this post was submitted on 14 Jul 2025
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You make them convex.
You can shape them that no matter how the light falls on it, it will align to the center. Kind of like how satellite dishes work but in reverse.
how do you do this, actually? I'm curious about the details because I just watched a video on compound parabolic reflectors, haha
a regular (ideal) convex lens with a single focal point will have the image move around as the light source moves across the sky. AFAIK satellite dishes tend to be paraboloids, which focus parallel rays onto the focal point, and if you change the angle of the light source, you'll start losing focus. Stuff like the DSN and radio telescopes absolutely do have to aim and track their targets (or are forced to follow the rotation of the earth).
satellite dishes that are aimed towards geostationary satellites don't have to move (because their targets are stationary in the sky), while stuff like starlink tracks targets with a phased array.