DIY SWIR/NIR source from a halogen lamp

[DaJMasta]

This forum has seen some SWIR and NIR threads, so I assume this is the best place to put it.  I designed a printable lamp housing for a reasonable power selectable band source made from a printed box, a tungsten halogen lamp, a longpass filter, and it seems to work well.  The box is sized and designed around a 10W, 12V halogen lamp - the heat output of halogens is high, so there are lots of ventilation slots, but they angle away from the front face with the filter, so a minimal amount of visible/out of band light will show on the front face target.  I used some reflectors found on ebay, but there is probably a good variety that will work, and reasonable gauge solid core wire makes for a reliable lamp mount that can be bent to focus against the reflector in back.  The optical filter can be selected for usage (a tungsten halogen lamp is a very broadband source), and is a standard 50x50x2.5mm size (2" square) that is often available on the used market.

https://www.thingiverse.com/thing:4758234



For the pictured box, I used a 2800k halogen lamp (lower color temperature means a larger portion of the total emission below the visible band), a reflector off ebay, and a Schott RG1000 filter (1000nm longpass).  The filter will likely be the majority of the cost of the whole thing.  I screwed on the reflector with M3 machine screws and nylon spacers, then I stripped the solid core wire and bent it approximately in place, securing in two places with zip ties, so that I could solder the lamp in place to the wires.  Then I made sure to clean the lamp with isopropyl alcohol, slid the filter into the front slot, and pressed the two lower halves together.  A couple of nuts and bolts, one on either side of the bottom, help keep the press fit parts hold the wires in place better, then you press fit the top piece on it.  The bottom has a 1/4" 20 TPI thread built in for a standard camera threaded mount.


(the room is much darker than the high gain of the visible camera makes it look)

The results are good!  You get stripes of unfiltered light facing to the side and back, but looking at the face of the light you only get what comes through the filter, I've got a set of cameras setup for multiband visualization and you can see that the RG1000 passes as expected - the NIR camera can see it in its reduced sensitivity region (sensitive to about 1150nm, I figure), whereas the SWIR camera sees a bright light.  You can see a tiny bit of UV through the slots, but I think being low color temperature and probably a standard glass lamp (rather than quartz glass), there is little UV emitted by the lamp used.

http://medpants.com/ee/SWIR%20Source%20SWIR%20only.jpg

(the plastic magnifying glass passes SWIR just fine!)

[Fraser]

Nice project 

Only one safety related comment though. Halogen lamps are well known for the high temperature at which they operate. Such is necessary for their correct operation to preserve the filament. As such care is needed when using Halogen lamps near plastics. My Tiertime UP! Box 3D printer uses fire retardant 3D printed parts for its extruder head covers because Tiertime warn that normal 3D ABS burns easily and is a potential fire risk. I know you are being careful and will not leave the lamp unattended whilst operating, but do keep an eye on it as if the top casing melts down into the Halogen lamp things could get ‘interesting’ .

Lamp houses for Halogen lamps used with Microscopes use metal, ceramic and heat resistant plastics, and for good reason.

Fraser

[Ultrapurple]

That's an excellent piece of work, and a very useful design for the community.

Thank you also for posting images made at so many different wavebands. I see I'm not the only person who has LWIR-to-UV capability!

Bearing in mind what Fraser said, is it worth considering adding some simple thermal monitoring or protection in the housing (eg a resettable thermal fuse)?

[DaJMasta]

Thermal fuse would be pretty easy to put up top, I left it going for a few hours and examined it with a thermal camera too as I figured that was the risk with it, and with a 10W bulb it seems to be fine - no softness or drooping in the top plastic and no obvious hotspots that are too high externally.  The center of the filter window has a similar hotspot, and as expected, the wires coming through the base of it, but at least provided that the lamp doesn't move from its set position it appears to be fine for operation at room temperature.  I wouldn't put it in a high vibration environment or anywhere particularly hot, though.

