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Ehgemus fan thread, post your photo's of the host he built for you.

Alaskan

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I've noticed something about a Jetlasers beam expander, you can twist the focus of one of their pointers it is attached to by a large amount and it doesn't seem to affect the infinity focus output of the beam expander much, still trying to understand why.

I've oriented a PCX lens both directions and found I like the beam output more when the round side of the lens is facing out, the flat side towards the laser. Which is your preference?
 



Minamoto Kobayashi

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Hi.
Do You mean to change the focus turning clockwise/counterclockwise the focus mechanism of the laser, so before the focus mechanism of the beam expander?
If so it is normal, it is a phisical optic limitation. I have found the same issue with my many LG modified beam expanders used after G2 or 3 elements glass lenses. I obtain the best input beam slightly defocus the input beam after the first lens.
If the input beam is convergent I obtain a short focus, if it is divergent I obain a long focus. If it is too much focused there is a chance to destroy the lens coating.
Centering procedure apart, the best way that I have found, at least in my LG expanders, to have the best GAP min/max focusing distance is this:
completely twist the LG BE lens until I reach the end of the thread (shortly before the piece from falling), then turn on the laser and look the line shape impressed in the last big lens (NOT LOOK DIRECTLY BUT FROM A SIDE!!): if the line is too short or if the line is too big and exceed the edges of the lens, so there is the need to adj the position of the G2/3 element lens (clockwise or counterclokwise).
The best position is when the output beam line almost reach the borders of the lens on the left and on the right (close to the borders without touch it).
If the line is perfectly centered in the 2 axis (fast and slow), You must obtain the best gap and the max output power available.

Your PCX lens is placed in the worse way, as shown in the photo. Are You sure that You obtain a tiny dot point? What is the shortest focus (near the aperture) that You can obtain in Your build?
 

Alaskan

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My near focus is a couple of feet away, I eill turn the lens around and see if i like it more. I didnt know the Jetlasers beam expander could be adjusted itself, i will try it out when i get back home tonight, i'm on the north coast of alaska right now.
 

Lifetime17

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Hi great build on your part being your a pilot and in Alaska smart move ingenious better to have and not need than to need and not have i always say. Kudos to you on this build.

Rich:)
 

Alaskan

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My Ehgemus hosts waiting for diodes - They are so nice I keep buying them even though I don't have diodes for them yet! I included the one on the far right which is almost finished, it has a red and green single mode in it, still needs a blue single mode diode to finish. I have several more finished and working made to order Ehgemus hosts which are not shown here.


I should have turned them to show the push buttons near the heat sink ends on most of them, oops! Most also have end cap on-off buttons.​


Harold has several hosts for sale at these two links:

http://laserpointerforums.com/f39/fs-custom-laser-hosts-new-hosts-added-today-9-2-15-a-93207.html

http://laserpointerforums.com/f39/f...ilds-new-host-added-today-2-1-15-a-94288.html

Why do I keep buying them before I have the diodes to fill them with? His work is one of a kind, unless you have a special order for something he has made in the past, he usually doesn't make the same exact host twice. If you see something you like, better get it while you can if you want it fast. Harold can usually make custom orders fast too, but I think he is getting more and more requests for custom work lately.
 
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Alaskan

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Ehgemus made another host for me. I added the chrome tube and cone with lens. Has a NDG7475T 1.4 watt output 520nm green laser diode in it. The output is an uncorrected beam, because of this the beam is a rectangle shape, but I will be adding corrective optics to it later to round out the beam more.

Why the huge lens? With a five inch lens the divergence is so low for 10 miles and greater distance this 1.4 watt output laser can theoretically produce a brighter spot than a 1000 watt 3.6 mRad divergence laser which is the typical divergence for this diode when used with a G2 lens (of course, a 6 mm G2 lens wouldn't survive that much power). At one mile distance the spot should be brighter than a 400 watt laser, at a quarter mile as bright as a 100 watt laser, at 500 feet a 20 watt laser. I'm assuming a best case with the above figures, but even if I am off by 25 percent across the board, due to its low divergence this laser will still produce an awesomely bright spot many miles away making the typical 1.2 to 1.5 mRad laser pointers more like flashlights in comparison.

