Does anyone know of a lens that can make a laser look like a spotlight?
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Like the other comment says, this can be done with a beam-expanding telescope (which can be as simple as two lenses whose focal length ratios determine the magnification). https://www.newport.com/n/how-to-build-a-beam-expander and https://www.thorlabs.com/an-example-of-a-diy-keplerian-beam-... are a good place to start.
But it can be a bit more complicated than that , and it's often easier to use an LED.
Look up “beam expanding telescope.”
More details required.
Like the other comment says, this can be done with a beam-expanding telescope (which can be as simple as two lenses whose focal length ratios determine the magnification). https://www.newport.com/n/how-to-build-a-beam-expander and https://www.thorlabs.com/an-example-of-a-diy-keplerian-beam-... are a good place to start.
But it can be a bit more complicated than that , and it's often easier to use an LED.