in a spatially mingled manner with respect to each other. Thereby from said first and second primary illumination light (L11, L12) collected, integrated and redirected combined primary illumination light (CL1) can be obtained and emitted as secondary illumination light (L2) having controlled spectral properties and an essentially uniformized spatial intensity distribution.