Strange reality isn't it, that a laser pointer with a big lens like this which looks like a flashlight can do that. I'd like to do this same thing with a 100mw single mode laser diode, using one of those in this host would produce a much brighter spot at distance, although the beam itself less than impressive :)






Above beam shot photo taken after swapping out the 4 inch lens with a larger cone and 6 inch diameter lens. The lens is larger than the 5 inch diameter aperture, because of this it overhangs the rim. A small amount of rubber cement keeps the lens secure.

This monster takes 2 X 32650 batteries, plenty of capacity :)
 
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Alaskan

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Yea, there is plenty of room for the corrective optics, far more than needed. The cylinder lens pair I want to use to correct the beam are small with only a 12mm diameter, but adding a ledge inside to mount them to takes some extra room and then the beam needs to be expanded to match the collimation lens diameter, so all in all it is just easier to have the tube be 3 inches wide. The chrome tube which inserts into the main body of the host slides in and out to focus.

As it is now, the three inch tube is just a empty cylinder which is wide enough to allow the beam to expand to match the diameter of the lens on the end.
 
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ABarnett

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Ehgemus has made two hosts for me and I just ordered five more. It's awesome someone is making hosts of this caliber and for a good price. Its definitely adding to hobby as a whole. These hosts plus the new diodes available sucked me back into my addiction too lasers.
 

Shakenawake

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had this made recently. really pleased with how it came out, the heat sink is huge, which is good because its a hot diode. I wanted this awesome power but hated the specs. I wished I could use my PL-E pro expander on it. so I sent the adapter to him and he made a focus adapter that will accomodate the BE. I can use it on most of my lasers though the diameter is not going to match up on most. it really helps out the beam and still does nearly 6W with it on, check it out:





 
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Alaskan

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Very nice, I'm guessing you are using the NUBM44 445nm blue laser diode in it? Beam shots would be awesome if you can post them later :) I would love to have a host like that, very nicely done.

Here's a knife edge host Ehgemus made for me recently:





This was built to hold up to six knife edged diodes & corrective optics inside. The tube on the end is eight inches long and can slide forward up to 5.5 inches to allow the choice of many different focal length lenses on the output. The output holds a large 3 inch diameter PCX lens to reduce the divergence to a few tenths of an mRad. Harold has always done outstanding work, but he is getting better and better with these projects, the precision of the telescoping tube on it is which slides on the inner tube is wonderful, no slop at all.

The host was made from a Fenix TK75 flashlight body which was the best solution I could find for an easy way to get plenty of run time using this many diodes with four sets of four each series paralled 18650 batteries. The photo shows the tube using two sets of four batteries to produce 8.4 VDC at 14 amp hours of capacity. Additional battery extender tubes can be added to increase the capacity to 28 amp hours and of course, that is a ridiculous amount of capacity, even 14000 mAH is a lot.

I am not finished adding parts to make it play, but I have all of them in hand and expect to conservatively produce 5 watts of output at 520nm/green.
 
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Shakenawake

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Aye, it is that diode. I figured beam shots would be requested. I am so nervous about pointing this thing in the sky but I can say that without the expander, its a nasty g lens ribbon like the oclaro and mitsubishi 638s. with the expander, it looks like a more traditional beam. it would be even better to correct with the cylindrical pairs then use an expander but I have only the expander now. still, the difference from that alone is very appreciable. the expander adpter actually has smoother action in the threads on ehgemus's adapter than the original PL-E pro

maybe i will try some indoor shots, the divergence is so bad without the expander it's noticable after only a few yards. one problem is the heatsink is so heavy my tripod will not hold it up. shoulda had ehgemus make a heavy pommel for it too, lol.

cant wait to see what you end up with there Alaskan
 

Alaskan

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Just make sure there are no airplanes in the sky, I did it once in Afghanistan on a remote base for just a few seconds and then thought, what the hell am I doing? Showing my location!! Oops... didn't do that twice.
 




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