Author Topic: ZnSe lenses on Ebay  (Read 8780 times)

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Offline havewattwilltravel

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ZnSe lenses on Ebay
« on: August 16, 2018, 06:59:03 pm »
So what's the story on the ZnSe lenses on Ebay, specifically for augmenting cameras like the Flir Ex for PC board work?

Specs are comparable across a broad range of prices, except for maximum wattage.

Is the $80 200W US lens twice as good as the $15 100W Chinese one?
(The $150 US lens actually has better specs.)

My experience from Chinese products is that "consistent quality" is a Japanese concept, and the Chinese hate the Japanese, so that the variations from the same supplier for the same product are as much as the variations between suppliers.

In the end, it's all a crap shoot and the house usually wins.
 

Online Fraser

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Re: ZnSe lenses on Ebay
« Reply #1 on: August 16, 2018, 07:49:01 pm »
Most, if not all, ZnSe lenses manufactured for laser engraver use are not intended to produce a low distortion optical image when used in thermal imaging. Reputable manufacturers of these lenses even state this on the datasheet.

There are high performance ZnSe lens elements from companies such as Edmunds Optics who specify the elements performance.

In practice, almost any ZnSe lens used in laser engravers will work as a decent enough close up lens. The low resolution of the thermal cameras is often forgiving of the lesser optical performance of such lenses.

I suggest you purchase a suitable lens from China for around $20 and see if it meets your needs. A high optical performance ZnSe lens with low distortion will cost you around $150 in the USA.

Fraser
« Last Edit: August 16, 2018, 07:50:36 pm by Fraser »
 
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Online Fraser

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Re: ZnSe lenses on Ebay
« Reply #2 on: August 16, 2018, 07:53:38 pm »
Here is a reputable lens manufacturer. Note their comment in such lenses being suitable for non critical imagine quality applications.

http://www.iiviinfrared.com/CO2-Laser-Optics/plano-convex-lenses.html

The same company can supply excellent optical quality lenses for IR imaging using various materials, including ZnSe.

http://www.iiviinfrared.com/IR-Thermal-Imaging-Optics/ir-thermal-imaging-lenses.html

It all comes down to the actual imaging quality required.

Fraser
« Last Edit: August 16, 2018, 07:57:55 pm by Fraser »
 

Online Fraser

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Re: ZnSe lenses on Ebay
« Reply #3 on: August 16, 2018, 08:02:13 pm »
Note. Power rating of the lens has little to do with optical quality. Transmission is never 100% so losses have to be managed in the lens design when used with a high powered laser.

Fraser
 

Offline eKretz

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Re: ZnSe lenses on Ebay
« Reply #4 on: August 16, 2018, 08:12:51 pm »
I would watch eBay and any other sites for germanium lenses too. There are bargains now and again. I managed to snag a huge coated germanium close-up lens that fits snugly right into my rubber focus grip on my E40 for peanuts.
 

Online Fraser

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Re: ZnSe lenses on Ebay
« Reply #5 on: August 16, 2018, 08:17:13 pm »
With Germanium lenses, just be sure they are coated for LW and not SW/MW as a SW or MW only lens is useless on a LW camera.

Fraser
 

Offline DaneLaw

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Re: ZnSe lenses on Ebay
« Reply #6 on: August 16, 2018, 08:19:51 pm »
I would watch eBay and any other sites for germanium lenses too. There are bargains now and again. I managed to snag a huge coated germanium close-up lens that fits snugly right into my rubber focus grip on my E40 for peanuts.
A picture and a price would go a long way as the concept of "huge germanium lenses" varies greatly from one person to the next and not least "I got it for peanuts" which also varies a lot from one to the next and difficult to put into perspective. 

--

I pick one of the ZNSe a few months back, it costed 8bucks (USD) delivered with a focal length listed at 50mm.

I get this level of makro from a budget-viewpoint.(Seek Pro FF iOS 290USD + 8USD ZnSe FL 50mm)



Item..




