Stack exchange? On Fri, 10 May 2019, 7:00 PM RussellMc, wrote: > I wish to establish what happens to parallel light entering a parabolic > reflector from off axis angles. > The intention is to work out where the light is focused from a solar > parabolic reflector that is statically pointed as the sun moves away from > the on-axis correct-focus position. > What I wish to investigate is how effectively one or a few vacuum solar > tubes located horizontally in parallel above the dish at right angles to > the main axis will collect energy as the sun moves 'off axis'. > Such tubes will cause shadowing, but blocked light will fall on the upper > sides of the tubes. > > - I could easily do some practical experiments and observe focus spot > alterations (and will) but a numerical solution is 'a good idea'. > - I can "easily enough" sit down and work out the geometry (odds are that > it will take a few false starts to get it right but 'not too too hard') > but, > - It seems that others will have considered this before now and there may > be a ready built 'calculator' avaiable somewhere. > > Garglabet divulges many many parabola focus pages, but none seem > interested in off axis illumination of a dish designed for on axis focusi= ng. > (There are designs where the illumination axis and focus axis differ - bu= t > these too are always used with illumination along a single intended axis. > > Any leads? > > I expect that the focus spot will broaden both along the sun-track axis > and also at 90 degrees to it. Broadening along the solar path axis can be > accommodated by a thin longish collector. Broadening in focus "width" > requires additional collector tubes as it gets wider. > > > Russell > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .