Using an optical fiber to guide light towards a sample plane is a highly efficient and compact solution. However, because of the angular intensity distribution of the light exiting the fiber, directly aiming the fiber at a surface would create a very non-uniform irradiance profile, which is undesired in many applications. Several optical techniques exist to homogenize the light beam, but most of them require a significant amount of space. Here, we investigate different methods to transform a Gaussian intensity profile into a round flat-top irradiance profile, while limiting the total system size to dimensions similar to the required output beam (24 mm). The intensity profile used is based on goniometric measurement, while Ansys Zemax OpticStudio is employed as raytracing software to optimize the various optical configurations. Firstly, ray-mapping techniques are used to map the input intensity to the desired output irradiance, in combination with the optimization of refractive and reflective optical elements. Secondly, solid light pipes are investigated to mix the input rays and project them onto the sample plane. Lastly, small and inexpensive hollow volume scatterers are studied to diffuse the light effectively and homogenize it. In this way, the root-mean-square irradiance (uniformity) could be reduced from 0.90 to 0.08 W/cm2, with losses less than 20%.
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