Aside from making it larger or having a thermal cutoff, I'm not sure what could be done to make it safer (I guess underdriving the lamp would do it too).  I had thought about looking for an IR reflective paint, as it may give a bit more output from the front window as well, but while I have the equipment to test paints for their performance, I don't know of ones that really advertise it and don't really feel like taking the time  Too many other projects on the way.

[bap2703]

Lamp houses for Halogen lamps used with Microscopes use metal, ceramic and heat resistant plastics, and for good reason.

Got one just next to me:


Interestingly the lamp is encased in a metal shield.
The vents are only there to cool the casing, but no external air flow is hitting the lamp itself.
That might also help with the temperature stability of the lamp .

[mjs]

Nice one, where did you buy the RG1000 and how much did it cost ? I should do one, too!

Regarding light output, the relative IR/VIS output is indeed higher at lower temperature, but the absolute IR output is higher at higher power/temperature. Of course the poor filter needs to absorb and turn into heat all that VIS part and needs to be cooled well.

Have you measured the output spectrum ? I did some work with a slide projector and there was a clear dip at 1450nm or thereabouts - probably due to OH or some similar absorption somewhere. Exactly where I would have needed the light for water absorption measurements..

[DaJMasta]

I think both I used, an RG1000 and a Corning glass 2540 which was supposed to be equivalent, I got in boxed sets of several filters, so thankfully, less than normal!  I think you can get a 2"x2" RG1000 on the used market for somewhere in the ballpark of $30 or $40, so not cheap but not the same tier as brand new.

I haven't properly measured the spectrum, I think I have a spectrometer that can get to the near end of the likely output spectrum, but not really into the SWIR band, so the best I've got is the SWIR response, really.  I will have a look in MWIR sometime soonish, though, would be interesting if I could actually see "illumination" in that band, but I've only got the filter datasheet to go off of so far.


I've got a monochromator with an output issue (I think PMT driver electronics), but maybe I can get around to fixing that up and seeing if it can reach that far down at some point.

[Fraser]

DajMasta,

Please be careful if you intend to expose your MWIR camera to the output of a Halogen lamp. I have been advised that such a light source can easily damage the MWIR detector array

Fraser

[DaJMasta]

The intention was to see if I could illuminate a scene with it, but noted I will be sure to be careful, haven't done much straight on illumination except for low power check sources at a distance with other cams.

[_Wim_]

I haven't properly measured the spectrum, I think I have a spectrometer that can get to the near end of the likely output spectrum, but not really into the SWIR band, so the best I've got is the SWIR response, really.  I will have a look in MWIR sometime soonish, though, would be interesting if I could actually see "illumination" in that band, but I've only got the filter datasheet to go off of so far.

Nice project! That quite a big range to measure, and I thinks performance will be pretty close to the theoretical performance by subtracting the filter response from the halogen bulb response. Attached the response of 2 typical long pass filters, and the response of a typical halogen bulb. So short wavelength behavior will be dominated by the filter, and the long wavelengths by the bulb type and partly by the filter also.

Did the ebay seller have more of those reflectors? They are a nice format to play around with by my Ebay search came empty handed.

[DaJMasta]

Not really cheap, but these are the ones I used and they do seem to be pretty well made: https://www.ebay.com/itm/271451806335

[_Wim_]

Not really cheap, but these are the ones I used and they do seem to be pretty well made: https://www.ebay.com/itm/271451806335

Thanks, that one did not show up as he is not shipping to Belgium (stupid Ebay search  ), but I sent the seller a message to see what is possible. 

[Ultrapurple]

...  (stupid Ebay search  ), ....

Have you ever tried searching for something on Amazon?

