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ArcticMyst Security by Avery

WTB: Q Switch for ND YAG & Aspheric Lens 4/λ, 50mm or larger dia.

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WTB opto mechanical Q switch for ND YAG

And......

Anyone have a large diameter aspheric lens suitable for laser beam collimation sitting around you want to sell, or know where I can find one? Looking for a 2 inch diameter or larger laser quality 4 lambda or higher accuracy aspheric lens, the larger the better.

I can find under one inch easy enough, one to two inches harder, three inches or more not. Even when looking on Edmund Optics web site I cannot find 3 inch or larger, not that I would pay their price, the prices are high enough for their 1 inch diameter aspherics.

Why Aspheric? Aspheric lenses are not uncommon for our laser pointers, true G2 lenses are aspheric, but in my opinion their drawback is their small 6mm diameter, but for projectors which use small galvo controlled mirrors, the beam diameter needs to be small, divergence taking a back seat. Since I'm not a projector hobbyist (yet) low divergence is more important.

Here's a cut and paste from Edmund Optics regarding this type of lens:

Aspheric Lenses are used to eliminate spherical aberration in a range of applications, including bar code scanners, laser diode collimation, or OEM or R&D integration. Aspheric lenses utilize a single element design which helps minimize the number of lenses found in multi-lens optical assemblies. Said another way, unlike conventional lenses with a spherical front surface, aspheric lenses have a more complex front surface that gradually changes in curvature from the center of the lens out of the edge of the lens. This reduction in total element count not only helps decrease system size or weight, but also simplifies the assembly process. Integrating aspheres into an application such as focusing the output of a laser diode may not only decrease total cost, but may also outperform assemblies designed with traditional spherical optical lenses.

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EDIT July 22nd 2016:

There is another optical item I am in search of, a small ~1/2 inch diameter IR PBS polarized beam splitter cube. I need one with AR coating for about 800nm, I can find them on Aliexpress for 50 dollars, plus another 40+ dollars shipping, or another one on ebay for close to 140 dollars but I don't want to pay that much. Here's the bay listing to give an idea of the specs I'm looking for:

Link: 1pcs 10mm Polarization Beam Splitter Cube PBS 600 1100nm A329 LW | eBay

Polarization beam splitter cube

Size: 10*10*10MM

Dimension tolerance: +/-0.1MM

Finish: 40-20

Type: Lambda/4

Wavelength: 600-1100NM (I need ~800nm)

Also, I still have not found a 3 inch diameter high quality 4/Lambda or better 3 inch aspheric lens, I am now looking for a 2 inch diameter but still need the high accuracy surface specs.
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

Thank you, I just tried looking through their stock but not one aspheric lens listed in their inventory between 1mm and 300mm diameter. Their search engine lists them, but none can be found in stock.

Warning Pet Peeve Banter:.... I moved this to the bottom of the post, it's not happy news about the Surplus Shed....

Edit: I found this nice 1+ inch lens on ebay (photo below), might be a good one for the NUBM44, but the price he put it up at is astronomical, not that the new price for this same thing wouldn't be that high if it is a precision ground lens and not a molded aspheric, but as NOS or new old stock, too high. Although they did accept an offer of 25 dollars for one which is very reasonable if this lens is a high quality high accuracy ground lens. Looking at the main photo I wonder if the colors I see are a hint of AR coating? If so, wow. I remember seeing this same listing at the same price two or three years ago, obviously not moving very fast, or they have a boat load of them:

http://www.ebay.com/itm/The-Bendix-Corp-Military-Grade-Aspheric-lens-31mm-DIA-/222156270288

aspheric.jpg


Cheap molded aspheric lenses which look much like this one can be found on ebay for a couple of bucks each, but they are made with cheap glass for LED arrays. Although the refractive inconsistencies cannot be seen inside the glass with the eye, shoot the light from a laser diode through them and they sure show up. I bought a 2 inch diameter NOS Edmund Optics aspheric lens from another seller on ebay some time ago, it too was molded and made from cheap glass, had a swirl pattern the cheap Chinese LED aspherics have show up when shooting the light from a 1 watt 520nm laser diode through it. EO makes low end lenses too, I found.

