Laser in daylight to photocell

For a university club project I need a laser that will noticeably affect a photocell in daylight from ~20ft. The photocell is in a small enclosure, but it still gets a fair amount of light from the surroundings. Right now I am using a very cheap 5mW (apparently) red pointer, and it is so weak that it is nearly impossible to aim at 20ft, and it does not raise the photocell output enough.

From looking around on these forums I have decided that something in the 30-50mW range would be good, and green would also be good as it would be easier to aim. Would that power level likely not damage a photocell? I would definitely need to avoid that.

The other big issue is I would like at least 30min uptime as we will be running tests for ~20 minutes at a time and it would be impossible to turn it off between each test. I looked around on laserbtb, o-like and lazerer, and quite a few did not specify operating time. It will also need to be battery powered.

Does anyone have any insight for me? We are on a fairly tight budget so the lower the cost the better (something in the $50 range would be great if possible), but I would also like something somewhat reliable. :thanks:

EDIT: Found this one that would work with a portable USB battery, but no uptime info

You said you found one, but there Is no link to see what you are talking about. I might be able to give you a link to a 532nm DPSSL that is around $50 to $60 in a lab style that outputs up to 200mW and would have a longer duty cycle than a pointer would. It would need to be powered by either a DC power source, or maybe you could use some Li-ion batteries. This would cost you a bit more, however.

Here is the link for that one: 50mW 520nm green laser module /PL-520 direct green laser diode [OL-520-50] - $59.00 : Zen Cart!, The Art of E-commerce
it was in there, but just linked under the word "this".

That would probably work okay. I could use rechargeable batteries. How big is the unit? Is it weatherproof, or at least enclosed?

This might be much better. It is a lab style fan cooled 532nm DPSSL that runs off 12 VDC. It can run for over 30 minutes at a time if you heat sink the output transistor on the driver board. I can show you how to do this. The link is: 532nm 80mW Green Laser Module TTL Modulation for Stage Light Cooling for Fan 12V | eBay and it is 80mW in power for $33.99. It is a green laser also. It will have a better beam profile than the one you are looking at.

Anyone else think digbob could use a 303?

A laser 303 is a very mass-produced chinese manufactured handheld, and is usually at least 40mW. Some can get up to ~85mW, but that's pretty rare.

532nm 5mW 303 Green Laser Pointer Lazer Pen Beam 18650 Charger Modish | eBay

I'm almost positive you could find a USA warehouse that carries them as they are insanely popular.