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Well good bye, It's been fun while it lasted....

Ricker

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AWESOME, what current are you driving them at?
4.5A, I don't dare go much more, though a guy wanted one at 5A and it hit I believe it was 8.6W. She liked to be a hot one though!

Edit: I'll LPM the handheld I have on sale in a couple hours, see what that's running.
 
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Alaskan

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RCB, for a beam expander, just buy a photographic condenser lens and see how much loss it has at 450 nm, even without AR coating I think building your own expander (or just use the lens as a collimator, if the FL is close to what you need) is better than buying a BE. For beam expanders, the lenses which can be used, in order of producing the best beam output are:

1. Aspheric
2. Plano Convex/PCX
3. Biconvex

I don't think I am telling you anything new with that list, but offering it up for who ever might also be looking into this. Photographic condenser lenses are not AR or anti-reflection coated (that I've found) but cheap.

Enlarger Russian condenser one lens + Diffuser diameter 71mm/2,8 inches #3
 

RedCowboy

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Searching for Photographic condenser may get me to the size double concave I want easier, I will try that search term. :beer:
 

Alaskan

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I've purchased a few condensers on ebay, usually you can find them cheap up to 6.5 inches diameter, sometimes larger. I found these too:

This lens isn't a pure PCX or quite as big as you want, but look at that AR coating. Only question I have is whether good for blue: Condenser Lens (BCX Lens) for 35mm DOF adapter | eBay - If this is a photographic lens, I can't imagine the AR would not be BB and include the blue wavelengths.

I believe this is closer to the size you want: CONDENSER LENS Assembly 3 1/2 diameter from Vtg. 2 1/4? x 2 1/4? Enlarger | eBay -

For those considering buying one of these to reduce divergence, or for long distance burning when adjusted to produce a point: You don't need a G2 or three element lens in front of it, just use it as the collimation lens and then no beam expander is needed producing a far less divergent beam without the extra loss of using three lenses, as would normally be used to expand the output from your pointer. Only concern is the depth the diode is inside the mount, if using an Aixiz diode holder does the beam expand so fast inside the tube some of it is cut-off by its diameter? If not, chuck that G2 lens and use a big PCX lens to collimate your beam instead.

More info:

If using this lens as a collimation lens so you don't need a concave or expander lens (as used in a beam expander), the only problem is what is the beam diameter through the glass at its focal length? Is it larger, or far smaller? That's the advantage of using a beam expander, it takes a given range of diameter collimated input and produces a larger diameter collimated output, you only have to be sure the input will accept the diameter of your laser beam, and that at the X factor of expansion, the output lens is big enough. Using a large lens to collimate the beam as a low loss cheap expander, you must have close to the correct focal length, or the output of the laser diode will over shoot the diameter of the lens, or be a waste of diameter, if far too small.

All of the enlarger condenser lenses I've seen so far are all PCX/plano-convex and if they have two lenses, always two PCX lenses with the curved sides face to face, the flat sides outwards.
 
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RedCowboy

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I like to protect the diode window and the G2 is very efficient so I don't mind re expanding with a double concave then focusing from a wider point further away with a much wider lens, but how to calculate the lens needed so as not to have those wings, the sanwu 3X shows it can be done, now I just want to do it bigger.

I have used a single lens to work with the diodes natural divergence from a further/wider point and zoom that down to a point, if I get wings I can keep focusing until there's a center hot spot, but the wings look like wasted energy.

For true long range I think single axis correction of the aggressive axis is the 1st order of business, then we can work with a fairly consistent beam, also when one axis diverges so much more than the other this could lead to the wings/distortions when focusing over distance problem.

If we had a perfect round beam that had a divergence that was close to the same on both axis that would be easy, I have done this with the 532nm pumped crystal pair types very well, but the beam quality is very good.

The 3 element clips some of the ends and keeps the line shorter, so a bigger 3 element setup employed further out that also has more total magnification could be used, but just a single lens working with the natural divergence is going to run into the uneven divergence problem and make wings I would think, and I have seen, but there can be a best compromise setup, I just don't know how to calculate it.

