7mm vs. 9mm G7 Lenses With Sanwu Pocket Lasers

Hi All:

Does anyone know performance differences between 7mm and 9mm G7 lenses with Sanwu Pocket lasers? Thanks.

-cd

I don't know specifics about these lenses, but at 9mm FL you might be cutting off part of the diode's output when focused to infinity. The greatest amount of power can be had using an aspheric glass lens with a back focus of ~2.4 mm.

paul1598419 said:

I don't know specifics about these lenses, but at 9mm FL you might be cutting off part of the diode's output when focused to infinity. The greatest amount of power can be has using an aspheric glass lens with a back focus of ~2.4 mm.

Click to expand...

Shorter FL will also result in a smaller beam diameter but a higher divergence, generally speaking.

The sanwu G7 is a single element long FL lens, it gives you 3 element performance with less power loss, but it has about an 8mm FL so it focuses out near the end of the standard 12mm copper module.

I like the short barrel G7 and 3X beam expander, although you can only catch a couple turns with the BE adaptor, the 9mm barrel G7 hangs mostly out of the standard 12mm module when focused. 9mm diodes catch about 1 turn, 5.6 diodes catch 2 turns inside the module with the 9mm barrel.

With the short 7mm barrel G7 you cant use a thumb wheel adjuster as only a couple turns of threads protrude outside the standard 12mm copper module when focused, it will grab a 3XBE adaptor and you can attach a 3XBE and do all your adjusting/focusing with the BE.

Power transmittance is roughly
3 element = 65% - 70%
G7= 85% +
G2= 95% +

But the G2 beam diverges faster, the G2 is best for close in work or pre cylindrical correction or prism pair correction.

Here's some pics


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-----EDIT-----

ATTENTION: I just read the OP asked about how these work with a Sanwu specific model laser, the sanwu lasers sometimes use a wider lens holder, the 7mm and 9mm lens barrels are M9 x 0.5 and made for the hobby markets parts/modules, your Sanwu laser may not accept these lens barrels, you may need the Sanwu specific lens holder fitted lens.

The " Pocket " may use these barrels, the " Challenger " I believe uses a M11.4 x 0.5 size lens holder if I'm not mistaken. I could be.

I got some long FL lenses several years ago. My concern with them is on highly diverging diodes some of the light is lost inside the module before reaching the lens. I have a 8 or 9 mm FL lens that performed poorly with the Mits P73 diode. Lost interest in them after that.

The orange Mits is very divergent.

The NUBM44 is also very divergent but the 7mm long G7 is wide front and back and passes more of the energy than a 3 element as is evident in it's performance, it also makes a much cleaner bar than the 3 element without the long shadow when focusing sharp/tight.

For the 44 diode I like ( Sanwu G2 )/6X cyl pair/3XBE but as an alternative G7/3XBE and a close 2nd would be 3 element/3XBE although it seems like the nubm44-47 and earlier accept the 3 element better than the later nubm44-81 which do better with the G7/3XBE. Or so it seems thus far.

Really you need a full battery of lenses AR coated for the application as each diode can work better with one than the other, I have one of those 638nm floodlight lasers and they really need corrective optics, as in G2 + Cyl pair or G2 + prism pair. The single mode ( low power ) 635/638 has decent divergence, but the 1/2 watt and 1 watt MM are floodlights.

Another factor is the 5.6mm diode vs the 9mm diode, the 9mm diode's emitter sits further forward by a rotation of threads anyway, but that's only important for the barrel depth, but I have noticed that the lens sits at the back of both the 7mm long barrel and at the back of the 9mm long barrel, but the 7mm long barrel G7 threads in further to focus....It may well be a slightly different grind, also the exit of the 7mm long barrel G7 if filled with beam where as the 9mm long barrel G7 has a smaller exit and the beam exits smaller......it seems to be a different grind as well, I like the short barrel wide open 7mm G7, it might work better with your orange diode as well.

The input sits all the way at the back of this 7mm long barrel. It should focus in even deeper for a 5.6 diode.



