Hello - nice to be here - from Wales

I know naff all about lasers which is why I've joined this forum, hopefully to learn a little before I blind myself or someone else.

I recently bought some lasers from China to point out the stars and impress my GF - all were under US $10.00.

First was a green laser from FastTech branded 'DX dealextreme' !! - it states it is <5mW. The beam is not visible in daylight but it will cast a small but visible spot onto a bell tower 275m away at night. The beam is quite thin but ok as long as there's not too much ambient light.
When I first got it I thought it wasn't working as it was very dim but what I have worked out is the laser head needs to be warmed up before it will get bright - sticking it under my arm pit for 5 minutes does the trick --- is this normal?

Hoping for a better beam I got a purple laser from ebay branded 'VL Laser 303' - it states it is <100mW. I was very disappointed with this laser which had a very thin faint beam at night and was useless for pointing out stars.
It seems to have died as it will now only produce a very, very dim spot on an object 6 inches away --- is there anything I can do to try and fix this?

I've just received the last green laser I ordered - from a dealer on Ali Express - this one is branded 'Laser 301' - it states it is < 10000mW !!!!
The beam is visible in daylight and very strong at night - it will project a bright spot (i estimate about a 1 feet in diameter) onto the side of a 29 story building 1.4Km distant
I'm sure it can't be 10 watts but would like to know what it's pumping out --- could someone point me in the direction of a very cheap meter and a decent pair of safety glasses?

Actually this last laser has scared me a little and is what has prompted me to join this forum :beer:

Steve.

Welcome to LPF!

-Alex

Welcome to the forum!
Sounds like you have been having some fun with ebay pens. Those Violet 405nm lasers aren't good for star gazing because it is just above what the human eye can perceive on the visible light spectrum. That green will work! But you're right it's not doing 10W and be careful, they don't always have ir filters!
Have fun be safe!

Glasses can be found here. http://www.survivallaser.com

Hi Steve and welcome to the forums.

A lot of the cheap ebay pens are really hit and miss when it comes to spec and quality. I once owned a low-powered 'leadlight' green dpss laser that didn't lase below ~15C ambient. The armpit trick will help to warm the module .

Not sure on the output of your 301 but from what I've read it could be between 60-80mw. Correct no way it's doing 10W, that would set you back £thousands

Welcome! :yh:

I'm sure it can't be 10 watts but would like to know what it's pumping out --- could someone point me in the direction of a very cheap meter and a decent pair of safety glasses?

Click to expand...

Those "Laser 301 / 303" are good for star pointing and for beginners, usually, it produces 50mW ~ 100mW, a good part of it is IR from the DPSS module, since those are chinese and the control quality are bad, there's no way to know the true power unless you LPM it, the most cheap LPM I could find is the Radiant X4.

If you're lucky to get a powerful one, then you should be able to fire a black match or cut electrical tape with it.

About the goggles, I got this one.

When I first got it I thought it wasn't working as it was very dim but what I have worked out is the laser head needs to be warmed up before it will get bright - sticking it under my arm pit for 5 minutes does the trick --- is this normal?

Click to expand...

This is normal with those cheap DPSS lasers, it produces light using a couple of delicate crystals, every °C will make it expand or contract, changing it characteristics, after a warm up time, it should get stable.

alessnilsen said:

Those "Laser 301 / 303" are good for star pointing and for beginners, usually, it produces 50mW ~ 100mW, a good part of it is IR from the DPSS module, since those are chinese and the control quality are bad, there's no way to know the true power unless you LPM it, the most cheap LPM I could find is the Radiant X4.

Click to expand...

Ahh! - $100 for a relatively inexpensive LPM - the mW my 301 pumps out will have to remain unknown

alessnilsen said:

If you're lucky to get a powerful one, then you should be able to fire a black match or cut electrical tape with it.

Click to expand...

I just tried firing a match with the 301 and it does it in just over a second from about 2 inches - would this be totally due to the energy in the 530nm light or does IR play a part?

alessnilsen said:

About the goggles, I got this one.

Click to expand...

Thanks - nice and cheap as well

alessnilsen said:

This is normal with those cheap DPSS lasers, it produces light using a couple of delicate crystals, every °C will make it expand or contract, changing it characteristics, after a warm up time, it should get stable.

Click to expand...

Yeh, the DX likes to be cuddled before it wakes up but the 301 doesn't seem to care what the temp is.

I just tried firing a match with the 301 and it does it in just over a second from about 2 inches - would this be totally due to the energy in the 530nm light or does IR play a part?

Click to expand...

Hard to say, the best method will be putting a IR filter at the output and try to fire a match again.

Yeh, the DX likes to be cuddled before it wakes up but the 301 doesn't seem to care what the temp is.

Click to expand...

Those 301/303 are more stable than the pen lasers, I got one a time ago that had the "mode hopping" effect, if you're curious, here is a good topic about it!