New G7 lens for 445nm / 462nm / 520nm

The splash is not much worse, look at the lens housing, it blocks side splash by design. without glasses on at a distance it looks the same as the 3 element.

Someone asked about the G2.

These pics are both NDB7875's well focused at 14 feet.
The smaller bar is the G7 and the wider bar is the G2.

This is a test at 14 feet.




The G7 starts to burn the plywood from 14 feet in just under 2 seconds, the G2 takes 3.5 - 4 seconds to start burning focused from 14 feet.

Both lasers are NDB7875's

The splash in this clip may seem like the lasers are not at their tightest focus, but they are, the blond plywood reflects a lot around the bar and shows the artifacts.

G7's looking good, then. Might order one in the near future.

Yeah, might order one too.

Its pretty good, has a smaller dot at 14 feet and generally seems good for something to burn with but look good at the same time!

Have fun :beer:

Just remember that with 9mm size diodes in the standard 12mm housings that these focus out near the end of the threads, with 5.6mm diodes you have a couple more turns left because the emitter sits further back, but you need to use the wider 9mm size spring.

These lens's look great!:thanks:

Reminds me of the 2 element lens that was/is? sold by Olike, I liked them better than the 3 element, but they are harder to find. The difference is this new G7 looks to tighten the whole output of the diode compared to the 2 and 3 element lens clipping the edges of the diode output in addition to the extra elements doing their collimating magic.

I never could stand the G2 lens with multimode diodes, IMO the wide divergence just looks horrible, maybe OK if your into burning but when focused to infinity, ugh! I do love the G2 with 405nm diodes though.

Thanks for the review RedCowboy:thanks:

Actually the 9mm holder is too thick, it somehow affects the performance of the laser.

If you look on to sanwu's 5mm holder:


The holder is much slimmer which let the g7 lens to reveal its full potential.

I advices people to buy the lens itself and install the their own suitable holders.

Podo said:

Thanks for the review RedCowboy:thanks:

Actually the 9mm holder is too thick, it somehow affects the performance of the laser.

If you look on to sanwu's 5mm holder:

The holder is much slimmer which let the g7 lens to reveal its full potential.

I advices people to buy the lens itself and install the their own suitable holders.

Click to expand...

Can you show some more pics of that next to the 9mm holder from top and side view.
Is the width the same, is it 5mm long or wide?
Some side by side pics would help.
I do like the lens and I may well make my own holders.

I'm glad that the optics side of the hobby is getting some more attention!

I may have missed it but where can I purchase one of these lens's?
Are the thin lens holders available for sale from anyone or is it DIY? :thanks:

Chris

barthchris said:

I'm glad that the optics side of the hobby is getting some more attention!

I may have missed it but where can I purchase one of these lens's?
Are the thin lens holders available for sale from anyone or is it DIY? :thanks:

Chris

Click to expand...

Yes I have been working with wider longer focal length lens and lens pairs to greatly extend burning range without reshaping the beam.
I have started using the G7 and G2/G9 to bring the highly divergent axis in, not to a focus, just enough get the edges out of the housing threads and then focus from a wider beam to a burning point at a much longer range than any of these off the shelf lenses can.

The beam however looks like a flat funnel but it works.
I'm waiting for cylindrical pairs to reshape the beam and tame that wild axis and try to get a better solid beam, I know nothing is going to yield longer distance energy density as well as starting from an expanded diameter, but the challenge is to get a more solid beam with low divergence from affordable multimode power.

I still remember when WL first advertised the 1w arctic, it claimed 1.5 mrad and TEM00.
I was very excited, I was expecting something like a 1w blue beam comparable to a red 660nm pointer, man did they ever lie, and then I waited months and finally took a refund because they underpriced their product and couldn't deliver.
Needless to say they lost my business, I bought some of their stuff second hand but never directly.

I hope great things are to come, I would love to see some high quality high power single mode equal divergent fast slow axis diodes, but we may be focusing the hell out of super bright led's in the times ahead.