**This barrel is missing it's screwdriver slots that should be on the right image.


This 9mm long barrel G7 has a reduced output and longer FL, I don't see how it could be the same grind, I'm sure it's not because I screw them in about 1 turn to focus a 44 ( 2 turns to focus a 7875 ) but the 7mm long barrel G7 gets about 6 turns to focus a 44 @ 20 feet in both cases ( both get focused @ 20 feet ) and both lenses sit flush at the input, so it cant be the same grind as 1 gets 1 turn and the other gets 6.

I might have to order the G7 and see how it performs with these diodes. I know the three element lenses have a lot of loss. Always have had. Does the G7 come with different AR coatings or do you have to make due with just one?

They are 400-700 AR coated, efficiency is listed at 88%, I would be interested to see what LPM readings you get between a 3 ele and G7 (7mm) with a m-140 diode or NDG7475. I like the (7mm) G7 with the 3XBE on a NUBM44-81 build for burning at 20 feet.....what I really want is 1-2 magnitudes more power, about 250 watts sounds good in a 1/4 inch or tighter spot. :eg:

https://www.sanwulasers.org/product/lenses

Took your advice and ordered the G7 in 7 mm housing. Can't believe it takes 4 to 7 working days for them to ship it out. I guess it will be close to a month before I see it, then.

Plus the Chinese holiday, my 7475 and other diodes I won on the 22nd of Jan are still showing " Processed Through Facility SHENZHEN EMS, CHINA " of course that's only 2 weeks ago, but it feels longer.

If you use that G7 and a 3X beam expander I bet your orange diode will look much better, I put a 3X on mine and it made a big difference, went from ( tight to wide ) to ( wide to tight ) in the far field at night.

Plan on trying it out there first. Hope it works as well as you claim. I have a couple of 1+ watt 635nm lasers. Both with G2 lenses. The divergence is terrible. No, wait, I also have a 687 mW one too.

You will have a wider starting beam/ribbon that's for sure, should be more uniform.

I pretty much use a BE on everything I burn with regularly, but for pointing I like a low power green or 650nm red with good divergence so I can enjoy it without drawing attention or alarming anyone.

That 7475 I have coming wont get much use outside my back yard late night, I won't be waving it around early evening like a search light.

Anyway the line in the far field should look shorter and the starting beam wider, try and see. I liked the 7mm G7 on my nubm07.

As long as I can get a handle on the divergence without using cyl lenses, I'll be happy.

I have one of the early 180mw 638nm MM diodes in a Chinese host, o-like I think, and it has I believe a Glass 3 element for red from DTR, it made a long line or box/rectangle depending on the focus in the far field, but when I attached a 3XBE it really changed the whole ugly divergence issue, I was able to focus from wide to a point as it should be.

With a G2 it was a really long line far field to a much bigger box rectangle.

So maybe you can keep more power with the G7 and get a better divergence, but to really improve it short of shaping optics you may want to try the BE, I absolutely love the things and keep buying more, I'm looking at bigger high quality units, just hoping to see some double/triple power blue projector diodes before the green gap gets solved and greens get highly efficient.

That will be cool too, 2 PBS cubed big blues and 2 PBS cubed big greens then combined via dichroic glass, no doubt all 4 diodes will need beam shaping 1st, then once all combined into a nice big beam expander, it should be expensive....I mean fun. LOL

-----------------------edit-----------------------

I don't own a pocket series, but I think the lens screws into the head section that rotates to focus upon it's own threads with the lens captured within it, I don't think it uses the lens barrel threads for normal focusing but I could be wrong as I don't own a pocket series yet.

Performance wise the 7mm has a slightly wider beam output and seems to be a slightly shorter FL, I don't think you would notice that much of a difference with the diodes you have ordered (650nm, 520nm-150mw, 445nm-500mw) as they should be the lower divergence diodes.

But you can always order a lens and try it, I like to collect as many lenses as possible, lenses are tools and you may decide somewhere that it's just what you needed.

Podo just stated anything ordered after today won't ship until March. I ordered a G7 lens in the 7 mm housing yesterday. I'm hoping it will ship before they take off for a month.

Hi All:

Thank you all for the excellent discussion and advice. :thanks: Sanwu told me that their Pocket Series lasers are compatible with both 7mm and 9mm G7 lenses. I took RedCowboy’s advice and ordered a set of 9mm lenses. I’ll follow up, regarding any differences in performance between 7mm and 9mm G7 lenses. Thanks again and Take Care.

-cd