Laser beam homogenizer

摘要

A coherent laser beam having a possibly non-uniform spatial intensity distribution is transformed into an incoherent light beam having a substantially uniform spatial intensity distribution by homogenizing the laser beam with a light tunnel (a transparent light passageway having flat internally reflective side surfaces). It has been determined that when the cross-section of the tunnel is a polygon (as preferred) and the sides of the tunnel are all parallel to the axis of the tunnel (as preferred), the laser light at the exit of the light tunnel (or alternatively at any image plane with respect thereto) will have a substantially uniform intensity distribution and will be incoherent only when the aspect ratio of the tunnel (length divided by width) equals or exceeds the contangent of the input beam divergence angle theta and when Wmin=Lcoh(R+(1+R2)1/2)>2RLcoh, where Wmin is the minimum required width for the light tunnel, Lcoh is the effective coherence length of the laser light being homogenized and R is the chosen aspect ratio for the light tunnel.