Beam-expander system — He-Ne laser, beam stopper, polarizer, 2 mirrors, concave lens, convex lens, screen — built using standard LEGO components. The mount system is more compact than older ones and all optical parts are on rotating stages in order to make the adjustment of the optical axis easier. This is a well-known Galileo type beam expander (4X magnification). Inset: path of the beam.
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