So far, all of the inexpensive aspherics I find on ebay are just that, cheap.... I'm hoping this one will be different. If I can't find 2 inches, or 3 inches diameter precision aspheric lenses, I will have to settle for this one, if that is what it is. Why aspheric? Less spherical aberration, PCX lenses are fine for beam expanders, but aspherics the best for that or collimation, unless going to a mirrored reflector made for telescopes which will probably be my next project, although not as mount friendly as refractive lenses, if you want a large aperture for lower divergence with less distortion, that seems to be the way to go..

Warning Pet Peeve Banter: They have some deals from time to time, but I stopped buying from them because even though stock was shown on their web site, too many times I would pay the full amount for multiples of one item and then a week later, only after receiving my package, did I learn they didn't really have the amount I ordered in stock. Although they would refund the difference, I can't use half of the parts to finish a project, I need all of them and since much of their surplus stuff is unique, I'm screwed, left holding the bag with parts I can't use. Although I might consider ordering one item at a time from them, hard to mess that up.
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

Thank you BB, those prices are good but they state they are for High-Efficiency Illumination Applications. I wonder how well they will perform as either a beam expander or collimator for VIS lasers? I found a 3 inch diameter one listed on that page with AR coating for 64 dollars, cheap if it will work well to collimate the output of a NUBM44 450nm laser diode..

I already ordered one of those you found on ebay too, already shipped and on the way, I just don't know if it will have those swirls from using cheap glass or not yet, but I paid 20 dollars for it. It is made for illumination too, so might not have as accurate a curve as I might want for use to collimate a laser diode, but if the glass has a consistent refractive index throughout the lens, that's better than I've found so far.

order.jpg
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

Well, from the description the molded ones are good, or at least sufficient, for collimating light from fibers or fiber optics. They're not those precise CNC-polished types, but you'd be paying $800 or something for one of those in the diameter you're looking at. The condenser lenses seem to be the only ones that come in that size for the molded types.

Have you also looked at using camera lenses?
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

BB, the reason I am looking for precision aspheric lenses is because I don't know enough, I don't know the accuracy needed to use one of these lenses as a collimator when 1 to 3 inches diameter or more. I've been researching the lambda needed for PCX lenses and have come to believe 4 Lambda is good enough for a bottom end, but that 8 lambda or higher is preferred, all the way up to 20 Lambda or 5% wavelength accuracy which I can't afford. I've been looking at photographic aspheric lenses, but the specs don't tell me enough to make a partially educated guess to know how suitable they might be for lasers. Perhaps they are high precision lenses with 10 to 20 Lambda surface accuracies for all I know, do you know?

Maybe I am assuming I need a precision lens to produce a nice beam when a cheap lens with only 2 lamba surface accuracy will work just fine? I don't know what the common surface accuracies are for aspheric lenses made for lighting purposes compared to aspheric lenses made for lasers. These questions are just now coming to mind as I write this, so I have more research ahead of me, can you give any guidance on these questions? My desire is to produce a low divergence beam with low spherical lens aberrations, but I don't have a need for it, just want to build a laser pointer with as low a divergence as I can with as perfect a beam as I can reasonably afford for a hobby laser. Can I justify the expense? Nope, just want it. I am also hoping a large aspherical lens might help reduce the astigmatism problem I get using a NUBM44 laser diode which causes a large amount wing splash. Maybe an aspherical won't help in that regard, but I'm curious to see.
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

BB, the reason I am looking for precision aspheric lenses is because I don't know enough, I don't know the accuracy needed to use one of these lenses as a collimator when 1 to 3 inches diameter or more. I've been researching the lambda needed for PCX lenses and have come to believe 4 Lambda is good enough for a bottom end, but that 8 lambda or higher is preferred, all the way up to 20 Lambda or 5% wavelength accuracy which I can't afford. I've been looking at photographic aspheric lenses, but the specs don't tell me enough to make a partially educated guess to know how suitable they might be for lasers. Perhaps they are high precision lenses with 10 to 20 Lambda surface accuracies for all I know, do you know?

