Divergence question

What would the divergence for this diode being pushed to close to 5w be like? What would be the best lens choice for a tighter beam? If I am understanding correctly the G2 lens allows greater power but with a looser beam than the 3 element glass lens. Is his correct?
https://sites.google.com/site/dtrlpf/home/diodes/ndb7a75-3-5w-445nm-diodes
Thanks

I couldnt comment myself as i dont own a build with that diode, someone who owns one may chime in soon..........
Is that a build you have your sights set on?

I don't have one either, but from what I've seen posted around, they have worse beam specs than the "common" 445. IIRC, they are close to the horrible Oclaro 700mW 635s.

Meh it's not too bad. Does require a good bit of messing around with lenses though.

Certainly isn't anywhere as nice as a 532nm laser, compared to that, a fan on the long end of the beam. As far as mRad, what do you all think? Greater than 2.0?

yes, the divergence is terrible. better with a 3 element but still bad. one of these with a three element might even still be worse than an m140 with a g lens.

for long range, the best option for a high power 445nm may just be the osram 1.6W, I actually just asked DTR in his thread about the diode if he could do dot shots for us so we can see

I use a g lens with my NDB7A75 build, because it increases the power by nearly 1W, and I use this laser to torch ****, when **** needs torching, which really isnt that often. but the divergence is really terrible, very much like a mitsubishi 638 or an oclaro 700mW 638

while the beam is about twice as bright on the NDB7A75, when it comes to long distance you will be much better off with one of the lower powered 445nm diodes, which is why I have both. at long distane, the poor divergence will decrease the brightness of the beam anyway, another reason to go lower powered, lower divergence. It is a bright laser though, only a powerful green laser could challenge it, as far as handhelds go

you could get both lens types, but I'm telling you that even with a three element the divergence will disappoint you

this is a diode that I also think really needs a superb copper heatsink as well as a diode back half, which DTR sells. it gets hot quick. it's really a much different animal than other 445nm diodes. 1-2W is dangerous enough, and the old gen 9mm could make 3.5W sometimes, but this one can go as high as 6W, we are talking serious power that demands the highest level of respect and care. I run mine in my old copper DominatoR host, the heatsink is over a troy lb of copper, and I still stick to short duty cycles

oh and the divergence on diode lasers doesnt change with more current, the dot just gets brighter.

Is there a way to know which diodes are single mode, which are multi and which have poor divergence other than experience with them?

I cannot find high power single mode laser diode for red, green or blue, I believe they don't exist. Anything rated over about 170mw is usually multimode, if not that, a single mode being pushed hard.

I made a collection of single mode diode spec sheets here: Laser Diode DataSheets - ImageEvent

The lowest divergence multimode diode I've been able to find is the PLTB450B, the single mode version of this blue output diode is the PL450B. None of the high power laser diodes I've been able to find are near the fairly low divergence of a 532nm DPSS pumped laser, always a fair amount more divergent. Only fix for relatively high divergence multimode diode is putting a beam expander in front of their optics, but technically you could just put the collimation lens much further away from the diode than normal, with the correct focal point, and have a one lens expander that way, instead of the normal three lenses when expanding an already collimated beam. Using just a single collimation lens placed much further away from the diode would do the same thing as a two lens beam expander by producing a fatter beam and through that reduced divergence, but that kind of optical setup isn't really an expander.

I've been working with someone to build a host for me now for 520nm laser diodes which has threads built into the output end of the host for a beam expander. If I attach a 10X expander the divergence will then be reduced far below a normal 532nm laser without one.

I believe there are high power relatively low divergence single mode 405nm laser diodes, but the light from them is so faint to our eyes they aren't very spectacular, in fact, fairly dim to me at as high as one watt output, which is pushing them.

the highest power single mode diode I know of is

https://sites.google.com/site/dtrlpf/home/diodes/bdr-209-405nm-16x-diodes

the divergence of DPSS lasers can vary, the beam's properties are not derived from the pump diode, as there is a new optical cavity in the crystal. the crystal and lens determine divergence

I've got a 900mW 405nm. it's one of my favorites. best distance burner for sure. the beam may not be as bright as others, but it is very beautiful. maybe my favorite wavelength. they can do 1W, but I personally would not drive one over 600mA. plenty here do though. I've had more 405nm diodes die on me than any other wavelength, so I underdrive them even more than other wavelengths.

I told DTR he should change the lettering color on his 405nm diodes to purple, but he hasn't yet

I have never seen a 532nm laser pointer that doesn't have an expander lens in it yet, with a collimation lens in front of that of course. I didn't mean to infer their lower divergence is due to being DPSS, a lot more factors involved as ShakenAwake just mentioned, I almost touched on that too, but decided not to. Good idea to make that clear, A+. That said, I've never seen a 520nm laser host which incorporated a fixed beam expander in them yet, I would think that is a must as their divergence is crappy compared to a fairly common 1.2 mRad 532nm laser, but I've been unable to find one.

I agree, 405nm is a very beautiful color, awesome, too bad it is so faint with my S06J 12X laser diode being pushed to close to 900mw output, after collimation. One thing about 405nm, wow, it burns fast! Very effective at burning at 900mw, I believe so at half that power and lower too.

Would it be possible to get the laser energy focused to a point 1"-4" away with a G-2 or 3-element lens on the NDB7A75?

I'm thinking plugged into a wall power source pushing 5W. I'm thinking of using this to draw/etch/cut on wood/surfaces.

I believe you can with a G2 or 3 ele. (If 3 ele. will take the power), but a single mode laser diode at 405nm & 800mw might be a better choice for an extremely small focal point and thus more power density at the focal point. Anyone here use the NDB7A75 for such purpose before who can comment? I can't seem to find examples online anywhere for this diode being used that way. I bet someone is, but at max output power? Might be a lot to ask of it for that kind of duty cycle without some kind of TEC, which you might be planning already.