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Question About Corrective Optics

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Alright, since I want to lose as little power as possible in the NDG7475 I think I'm going to try out the G2/3X first and if there is too much divergence I'll try out the G7 or 3-ellement/3X. How much more power does the G7 let through btw? In a percentage.
 
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RedCowboy

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The G7 is a single element but longer focal length lens, it lets through more light than the 3 element but not as much as the G2 however the divergence is much like the 3 element because of the longer FL, around 7-8mm, near the end of the 12mm modules threads.

p.s. The lens holder on the right is defective, it's missing the thin part, the o-ring is not needed.

I don't think you're going to notice any real appreciable brightness difference between the 3 lenses, but you will notice the difference in divergence.

The G7 is noticeably wider across the glass portion than the 3 element.



 

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Hmm idk about that; I saw a video of a guy who had a NDG7475 build and there was definitely a big difference in brightness between the 3-element and the G2 lens...its a whole 400mW difference; that's a near 50% boost in power from 1W to 1.4W.

Anyway, I know the physical differences between the G7 and the other lens, but was asking how much more power does it let through than the 3-element? It must be a reasonable amount of power or else the G7 wouldn't be a popular choice...
 
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RedCowboy

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OK
A 30% increase is not the same as a 30% decrease.

For instance if you had a 100 watt laser and got a 30% increase you would have 130 watts.

But if you had a 130 watt laser and took a 30% decrease it would be 91 watts.

It generally takes double the power to visually see half again the brightness.

So a 1400mw laser would look half again as bright if it was 2800mw.

Estimates
NDG7475 @ 2.4 amps
3 element 1075mw
G7 1200mw
G2 1400mw

The perceived brightness difference is 1/7 again as bright so if 1075mw looks like a 7 then 1400mw looks like an 8

Divergence for that laser, eh
You will see that a MM beam is not round, the G2 looks good pointing at a star on 1 axis, rotate it 90 degrees and you see if fan out to a line, the 3 element trades wide for thin or thin for wide, they are both tolerable for that diode, I hold mine wide to thin. If you hold the G2 on the thin side it looks good.
The bigger diodes it really stands out as a line.
Just try it and see but always safety first.
 
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OK
A 30% increase is not the same as a 30% decrease.

For instance if you had a 100 watt laser and got a 30% increase you would have 130 watts.

But if you had a 130 watt laser and took a 30% decrease it would be 91 watts.

It generally takes double the power to visually see half again the brightness.

So a 1400mw laser would look half again as bright if it was 2800mw.

Estimates
NDG7475 @ 2.4 amps
3 element 1075mw
G7 1200mw
G2 1400mw

The perceived brightness difference is 1/7 again as bright so if 1075mw looks like a 7 then 1400mw looks like an 8

Divergence for that laser, eh
You will see that a MM beam is not round, the G2 looks good pointing at a star on 1 axis, rotate it 90 degrees and you see if fan out to a line, the 3 element trades wide for thin or thin for wide, they are both tolerable for that diode, I hold mine wide to thin. If you hold the G2 on the thin side it looks good.
The bigger diodes it really stands out as a line.
Just try it and see but always safety first.
Thanks for the explanation. I didn't quite understand the second part of your post about which way to hold the laser to make it look its best; I definitely do not want to have to worry about which way I'm holding my laser, that seems ridiculous. I'll be holding my laser so that the power button is facing up which is how I always hold the laser I have now.

Anyway, I just contacted SanWu asking if they have an adapter that would work with the PL-E Pro and they said no. Does anyone here know of an adapter that will allow me to use a SanWu 3X BE on the PL-E Pro? I looked up other 3X BE on Google and they are all like $400 plus so yeah this is an issue now.
 
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diachi

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Thanks for the explanation. I didn't quite understand the second part of your post about which way to hold the laser to make it look its best; I definitely do not want to have to worry about which way I'm holding my laser, that seems ridiculous. I'll be holding my laser so that the power button is facing up which is how I always hold the laser I have now.

Anyway, I just contacted SanWu asking if they have an adapter that would work with the PL-E Pro and they said no. Does anyone here know of an adapter that will allow me to use a SanWu 3X BE on the PL-E Pro? I looked up other 3X BE on Google and they are all like $400 plus so yeah this is an issue now.