Maybe I am assuming I need a precision lens to produce a nice beam when a cheap lens with only 2 lamba surface accuracy will work just fine? I don't know what the common surface accuracies are for aspheric lenses made for lighting purposes compared to aspheric lenses made for lasers. These questions are just now coming to mind as I write this, so I have more research ahead of me, can you give any guidance on these questions? My desire is to produce a low divergence beam with low spherical lens aberrations, but I don't have a need for it, just want to build a laser pointer with as low a divergence as I can with as perfect a beam as I can reasonably afford for a hobby laser. Can I justify the expense? Nope, just want it. I am also hoping a large aspherical lens might help reduce the astigmatism problem I get using a NUBM44 laser diode which causes a large amount wing splash. Maybe an aspherical won't help in that regard, but I'm curious to see.
Just by looking at them you know aspherics have short focal lengths. Now such a short focal length is needed for constructing a Keplarian beam expander, but you still need a longer focal length lens to collimate which isn't likely to be aspheric. An aspheric may be useful as the first lens in such a system, but it's not the lens I would choose except for experimentation. I've not seen any line drawings or descriptions of that type of expander using an aspheric lens. Go satisfy your curiosity though. Personally, I would build a Galilean beam expander afterwards.
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

I've been playing with a NUBM44 laser pointer and found I can reduce the wings, well, eliminate the wing splash if I use a PCX lens with a relatively long focal length, compared to our pointers. 18 inches of FL and only using 25-50 percent of the lens aperture allows me to focus the beam to a fine spot 20 feet away without wing artifacts. My primary interest in the aspherical lens is not for this, but to simply make a one lens collimator which has low spherical aberrations. Why? Just because I'm learning and want to see the difference, maybe this is something which requires lab gear and I won't see much difference, I don't know.

Rearding surface accuracies, I just found this paper on EO for three different grades of aspheric lenses: http://r.search.yahoo.com/_ylt=AwrB...load/182/RK=0/RS=9IFcJMOyKbvpreUOPo6nZQ8jZGQ-

I'm still searching to know how accurate photographic aspheric lenses are compared to aspheric lenses made for illumination or for lasers. Looking at the above paper I linked to, even 1/2 lambda might be enough accuracy for my puposes, but I'm guessing, I don't know how much that would affect the beam when using a lens like that to collimate a beam with.

I like beam expanders, but to lower the divergence I prefer letting the beam expand by simply using a longer FL lens with a wider diameter lens instead, that way I don't have the loss of two additional lenses in front of my laser diode I would get when using a conventional beam expander. I have a large 160X 150mm aperture beam expander at home to play with, plus several others made by reputable laser BE manufacturers, so beam expanders have become a hobby.

Looking at the EO paper on aspherics I linked to above, it appears illuminator aspheric lenses have irregularities of 1/2 lambda, aspherics for less than high precision laser use 1/4 lambda, high precision laser use 1/20 lambda, lambda of course meaning wavelength. From this I am hoping to find regular photographic aspheric lenses have at least 1/4 lambda accuracy.
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

I ran across their web site a couple of years ago and again recently, I'd love to have one of those but when I checked in prices, ouch.

Edit: Looking at the EO document on aspherical lenses, I am finding there is another accuracy measurement I need to be concerned with:

Power (Spherical) 2λ, 1/2λ, 1/10λ

2λ for "commercial" which I interpret as illuminators, 1/2λ for laser use and 1/10λ for precision laser use. The use of the word power is somewhat confusing to me, but I guess that means curvature accuracy.

800.jpg
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

Wow, look at this bad baby, close to 5.25 inches diameter. Only thing is, the glass might have inconsistencies in it like the smaller Chinese aspheric lenses I've tried, when shooting a laser light through it making a pattern of the swirls of glass inside you can't see otherwise.

Diameter 134mm optical glass aspheric lens,plano convex lens for car lamp,motorcycle led lighting,flashlight-in Lenses from Industry & Business on Aliexpress.com | Alibaba Group
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

I'd probably just experiment with the inexpensive stuff to see if it's even feasible to get a good quality beam using such a lens arrangement. The precision lenses will only make it a better spot/beam, but you should be able to tell whether you're achieving the results you're looking for with the less precise variants.

Like Steve001 mentioned, a classic Galilean beam expander is probably the way to go. You'll need that level of control since your laser diode is diverging at one angle, while your lens will have a separate angle as dictated by its focal length. They may not be compatible in order to have the entire diode's output filling the disk at the back of your lens. Chopping off wings, for example, means that you're truncating the beam, losing output power.

