[{"id":22,"title":"Using a lens instead of a mirror for collimating light in display holography","sha":"a1378c7ea1ec9ff1e5848ad763570c5a","user_id":30,"state":"published","body":"When recording display holograms, the traditional method of collimating (making parallel) a diverging light beam is to use a parabolic mirror. This is a good method for the least light loss and the most perfect collimation, but the mirror needs to be an off-axis parabolic mirror, making it expensive. Otherwise an on-axis mirror can be use in an off-axis mode, if aberrations are tolerable. The longer the focal length of the mirror, the less off-axis it needs to be used and the lower the aberrations. But the longer the focal length, the more room the structure will occupy on a recording table, and the higher the risk of vibrations – the enemy of holography. So choosing the right mirror is a trade-off.\r\n\r\nAn option usually not considered is to use a collimating lens, in which case the system is on-axis and can occupy less space. It turns out that a plano-convex lens is almost the ideal shape for collimation. The compact set-up also results in a lower level of vibrations in the set-up. ","created_at":"2015-02-10T20:48:23.075Z","updated_at":"2015-03-16T12:33:22.713Z","zenodo_id":21931,"doi":"http://dx.doi.org/10.5281/zenodo.15008","subject":null,"tags":["holography","lens","collimation"],"vote_count":4,"view_count":1,"score":4.1,"deleted":false,"muted":false,"tweeted":false,"attachment_file_name":null,"attachment_content_type":null,"attachment_file_size":null,"attachment_updated_at":null}]