An apparatus for focusing light in a semi-conductor inspection system, including: a first mirror arranged to reflect extreme ultra-violet (EUV) generated by a plasma source; and a second mirror arranged to focus the EUV light, reflected from the first mirror, onto a first intermediate focus plane. A homogenizing tunnel, including: a first aperture having a first shape and a first size and arranged to receive extreme ultra-violet (EUV) light; a second aperture having a second shape and a second size; and a passageway connecting the first and second apertures and arranged to homogenize the EUV light received by the first aperture. The first shape is different from the second shape or the first size is different from the second size.