« Last Edit: August 21, 2018, 11:41:23 am by DaneLaw »
 
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Offline havewattwilltravel

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Re: ZnSe lenses on Ebay
« Reply #7 on: August 16, 2018, 09:17:01 pm »
I'm not sure which line on their website tweaks me more, that their lenses are available in "diamond-like coatings" or that most of them are thorium-free.

Now I'm not sure whether to take out a mortgage or buy a Geiger counter before continuing.
 

Offline eKretz

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Re: ZnSe lenses on Ebay
« Reply #8 on: August 16, 2018, 09:31:47 pm »
Sure, no prob. Lens is about 60mm O.D. and focal length around 100mm. Price was $40 + shipping through an eBay "best offer." Don't have any sample images right now, they're still in the camera. Will post a few later.
 
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Offline CatalinaWOW

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Re: ZnSe lenses on Ebay
« Reply #9 on: August 16, 2018, 09:57:23 pm »
When I retired several years ago "diamond like coatings" was an attempt at accuracy in describing vapor phase deposited polycrystalline diamond coatings.  The processes used didn't result in diamond crystals even approaching the coating thickness, but they were harder and more wear resistance than many other options.  Similarly thorium flouride is used in some coating designs.  The quantities used are minuscule and thorium is not highly radioactive.  The thorium risk is almost entirely in the manufacturing process, with very little risk at the point of use of the optics.   Some sources estimate that the radioactive dose from using these lenses is about 1/600 of the natural background level everyone is exposed to.

A knee jerk reaction against these terms will cause you to miss some good deals and will not protect your health in any measurable way.
 

Offline eKretz

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Re: ZnSe lenses on Ebay
« Reply #10 on: August 16, 2018, 10:26:41 pm »
The coating is "diamond-like carbon" and it is probably one of the most durable coatings there is.  However, it doesn't have the highest transmission of the available coatings. I read a quite interesting university study of some of the iterations of DLC as they were created, they have got it refined to a pretty high level nowadays.
 

Online KE5FX

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Re: ZnSe lenses on Ebay
« Reply #11 on: August 17, 2018, 12:38:59 am »
Hacked E4 (320x240):



Hacked E4 with lens from https://www.ebay.com/itm/321078811086 (19 mm ZnSe, unfortunately I don't recall the focal length):



The smaller components in this screenshot are 0402 (US).

Checked lens with Geiger counter with alpha window, no radiation detected.  :o
 
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Offline havewattwilltravel

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Re: ZnSe lenses on Ebay
« Reply #12 on: August 17, 2018, 03:42:40 am »
Thanks for posting those. That's a really impressive level of detail. It's also very moving, in a way, to be able to see the heat rather than just running an equation that predicts it.

Next question: what about meniscus versus plano-convex? Is the former better than "a type of mudbrick used by the ancient Sumerians" (another definition according to Wikipedia)?

With a high focal length (50mm-100mm), I'd be tempted to integrate the macro lens mount into some kind of adjustable tripod or camera holder. While I can't dance, I can shake. Given that my normal photography is at best impressionistic, I doubt if I could create anything more than orange smears if holding the camera in one hand and a board in the other. Kudos on making your dexterity roll.

Perhaps it's a good enough excuse to buy an arduino CNC board to scan the target...oh, such potential for wasting time and money!
 

Online Fraser

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Re: ZnSe lenses on Ebay
« Reply #13 on: August 17, 2018, 10:50:02 am »
Think of the close up lens as little different to wearing reading glasses. It just converts the focal length. With reading glasses we tend to see meniscus lenses used and they would be my first choice. Sadly such lenses are not usually used for laser engravers so they are less common and more expensive. Optical performance will, however, be better. Laser engravers use Bi-Convex and Plano-Convex. Both work fine for Close-up PCB inspection.

For greater lens performance, you sadly have to spend a lot more money. If a cheap ZnSe lens is scratched or damaged, it is no great loss and easily replaced. The ZnSe lens also acts as a lens protector for your very expensive thermal camera lens. When working very close to a PCB, say 25mm, it is easy to knock into a sharp edged heatsink or chassis part.