Maybe I missed something but why not go for the JL 10x expander that's specifically intended to be used with the PL-E?

Yes - high quality optics are expensive.

Other option is to see if someone can machine you an adapter or verify independently if the Sanwu 3x is compatible with the PL-E.

Measurements for the JL expander:

 
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Theres a few reasons why I don't want the 10X BE:
1) I think there is a good chance that a 10X expanded beam will give too wide of a beam for my liking and the beam will be a alot dimmer than the laser with no BE or even with the 3X
2) I think the 10X BE looks much worse than the SW 3X in terms of how it sits on the laser, I'm not a fan of how wide it is and it makes the laser look like a flashlight/scope for a gun which I'm definitely not going for
3) I have read alot of bad things about the 10X BE about how it cuts off the beam and other things that I don't quite understand so I just wouldn't be comfortable settling with that

And yeah I can see quality optics are expensive, but I'm not looking to spend $400 or anywhere near that on a lens/BE.
I saw a 3X BE for $1,700 as well and just like the $400 one, I would be paying for something I would never need/want and that's just too expensive anyway.

I think getting a adapter machined will also be too expensive, but I'm willing to look into it since it seems to be my only option if I want the SW 3X.
I know it may sound like I'm being cheap, but I'm going to be spending $400 on a laser and 99% of people would think that's insane.
 
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diachi

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I think getting a adapter machined will also be too expensive, but I'm willing to look into it since it seems to be my only option if I want the SW 3X.
I know it may sound like I'm being cheap, but I'm going to be spending $400 on a laser and 99% of people would think that's insane.

I'm no machinist but for a one off piece like that I would imagine it'd cost you less than $50 - the materials aren't expensive for something that size, the only issue is time. Again, not a machinist, but that seems like something that could be made in less than an hour by someone experienced.

Perhaps I'm wrong.
 

DTR

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Got some questions about the losses and the better spot in the three element lenses and I figure I would just post it.

There are a few reasons for the losses in the three element lens. There are three elements in there and say each has 3-5% loss each and that is successive loss. Then there is the biggest loss in the three element lens(also the reason there is a perception of a reduction of spot size which not so much a reduction in divergence but beam clipping) is that is a long focal length and it actually does not collect all the light. The outermost edges of the beam is clipped by the aperture of the lens and not passed.

These are numbers I am just going to throw out there and they may be a little off but this would be a good example of what happens. Say there is a initial loss of 15% from clipping. So if you start with 15% loss that is 85% then say 5% in the first lens element leaving 81%. Then 5% through the next 72% and then the last lens 5% leaving 69%. Those are estimates but that is approximately how it works. It is different with different diodes as well depending on the output profile at that first stage of loss. Enlarging the aperture more might be a first thought but then the spot size would increase again which is one of the main advantages.
 
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RedCowboy

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The 3 element will clip the ends of the diodes bar shaped output as illustrated in this raw output pic, however the ends are not the most energetic part of the diodes emission, you can see when burning on a block of wood with either lens that the center of your spot burns first. ( WITH OUR LASER SAFETY GLASSES ON OF COURSE )

The G2 is a fine lens and has many uses, up close material cutting is a strong point for the G2.

It's not life or death, it's a hobby, everyone should have both lenses and experiment, see what works best for your application. They both have strong points.

You will get a lower power meter reading with a 3 element than a G2'

Here's a couple of videos that compare that difference.

At 4 amps the 44 diode puts out 5 watts and 6.35 watts, that's a 26% increase with the G2. I am not trying to argue any points, just share comparative info. These are DTR's videos and pic that I linked to.

Here's a NUBM44 with a 3 element.

Here's a NUBM44 with a G2, NOTE the meter tops out at 6.8W
 
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GSS

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RCB, DTR, this is it. No possible better way to explain it:beer::beer:
If someone is willing to pay for a good laser then all sense go's to getting a few different lenses to play with and come to your own conclusion. Its simple for the most part and fun:)
 
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Thanks for the posts guys, I think I have a pretty good understanding of the different lenses now and I will experiment and decide which lens to get on my own.
 




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