Try this out before you lay down some money:

Do an ABCD optics matrix calculation (remember that angles are measured in radians) with your intended diode and lens. Determine whether you can even collimate your beam given the lens focal length and diameter, and your laser's divergence.

You might also "practice" with an optical breadboard, some adjustable mounts, etc. just to see if you can get a good quality collimated beam with cheaper optics. I find it difficult to get good beams without precise control, and I wouldn't even begin buying precision optics until you have the mechanical part down.
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

Ohh in 2007 i purchase HID lights and used it on the car then i converted back to original i still have the HID lenses and bulbs, its it safe to use the lenses form the HID Bulbs on the lasers its glass !
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

BB, I used a Mace of Doom laser pointer with a 70mm diameter 500mm FL telescopic camera lens setup and when pointing into the night sky, the beam looked good, except for some astigmatism wings being produced by the lens with a 6+ watt NUBM44 diode. I was able to completely get rid of the wings by using the variable iris inside the camera lens assembly as a spacial filter, truncating the beam with about 10% loss of power. Here is how I set this pointer up to work with the telephoto lens:

Using a MrCrouse Mace of Doom pointer, I de-focused the G2 lens to the point the beam spot diameter it produced on the telephoto output lens was about 80 percent its aperture, then I would adjust the zoom focus control on the telephoto tube to fully collimate the beam the rest of the way to infinity focus, this worked great. However, the spacial filter was costing me 10% of my power output. Good news though, when trying to solve a focus issue caused by the position of the telescopic lens on my pointer, I found the wing artifact problem was eliminated by simply reducing the spot size on the output lens by half, only filling 50% of the PCX collimation lens diameter. While this got rid of the wings there was a price, I lost nearly half of the beam expansion I could have had otherwise and with that, the divergence about twice as high, although with 1.25 inch of expansion, acceptable..

Here is a link to a thread I posted about using a telephoto lens as a beam expander: http://laserpointerforums.com/f49/m...photo-lens-converted-beam-expander-95082.html

db8e0fdd-0fe7-4160-887d-73ea041bf3df.jpg


I've also used a large 4 inch diameter photographic condenser PCX lens alone, letting what I will call the raw output of a NDB7475T green 1W 520nm laser diode expand for a length of about 4 inches before hitting the PCX lens, this expanded the beam without the extra lenses used in a Galilean beam expander, and from what I can tell by eye, the beam looks fine. Whether the beam has problems at the far end , I can't see.

Thank you for the link to the optics matrix calculation, I haven't worn my math cap for so long I got a head ache for a moment looking at it, I haven't worked with a formula like that for 30 years. Although not really that complex, it has just been a long time.

I already have a few verrrry cheap aspherics to experiment with, but I found some 25mm diameter 60-40 surface quality .75um RMS surface accuracy aspheric lenses on ebay last night for 20 bucks each, full price is $225 dollars each from Edmund Optics, so I bought a couple to experiment with. While these 25mm diameter lenses will be big enough for use as part of a beam expander when using single mode diodes which already have a relatively low divergence, they are too small for what I want to use with multimode diodes.

http://www.ebay.com/itm/181096889449 -

http://www.edmundoptics.com/optics/optical-lenses/aspheric-lenses/precision-aspheric-lenses/47730 Seller accepted my offer of $20 each.

Alien, I don't know why those glass plates wouldn't take the power of one of our laser pointers, as long as it is clean. Why do you want to use the plate?

I would still like to find some quality 3 inch diameter or larger aspheric lenses, but I don't think I could afford the quality of the 25mm/1 inch lenses, they would have to be 2 Lambda for my wallet, but if that works, I'm good.
 
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Re: WANT TO BUY: Surplus Priced Large Aspheric Lens (3 inches diameter or larger)....

I don't think there's really any other solution than that truncation and perhaps correction afterwards for the new beamsize + divergence at the aperture.

As for the ABCD matrices, you don't have to do them by hand. You can just program them into something like Octave (or Matlab if you own it) and just chain together the matrices that represent the different optical component interfaces. I think there are already optics packages for Octave available. The example on that site shows how you'd set up each matrix. I made a version in Javascript, but it'd be just as easy to do in Octave and you could even plot what you need from it.
 




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