Fraser
« Last Edit: August 17, 2018, 05:47:02 pm by Fraser »
 

Offline eKretz

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Re: ZnSe lenses on Ebay
« Reply #14 on: August 17, 2018, 07:55:19 pm »
It really isn't difficult to get clear images with the close-up lenses handheld. The lenses on these cameras are almost always something like f/1 so they don't need much time at ALL to take a picture. On a very far subject with a tele lens you might want to use a tripod.
 

Offline eKretz

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Re: ZnSe lenses on Ebay
« Reply #15 on: August 18, 2018, 11:46:55 pm »
The lens I posted a photo of above is a meniscus lens. Here are a couple images form my E40, the first image with the stock lens focused as close as it can manage, and the other of the same board with the close-up lens as close as it can focus. Do note that I didn't bother squaring the lens with the subject, so focus is only optimal in the area of interest due to very shallow DOF.
« Last Edit: August 18, 2018, 11:48:36 pm by eKretz »
 
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Offline DaneLaw

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Re: ZnSe lenses on Ebay
« Reply #16 on: September 17, 2018, 02:56:34 pm »
Hi guys..

Im a littlse unsure, hence ZnSe and GaAs lenses and focal length..
Usually its ZnSe there are the most affordable alternatives..particularly the orange china ones, hence the more yellowish socalled USA-ones there seems to have better purity.
Already got a ZnSE at 12mm 50mm focal, and would like some more lenses and not least in different material like GaAs and perhaps ¨different focal length sizes to see charstica and pro and cons and perhaps incoherent with each other.

Got an offer for 20mm GaAS with a focal length af 10.1cm. (4") 15USD delivered but I reckon I could change it to 1.5" 3.8cm if that was a no brainer for macro on IR, but Im unsure about GaAS as a whole..
when its macro you have in mind, then it would make the most sense to go for the smallest focal length, correct? as a supplemented macro-lens like the above with a focal length at 10.1cm 4" would not be much more then what the native thermal lens in the Seek pro can perform in the closest turnpoint by itself' or are there some benefits with going for higher focal length and perhaps each fitted lens leverage each other...

How does a GaAS lens stack up as an macro lens in regards to ZnSE? I can see the that Gallium Arsenide GaAS transmits over 40% between 2-15µm while ZnSE about 50% between 0.4 -12μm before dropping off to zero transmission around 15μm and Germanium transmits over 45% between 2-14μm.
So GaAs is the lowest of the bunch, but how does it hold up in practice.
Thx for any info..
 

Online Fraser

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Re: ZnSe lenses on Ebay
« Reply #17 on: September 17, 2018, 03:35:19 pm »
A good quality ZnSe or ZnS lens element is an excellent performer. Excellent transmission but a little soft so easily scratched.

GaAs also transmits well at LW and is a harder material, so less easily scratched.

With your transmission figures you need to consider the AR coating applied to the lens surfaces. With no AR coating your figures are nominal, but you should be looking for lenses that are AR coated for LWIR as their transmission is far higher.

I have both GaAs and ZnSe lenses and I recommend ZnSe for your intended use if suitable AR coated Germanium is not available or too expensive.

For info ZnSe and ZnS are to be found in professional lenses but normally behind the protection of a Germanium Objective (not in every case though)

Remember that thermal cameras are relatively low resolution devices and more forgiving of less than perfect optics in many cases. PCB inspection often does not need perfect lens performance due to the nature of the targets.

Using the original camera lens set to close-up focus, if possible, is better than using a supplementary lens. You could even consider a close-up extension tube for the camera lens to provide closer focus ? It need not be very long, a few Millimeters at most. The SEEK lens mount is not that easy to work with however.

Fraser
« Last Edit: September 17, 2018, 04:21:22 pm by Fraser »
 
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Offline DaneLaw

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Re: ZnSe lenses on Ebay
« Reply #18 on: September 20, 2018, 07:21:55 pm »
Thx for your feedback..Im im not sure what kind of coating this one carries.it states 0.5% pr surface for AR coating.
Most of these lenses are not headed for thermal infrared pictures but mostly centered to focal C02 lasers and the sellers, sadly don't know jack, as these usually just wholesalers, placing an order at third party on my behalf.



