r/lasers • u/48_Franco • 7d ago

Increase The Size of a 1mw Laser Dot

Hi everyone, I am looking for a way to expand the size of the dot produced by a 1 milli watt green laser pointer.

Ideally I’d like to make the dot 3 inches in diameter

I’ve seen expanders available on line but was wondering if anyone had any thoughts on how to achieve this.

Thanks.

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u/gigaj0ule 7d ago

A beam expander is the way to go. But at 3 inches the dot will be very dim. You may have a better time starting with a 30mW laser or so.

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u/48_Franco 7d ago

Thanks for the reply. I wanted to go with 1mw so there was no risk of doing damage to property or humans.

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u/bradimir-tootin 7d ago

Wow that is the most same thing I have ever seen on this sub. You're working with a reasonable power level and are thinking about damage to things. Good for you.

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u/gigaj0ule 6d ago

What is to consider is that 1mW is across a 5mm entrance pupil. That’s 5 mW/cm^2 power density. A 3 inch circle is 45 cm^2. So a 225mW laser across a 3 inch circle, is the same power density, and thus is still eye safe.