[DaJMasta]

Ugh, parametric style searching on amazon is as worthless as it gets.  Sellers can and do offer their items in whatever category and specification they like, even when it's wrong or when it overlaps hugely with a category in an entirely different section, but it doesn't matter either because amazon will suggest whatever's popular or promoted that's slightly related to your search terms.  You can search for something hyperspecific and if amazon understands at all what you may be looking for, most of the stuff that comes up is specifically not what you were looking for.

At least with ebay it doesn't add items with similar terms in the title to your search without any way to disable it, so if you pick the right term, you can filter things pretty well.

[_Wim_]

Have you ever tried searching for something on Amazon?

Yes, I do not do that any more. Ali-express is also not the best. I fail to understand how it is possible big companies cannot make such an important feature for their business better 

[_Wim_]

Not really cheap, but these are the ones I used and they do seem to be pretty well made: https://www.ebay.com/itm/271451806335

Just bought a couple! Seller changed his listing to worldwide shipping after my request. Indeed not the cheapest, but the tabs on the reflector make installation and alignment so much easier compared to the typical reflectors with only rounded surfaces. 

[Ultrapurple]

I fail to understand how it is possible big companies cannot make such an important feature for their business better 

Simples: if you search for "10k 1/4W 1% metal film resistor" they hope you'll also buy, on impulse, a tacky garden ornament, a book on perpetual motion techniques and a monthly subscription for tinned unicorn food.

The problem is, it does actually work (as my somewhat rotund pet unicorn will testify). 

[Ultrapurple]

Not to be confused with this:



(I bought one of these and gave it to my then-teenage daughter, who was very into unicorns - much hilarity ensued)

[lukier]

Nice project!

Could you tell a bit more about the cameras, especially SWIR and UV ones? These seem extremely rare.

[DaJMasta]

The SWIR camera has a couple threads about it floating around this section - an Electrophysics 7290 (though the older non-A version).  It was designed in the late 80s if I remember right, but uses a Vidicon tube, so it's all analog adjustments and you run into a bit of image retention on the tube and quite a bit of ghosting from the slow decay response of the phosphor used (lead sulfide).

The UV camera in this example is actually a standard camera - a Watec WAT-902H Ultimate - with the exception that it has a very high gain, low noise mode to see in very low light conditions.  The UV response of a standard CCD usually falls off pretty fast, but thanks to like 50dB of gain, you can get a usable image down to 300nm or so provided you filter the input sufficiently.  I'm using a Hoya U340 and Midwest Optical BP550 in tandem to get out all the visible and IR components in this case.

In proper UV cameras that can sense into the deep UV with reasonable sensitivity, there are some EMCCD and other specialty processes that can directly sense the short wavelengths, but most less expensive (still not cheap) options involve a standard back illuminated sensor with a coating of lumigen, so those deep UV wavelengths make the coating fluoresce and show up as an image.  Something like the ICX407BLA sensor is an example of that technique.

[Lambda]

Hello.

Just a short passage for saying thank you, DaJMasta, for this very interesting and instructive thread!

And just for illustrating your last paragraph, some interesting links on DIY UV viewer using the principle of down conversion UV -> Vis.

these DIY projects are using image intensifiers or conventional cameras (Mintron, by the way, close to your Watec, in a family "point of view"), both equipped with converting front opticals elements and UV pass/Vis blocking filter...

https://hackaday.com/2016/07/06/seeing-the-truly-invisible-with-diy-shortwave-uv-imaging/

http://uvirimaging.com/2016/07/03/diy-shortwave-uv-image-converters-for-solar-blind-and-ruvis-imaging/

Best regards.

Stéphane

[lukier]

The SWIR camera has a couple threads about it floating around this section - an Electrophysics 7290 (though the older non-A version).  It was designed in the late 80s if I remember right, but uses a Vidicon tube, so it's all analog adjustments and you run into a bit of image retention on the tube and quite a bit of ghosting from the slow decay response of the phosphor used (lead sulfide).

Ah very nice camera, pity these are so rare and expensive on ebay.