But its a 20mm GaAs at 15 USD delivered with a focal length at 4" 101.6 mm.
I can see he also has them in 1½" and 2" and 3" focal length..(so I reckon I could change it for a lower focal length if that was the obvious sum)
and I already have a ZnSE (cheap China orange version in 50mm FL and I reckon for variety purpose I would mix it up with a wider FL to see if there was any gain there, but on the other hand 101.5mm focal length would more or less be around the native lens in Seek pro as it seems to focus down to relative 10 to 15cm at closest point, so any gain for thermal-macro on a GaAs at 10.16CM FL?' here it would likely make more sense to go with the smallest focal length possible on these GaAs lenses' or ??)

But been pretty impressed with my cheap 8USD 50mm focal length ZnSE lens and its macro-ability and I love to fool around with wavelengths in different laser'diodes and here many of these lenses have wicked abilities to pass some wavelength and block others and so forward, not least ZnSE there are willing to pass high NM green and up, like yellow and red etc, but completely blocks blue and violet and partly low'end'nm green wavelengths...
https://imgur.com/a/xipfTdn

What you reckon' any info to sense if this GaAs lens will be doable to thermal macro?? or is it a luck of a draw if it got the useable LWIR coating but then again 90% clear aperature 10.6um.
« Last Edit: September 20, 2018, 07:35:49 pm by DaneLaw »
 

Online Fraser

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Re: ZnSe lenses on Ebay
« Reply #19 on: September 20, 2018, 07:39:38 pm »
That lens will work fine

Fraser
 

Offline Vipitis

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Re: ZnSe lenses on Ebay
« Reply #20 on: September 20, 2018, 09:17:38 pm »
Can you share the sellers eBay shop? Because Laserlands was previously mentioned as reputable but has no lenses offered the last time I checked.
 

Offline DaneLaw

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Re: ZnSe lenses on Ebay
« Reply #21 on: September 21, 2018, 01:16:07 am »
 

Offline Pinkus

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Re: ZnSe lenses on Ebay
« Reply #22 on: October 04, 2018, 09:28:26 am »
May I ask your opinion?
I decided finally to get a ZnSe lens for my Exx to allow a closer focus / higher magnification. However I do not need a huge magnification, 2x is fine for me.
I am afraid a 20mm lens might be not large enough, as the original lens is already approx. 25mm (see pic attached). A 25mm lens probably gets a sharper image at the corner.
Thus I think a 25mm lens with a focal length of 100 to 150mm would be correct.
Would this lens here https://www.ebay.com/itm/152310493227 with 25mm diameter and 101mm focal length be OK?  33$ incl. shipping sound like a decent price for a 25mm lens.
Thanks!
 

Online Fraser

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Re: ZnSe lenses on Ebay
« Reply #23 on: October 04, 2018, 09:51:57 am »
I have not used a ZnSe laser lens on my Exx series as I have larger diameter Inframetrics Germanium lenses. You are quite correct, a 20mm diameter lens would appear too small for use with an Exx series camera. You need to consider the objective diameter plus the FOV. A lens of equal diameter to that fitted in the camera would need to be positioned very close to the objective to reduce distortion and vignetting. A risky practice as physical contact with the cameras objective is highly undesirable ! Even a 25mm diameter lens may not avoid vignetting due to the cameras FOV. It would need to be close to the objective, as stated. My supplemental Close up lenses are 50mm diameter but such are hard to find at reasonable cost, even if ZnSe rather than Germanium.

You may have to live with some vignetting, but that may still be acceptable for PCB inspection.

Fraser

« Last Edit: October 04, 2018, 09:53:51 am by Fraser »
 

Offline Pinkus

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Re: ZnSe lenses on Ebay
« Reply #24 on: October 04, 2018, 10:40:57 am »
Thanks Fraser,
Indeed, lenses with a diameter of 38mm or 50mm are quite expensive.
I now just bought the 25mm lens with 101mm FL and will report the results after arrival in a few weeks.
In the meantime I have time to plan of a decent lens holder for the Exx.
 
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