I wont give up though, even if I have to pump my own crystals, it's going t be a sight too see.
RedCowboys 75 pound laser pointer. LOL

Oh, you asked where to buy a G7?
Here:
https://sites.google.com/site/hkfew5e22/

I agree with you on the multimode laser diodes, the beam looks like a ribbon to me with the slow axis part of the beam being so thin and the fast axis so wide. I've figured out how to make beam expanders but the next progression for me is to correct the slow axis to match the same width as the fast axis so it looks more like a square instead of a ribbon.

Regarding your "75 pound pointer" project, I found this big lens for my next heavy pointer project (well, a bit too heavy to be a "pointer" or hand held unit) but it has terrible scratches on it, anyone have a good way to remove them, buff them out without destroying the curve on the lens? I've even considered taking the lens to a automobile windshield repair service and have them fill in the scratches with that resin they use. I don't need perfect, but would like to get rid of the scratches without changing the curve.



Here was my last big pointer, this one was close to 75 pounds:

^^Ugh! I hate being too new to know if you're kidding or not!

Nope, i like low divergence, thsse are legit projects.

They make a lot of lens scratch filler stuff, but I have doubts that it will work for a focusing lens.

Re grinding is the right way, but is it worth that, maybe if you could find a lens grinding service and send it off, they will have the right equipment.

I think they start coarse and work down finer and finer with the polishing compound and stick it under a rotating orbital polishing deal to get an even shape.

Your octal laser looks huge, like the size of a table, how wide is that?

Not that big, maybe 18 inches. Need to find an economy lens shop, this glass isn't high quality BK7, its cheap glass used as an old TV magnifier.

After doing further testing with a m-140 by switching back and forth between the 3 element, G7 and G2 using the same test diode with charged quality cells from a cold start it has become apparent that the G7 lets more power through.

At 14 feet with a M-140 focused onto plywood.
Time to see any burn mark appear is
3 ele------ 3.0 seconds
G7---------2.0 seconds
G2---------6.0 seconds

The G7 focuses near the end of the standard 12mm module in the 9mm long housing, but power is better, if someone with a LPM could check these I think we will see a noticeable difference.

I just ordered more G7's in the 5mm long housing, they fit the 12mm module and should have a better grip on the threads as per the design.
The lens has more threads behind it, these will probably replace all my 3 elements.

podo said express shipping is available by adding extra engrave service, 2 day shipping.

I don't know why but some of my 3 element lenses are not burning right, some 3 element lenses work well and some seem to focus but they don't burn well at all, I have checked that the lens ring is tight.
I'm going to check under the microscope, maybe the AR coating is burning off? I have noticed some dishwater big spots when focusing from raw output viewing a walls worth of light, also some 3 elements seem to focus a little further out.
I have been marking when and where I buy them, but supposedly they all come from China, they are not dirty, it's almost as if they wear out somehow, I think it may be the coating burning off, I'm trying to figure it out.

So far the best 3 elements I have bought come from Aixiz, but they do cost more, I'm trying to make sense of this, I really like the output of the G7.
G2's at 5 times the price that make a line twice as long are not the answer, I think the G7 in the 5mm housings are going to be the new standard. So far they burn better in front of every type of diode.


I have been marking what I buy when and from where and the thing that seems to happen is the 3 element will still focus but it loose burning ability, not completely, but it won't burn nearly as fast at 14 feet.
I am suspecting ar coating burn off, but I very well could be wrong.
But as this G7 is a single element and burns better I might be done with 3 elements.

I've noticed that with some of the 3 element lens's as well some are good and some suck. Checked that lens's were installed correctly and are tight. Ive also noticed the coatings are different, some have it and some dont???? When I mean no coating, I mean no coating. Im not mixing up coating for 445nm vs 635nm.

You can definitely tell that part of the diode output is being clipped with all of the 3 element though. Ive wondered how much of that clipped output is converted to heat, especially since most of the lens holders have a matt black color to them.