One thought was to use the 3 element and sanwu 3X back half then use a much wider lens much further out, but the line width with that setup is already longer than using the G2 ( which makes the line really long ) and a cylindrical pair to reign in the aggressive axis, that method prior to the same 3X BE makes a big difference both in near and far field point of focus dot size.

I am glad to compromise so long as I get burning results, I feel like I should build my 2 diode unit with each NUBM44 using an efficient G2 primary ( that also protects the diode window ) and a 6X cyl pair to square up the beam some, combine via PBS then re expand that beam ( double concave ) ??? and focus it down with a 1. Aspheric, 2. Plano Convex/PCX, 3. Biconvex of a much wider diameter, the distance needed will be determined by the rate of re-expansion, but it will be re-expansion of a squared up beam.

But if I can cheat and get decent burning results with a couple of wider lenses that works for me, a tight line burns too, I use a burning line of light every day in my play.

Another thought is 2 corrected beams sitting side by side will diverge where they overlap more and more with distance, that in it's self will provide 12+ watts of fun.

Thanks for the links, I will experiment with those lenses and that search term is also helpful, I owe you a rep



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Biconvex lenses (BCX) and asymmetric lenses (ABL), similar to PCX ones, have positive focal lengths combined with convex surfaces. The surfaces of BCX lenses have equal and symmetrical radius of curvature, while ABL ones have both convex surfaces but with different radius of curvature. In the latter case there is a special relationship between the two surfaces, called form factor, which identifies the best shape that an asymmetric lens can have as a function of the distances between the lens and its conjugate points.

In cases where you have equal object and image distances, i.e. when an unitary magnification is required, BCX lenses are a viable solution that can completely cancel some aberrations such as distortion, lateral chromatic aberration and coma, while ensuring low residuals of spherical aberration. These types of lenses can be used as a magnifying lenses when the object is located, from the lens, at a distance less than the focal length and observed from the opposite side. For a BCX or an ABL lens with a focal length less than 250 mm, it can be also defined as the apparent magnification the ratio Ix = 1 / (4f), where f is the focal length expressed in meters. For lenses with focal length greater than 250 mm, instead, the previously expressed formula can be expressed as Ix = [1 / (4f)] +1.


I see why we use asymmetrical lenses with multi mode beams, we still get a diverging line that grows in width to height ratio, but it compensates some for the most visible MM projection, you have seen it, where it looks like a beam inside of a beam.

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I was about to buy this and noticed the angle of the glase through the hole in the left side, it looks slanted. The rear and front shape looks good but why that slant seen through the hole?

http://i.ebayimg.com/images/g/5fsAAOSwjqVZBoLH/s-l1600.jpg
 
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I kind of lucked out with my home made beam expander, There is no noise or wings at all and most importantly no clipping, It all works well together somehow ?
 
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RedCowboy

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Hey, you have to win somewhere, you lost 2 diodes already, you deserve some good luck.
 

RedCowboy

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I wonder about these, I took apart some really nice old Japanese lenses long ago that I wish I had kept, but the ones with a wide range of adjustability could be useful if the lens coatings don't burn up.

This looks good but there could be a dozen lenses in there.

Sigma 28-105mm f2.8-4 Aspherical Zoom lens with Micro 4/3 adapter - Nice Ex++! | eBay



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I was thinking backwards, my BE's do work like telescopes.

http://www.ebay.com/itm/Fujinon-Asp...763008?hash=item2a7feb7200:g:ZM0AAOSw03lY5bN2
 
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I wonder about these, I took apart some really nice old Japanese lenses long ago that I wish I had kept, but the ones with a wide range of adjustability could be useful if the lens coatings don't burn up.

This looks good but there could be a dozen lenses in there.

Sigma 28-105mm f2.8-4 Aspherical Zoom lens with Micro 4/3 adapter - Nice Ex++! | eBay



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I was thinking backwards, my BE's do work like telescopes.

Fujinon Aspheric 16X TV Zoom Lens 9-144 mm 1.8 lens #1364 | eBay
The double convex lens i'm using in my home made BE is a bit strange because one side is more convex than the other ?


my BE's do work like telescopes
Yes so does mine......
 
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