What Divergence should someone expect to see from a $15 Green Laser 532nm 80mW DPSS ?

Is 0.625 Divergence and a nice round dot at 80m better than should be expected from a $15 Green Laser 532nm 80mW DPSS ?

It's been 1 hour and no posted has posted in any other thread or written a new thread, I need to get this moving! :yh: op:

I've heared talks of anything <1mRad being very good. 0.6mRad would be astonishingly good. Member Merpie101 got my 635 laser I sent to him and he recorded a similar divergence, which is pretty amazing considering it's 635, and only cost me $8, and it's a diode, not DPSS!

-Alex

0.6mrad is crazy ive never had a green with that kind of divergence. id say you got really good divergence on that. speaking of 0.6mrad i was going to try to do a test to see if i can get a spot size from a half mile away and see how big it is there, but thats for another post

Thanks Hap, My dot was 52mm at 105 paces BUT i've been messing around with some lenses i have and i started by removing all the plastic lenses after the crystal and now i'm only using one concave lens and one convex lens set about 80mm away from the concave lens, the beam is very round and tight now !

For a while they were setting the inexpensive green pointers up for lighting a match as that's what the buyers were wanting, but the far field spot suffered, then the ready made 15 dollar range lasers went user focusable, now the fixed focus units seem to have returned to the best possible infinity focus, that includes the 15 dollar advertised 80 mw modules for what I have seen.

They employ a little acrylic bi-concave/bi-convex BE in the output end of those 80mw modules because the beam straight out of the crystal is really thin but diverges pretty rapidly.

So if they are tuned for match lighting then no matter how much you adjust the focus it just wont make a good tight far field dot, but if you get one designed for the best possible divergence then they look pretty good, I don't have a numeric value but they do make a nice tight looking dot in the distance.

I should also mention that the 520nm direct 50-100mw diodes can be focused to a satisfying tight spot far field. Again I don't have a divergence number, " pretty good " is my answer for what it's worth.

This laser is a bit unconventional looking but the beam is great !

Yea, I've done that too with 532's by replacing the output lens with a wider longer FL lens to get a much tighter dot, and you can zoom focus them, I like the quick zoom on the 532's.





The wet grass makes the spot look big but it can focus very tight in the far field.

Yes, without my laser safety glasses on the dot looks larger then it really is....

What's the output power on your slide focuser ?

It was advertised as a 200mw 532nm from laserlands when I bought it probably 2 years ago for 65.00, but next to this 50mw 520nm PL520 I got from DTR it looks pretty close as for brightness.

It took me a while to warm up to the 520's but these PL520's are really good, they do have a beam that's rectangle shaped at the aperture although it's not anything that really stand out unless you look at it closely, but in the far field it's every bit as tight as a 532nm looks, it's running a green AR coated 3 element lens.

If you don't have a PL520 let me tell you, you do want one, you can see it's more green with your eye although my cheap camera doesn't capture the color shift, it's less yellow and that's pretty cool right there, but they also focus tight, I was surprised.

532 left, 520 right

https://sites.google.com/site/dtrlpf/home/diodes/pl520-520nm-laser-diode

The next diode i'd like to get is the NDG7475 1W 520nm

1w 520nm NDG7475 will have a beam divergence like the NDB7875, it's not bad but I would love to see even a half watt of single mode 515nm.

RedCowboy said:

1w 520nm NDG7475 will have a beam divergence like the NDB7875, it's not bad but I would love to see even a half watt of single mode 515nm.

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Are there any Singlemode Laser diodes over 1 watt of 515nm/520nm/532nm ?

I've seen some very expensive prototype diodes somewhere, but I can't think of any off the top of my head.

I really like great beam specs but if i'm being honest part of the appeal for me how dangerous a given beam is as well as it's visibility.....

I just did a much more accurate test of the mRad at a much farther distance and the first calculation of 0.625 Divergence is off.

These measurements were taken much more carefully and over a much larger distance, The 2mm beam is 138mm at 160 paces or 122 meters or 405 feet which gives a true mRad of 1.11 but the dot at that distance is still very round and bright, I don't think a very round and bright 1.11 mRad beam for $15 is all that bad is it ?

Accutronitis said:

I just did a much more accurate test of the mRad at a much farther distance and the first calculation of 0.625 Divergence is off.

These measurements were taken much more carefully and over a much larger distance, The 2mm beam is 138mm at 160 paces or 122 meters or 405 feet which gives a true mRad of 1.11 but the dot at that distance is still very round and bright, I don't think a very round and bright 1.11 mRad beam for $15 is all that bad is it ?

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That beam doesn't get any less round as it travels... at least not over that distance. It's as round as it was when it left the OC.

But yeah, that's pretty decent. Advantages of DPSS! :beer: Even the cheapo pointers have good beam specs these days, I don't see as much mode hopping as I used to years back.