The output colour distributions from red, green and blue (RGB) LEDs mixed with cross linked PMMA micro particle doped PMMA mixing rods is compared to output from a plain PMMA mixing rod. Distinctive patterns with clear colour separation result with the undoped rod. These are homogenised by our mixers, resulting in white light. Light output has been photographed, measured and computer simulated at a distance of 10 cm from the output end of the rods.

We present a method for measuring the optical transfer function (OTF) of a camera lens using a tartan test pattern containing sinusoidal functions with multiple frequencies and orientations. The method is designed to optimize measurement accuracy for an adjustable set of sparse spatial frequencies and be reliable and fast in a wide range of measurement conditions. We describe the pattern design and the algorithm for estimating the OTF accurately from a captured image. Simulations show the tartan method is significantly more accurate than the International Organization for Standardization 12233 standard slanted-edge method. Experimental results from the tartan method were reproducible to 0.01 root mean square and in reasonable agreement with the slanted-edge method.

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Colour mixing of red, green and blue (RGB) LEDs is demonstrated for a 6 cm long PMMA cylindrical rod with a transparent refractive index matched micro particle (TRIMM) diffuser sheet at the output end. Ray tracing simulations have been performed, and the output light distributions, transmittances and losses modelled and compared with experiment. Photographed and modelled colour mixing results are presented for rods with and without TRIMM sheet mixers. The TRIMM particles homogenize the light output of plain PMMA rods to form white light, with negligible backscattering. A simple method for measuring the concentration of the particles in the diffuser sheet is described, and computer modeling and analysis of TRIMM particle systems is discussed.

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