I  am trying to make a homemade projector using my phone. Screen size 5.5 inches, focal length of lens is 20 cm, diameter of lens is 6 cm. The problems I am facing are:

  1. the edges are distorted;
  2. the brightness is too low.

The farther I move my phone away from the lens, the lesser the distortions​ but this also results in less light passing through the lens, so the brightness decreases.

Using stops to remove spherical aberration is an option but that will reduce the brightness of image. I want to preserve the little light that my phone can emit. How can I minimize these problems?


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