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Portable FAP Red

Alaskan

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E = I*R :p
 



Hemlock_Mike

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OOPS -- Maybe I'm not reading this right.

E= I X R and P = I*2 X R (that is I squared times R)

I Don't text well or EVER.

HMike
 

Sigurthr

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F**k that =P. It's V = IR, P = I2R. I reject the arbitrary assignment of E for voltage. After all, it's C = Q/V and W = 1/2 CV^2. No E's in any of those!
 

Hemlock_Mike

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Sig -- I give up. You are PC on this. The use of E for voltage as it relates to the days of "electromotive force" and there is no argument - just terms. I'll continue to eat organic food because it is carbon based.
No more technical input here. I understand - I hope....

HMike
 
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Sigurthr

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I know, hehe, I just felt like being a bit cheeky. It's just as silly as the whole "let's just reverse the direction we say current flows for no damned reason other than to confuse everyone until the end of time" (electron current vs conventional current).
 

Hemlock_Mike

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Sig -- You got it. I'll post no more technical info here because it won't relate to the smart phonys who have only thumbs. I started this here to hide the technology but -- WTH............
By the way -- The BIG solar eruptions have indeed reversed current flow but you can't see it because the meters were reversed too.......
HMike
 
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jors

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Ok, thanks!

OK - Thanks.... I have some SMA RF connectors which I might put to "good" photonic use with some mods!!!!

Jors -- Yes the module I have is marked as FAP800-40W-808 nM. Specs indicate a range of 805 to 811 nM output. Therein lies the danger. I can see 808 but it appears much dimmer than true power. When you "see" the spot hit a beam dump (charcoal briquette)
and smoke it, you know its ON........BE CAREFUL.

HMike

AND DON'T get the flu virus I got last Saturday. I'm still recovering. Lost 10 pounds in 4 days..........
 

Hemlock_Mike

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More Info on this.

I gutted an RF SMA connector to get a fitting to match the FAP module. A little machining and I have the connector, an adapter made from a brass gas fitting and a PVC sleeve which will hold the objective lens and be ADJUSTABLE!!! I will have to design the lens system yet but EDMUNDS has almost tripled the price of their glass ........ I'll look on the internet for lenses.



Chris -- Your questions relating to the TI driver may help others as I move along. This update may take time as I learn and update here. This driver may also be helpful to those powering those "fat" led modules.
The driver I'm using is a TI PTH08T250W. It is capable of 50 Amps output but rated CV -- the specs are available on the net.
I currently have my PS limited to 1.96 V max and the variable control can't exceed that. The GOOD FAP will not be connected until I'm comfortable with the device. I Plan to limit the driver to providing only 30 Amps which gives me a 25% safety margin.
- The PS has many control features including "Sense + and - ports).
Although the FAP specs recommend #8 Wire, I am running #10 because the length will be only about 6". This piece of wire at 30 Amps will make a small IR voltage between the circuit ground and the - terminal of the laser.
Here is my logic... If a higher voltage differential caused by a current increase is fed back to the Sense- input, the driver should respond by dropping the voltage applied and thereby dropping the current. I may be wrong now............
I haven't had time yet to test this out with my dummy loads but the theory works with our CC supplies.

HMike

I have ordered a -12 and a +40 mm lenses for my first expander - This should give me about 3X Mag.
 
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Hemlock_Mike

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The lenses came in today. That 7 mm lens is tiny but I think I got it mounted OK using UV cure glue. Here it is mounted on the module.



As I said, the expander uses a -12 mm input lens and a +40 mm output lens. Preliminary results at low power look promising but I only ran it just above threshold and started burning stuff at about 10".
Additional parts for the PS should be here tomorrow.
HMike
 
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Alaskan

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Great, I'd sure like to see that lens setup at some different angles and a close up of the expander lens mounting if you can post those sometime.
 

Hemlock_Mike

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Chris ---
It's almost to tiny to get a good picture.
Beam expanders are a simple telescope
and almost fall together.......
I've ordered more SMA connectors so I
can use larger lenses - I hope..
HMike

PS your phone number doesn't work -- I
just tried to call you.
 
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Alaskan

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I'd like to do something like that, but I can't because I want to use a PCX collimating lens which is several inches across to reduce the divergence further, but want the focus to be adjustable so I can focus close up to a burning point too, as I do for my NUBM44, I can focus to infinity as well as about 6 feet in away too.
 

Hemlock_Mike

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I presume you want to use the "factory" lens.
I think that was made for close focus.
What distance do you want a focus ? That fiber
clump might be a problem. I may try a GRIN lens.

HMike
 
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Alaskan

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The focal length as a burner isn't very important to me, but it would be nice to be able to focus down to a point close enough to see it burn something, a few feet away is fine, six feet would be great but my main desire is to have a low divergence output I can focus to infinity. I'm interested in what your GRIN lens can do for your project, please post when ready. I've played around with the original factory lens using a IR camera to see what it is doing, it only collimates the output of the FAP, the output isn't at a focal point at all which surprised me, I thought it would focus to a point on its output, but it doesn't.

I have replaced the factory plano-convex lens with a plano-concave lens so the output expands at a faster rate than it does straight out of the fiber ferrule. It was just easier to use the metal housing from the original collimator, taking the 12.7mm diameter PCX lens out and replacing it with a concave lens than making a new holder for the expander lens.

With the new concave lens and the beam now expanding at a faster rate, I can now use a large ~5 inch diameter plano-convex lens with a focal length of 8 inches to increase the diameter of the beam to reduce the ~18 mRad of divergence the FAP had with the original lens down to maybe 2 mRad, but I need a mechanism to move the lens back and forth a couple of inches or more to reach both infinity focus for long range spotting, as well as a close in focus to use the laser as a burner too.

I have larger diameter lenses & could possibly go up to 10 inches diameter to bring the divergence down even further to 1 mRad (so the beam only expands by 1mm per meter) but not sure the extra diameter with all its weight and extra bulk is worth it.
 
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Hemlock_Mike

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Chris --
I am working mostly on the electronics now so I have a "bed" to work with optics. That bed will allow me to adjust power to a reasonable level for testing the optics. That GRIN is really small and I'd like to avoid using it if I can get a reasonable beam.
As for burning, I almost light a charcoal briquette with no lens at 20 Amps!!!
I have more SMA connectors coming to give me more range of lens choices for expanders.
HMike

It is the lens FL + or - that determines the magnification of the expander. My current objective lens is +40 mm at
18 mm Dia.
 
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Isaac Clarke

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keep doing your sorcery on this laser Mr Magic Mike...i'm looking forward to this.... +Rep for such amazing project.
 




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