The UV camera in this example is actually a standard camera - a Watec WAT-902H Ultimate - with the exception that it has a very high gain, low noise mode to see in very low light conditions.  The UV response of a standard CCD usually falls off pretty fast, but thanks to like 50dB of gain, you can get a usable image down to 300nm or so provided you filter the input sufficiently.  I'm using a Hoya U340 and Midwest Optical BP550 in tandem to get out all the visible and IR components in this case.

In proper UV cameras that can sense into the deep UV with reasonable sensitivity, there are some EMCCD and other specialty processes that can directly sense the short wavelengths, but most less expensive (still not cheap) options involve a standard back illuminated sensor with a coating of lumigen, so those deep UV wavelengths make the coating fluoresce and show up as an image.  Something like the ICX407BLA sensor is an example of that technique.

Ah so just filters. I thought you have the latter approach. I like the lumigen coating idea, wonder if this could be done "at home" to some cheapo back illuminated sensor (like OmniBSI) - a bit like scintillators for x-ray.

Thanks!

[DaJMasta]

It very well may be, but it may be difficult to apply the right thickness as to prevent blocking visible light or blurring the image - I imagine the finish has to be pretty smooth to keep from scattering the UV when it hits it.  There are some other detector constructions that seem to be able to see UV, and just a back illuminated standard detector may give reasonable UVA performance.  Not like there are tons of things to image in the shorter wavelengths of UV as they're not really safe to be around the illumination sources and then you start generating ozone or just dissipating in open air as the wavelength gets shorter.

[_Wim_]

Ideal thread to show off my “new” tool I managed to get working today  . I bought this one on Ebay after seeing it listed for a couple of months with nobody buying it, I thought it was worth the gamble:

https://www.ebay.com/itm/CONTROL-DEVELOPMENT-OSC-SU256LX-1-7T1-250-9-1-7-3-13-100um-Spectrophotometer-/184614212682?hash=item2afbdd544a%3Ag%3A9-wAAOSw5SRfFcNt&nma=true&si=XDit031vmfz5Vfp3q9pQke6Mh2Y%253D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

I spent quite a while looking for the software & drivers, but found them in the end. Next challenge was to find a pc with an ISA slot and sufficient room for such a big card. Luckily they had some old industrial pc’s at work collecting dust,  so I brought one of these home. After installing window98 & VNC server, I can now remotely control this PC.

This card has a 256 peltier cooled ingaas array, allowing spectrum measurements from 900nm to 1700nm. My version is cooled to 0°C. Is was sold in 2001 for the “affordable” price of 9995$ (see flyer I found online in my search for the software).

As a first test, I thought I would measure some of the halogen sources I have:
-   12V 35watt MR11 halogen bulb from ali-express (https://nl.aliexpress.com/item/32891567396.html?spm=a2g0s.9042311.0.0.27424c4d7XRuq0 ) I bought these because this had no glass cover expecting less issues whir their response. I was wrong apparently… 
-   12V car halogen bulb.
-   Avalight HAL connected using a 400µm VIS/IR fiber
-   Light source that came with the control card connected using the same 400µm fiber

Black body calibration was performed using the light source that came with the card.

Very satisfied with my purchase! 

[lukier]

This card has a 256 peltier cooled ingaas array, allowing spectrum measurements from 900nm to 1700nm. My version is cooled to 0°C. Is was sold in 2001 for the “affordable” price of 9995$ (see flyer I found online in my search for the software).

Very interesting! I didn't know how it was done in the past, sounds expensive indeed. I do have some experience with more modern version:
https://www.element14.com/community/roadTestReviews/2322/l/dlp-nirscan-nano-evaluation-module-review
(this is also quite clever use of a DLP)

I do have some Ocean Optics S2000 spectrometers, but still haven't managed to find time to make USB interface for them 

-   Light source that came with the control card connected using the same 400µm fiber

Black body calibration was performed using the light source that came with the card.

Do you know what is the light source inside?