Method and apparatus for distributing the flux density of a light flow

An apparatus for distributing the flux density of an input light flow, said apparatus comprising:

• a plane-parallel plate made of transparent material, said plate comprising a partially reflecting optical surface at its front side facing the input light flow, and a fully reflecting optical surface at its rear side,
• wherein the partially reflecting optical surface acts upon a light flow which comprises a half of the cross-sectional area of the input light flow, and wherein an other light flow which comprises the remaining half of the cross-sectional area of the input light flow is deflected by said fully reflecting optical surface through said transparent plane-parallel plate towards said partially reflecting optical surface,
• so that by means of partial reflections of both light flows at said partially reflecting optical surface two partial flows each of which comprises a half fraction of the flux density of both light flows are coaxially superimposed in a first direction in order to form a first output light flow, and two further partial light flows each of which comprises the other half fraction of the flux density of both light flows are coaxially superimposed in a further direction in order to form a further output light flow,
• wherein the partially reflecting optical surface is selected from the group comprising polarizing and partially polarizing optical surfaces for reduction of interference effects with regard to the superimposed partial flows.