Thermal cameras with decent low level control? - Page 1
Forum section: electronics / general

author: Topcode
author_rank: Newbie
timestamp: February 02, 2025, 09:20:15 am
content: I have only just dabbled in thermal imaging, with a cheap MLX90640 hooked to an ESP32 with a somewhat custom written driver that barely works. However, it gives me rather good low level control. But I really want an upgrade.I have also just been barely dabbling into NIR astrophotography. It’s fun, but I yearn for more bands. I do plan on using my NVD to push a little further than my sensors can (they aren’t sensitive past about 1.1um) but even that is only so much.Naturally, the conclusion is to buy a thermal camera which will give me good low level control and so I can use it for astrophotography too. The tiny1-c looks good (very cheap), but it doesn’t look like it gives really any control, such as doing a longer exposure. Or getting raw sensor data. Two things that are a necessity for astrophotography use.So I am unsure what to go for. But I do see a lot of productive conversation about thermal cameras here, so I figured I would make an account and see what you guys think. The cost I can spend is small, I would like to spend less than 800 dollars on a thermal cam, because my normal Astro cams are still gonna be a priority and I just think this will be a cool addition to my setup, particularly since I should be able to simultaneously image one object by using a germanium window to split the IR from the visible.

author: Bill W
author_rank: Super Contributor
timestamp: February 02, 2025, 05:39:02 pm
content: For astro, be aware of the kind of images I got with a FlirOne (12µm pixels) and a stupidly huge 150mm f/1 lens ...http://www.fire-tics.co.uk/project4/lenses.htmI still haven't put that on an Argus system though - where I'd be able to get calibrated data out (1 bit = 1/32 °C).Hopefully Fraser will add the kind of controls some of his camera collection offer (retail $80k that he gets for $100 off eBay with his miraculous powers)On the commercial cores side, they are pretty much closed box even with the factory software, and most will be tied into a 60Hz/30Hz refresh too so limiting maximum integration time. You won't get minutes of integration anyway as thermal leakage then dominates - standard 8-14µm bolometers are not photon accumulatorsAnything 'old' will be going up in pixel size too, so a Raytheon BST had 50µm pixels and the factory software although available doesn't do a whole lot.Bill

author: Topcode
author_rank: Newbie
timestamp: February 02, 2025, 06:15:18 pm
content: Quote from: Bill W on February 02, 2025, 05:39:02 pmI had actually come across a post linking those images already, I’m assuming those are straight off the camera. Of course, since I’m planning on imaging deep sky, with a much slower telescope, I won’t get results that good.Minutes of exposure would be great, but all I’m really after is like, one or two seconds. Which should be enough. In terms of thermal noise, I’ve heard mixed things about cooling. I have made custom cooling systems for all my astronomy cameras so far, so I was planning on going ahead for this, but I don’t know how much efficiency you will get. People have warned about how the camera can’t self calibrate too far off ambient, which makes sense to me, as in astronomy calibration frames are temperature dependent, but if I can get the raw data, then I can take my own calibration frames. I also don’t really need to calibrate it, unless amp glow is a super big issue for thermal sensors. My scope dithering and KS stacking should work well enough on fixed pattern noise even without calibration.

author: Fraser
author_rank: Super Contributor
timestamp: February 02, 2025, 08:07:38 pm
content: The whole topic of thermal astronomy is a bit of a nightmare and I will précis the issues you face here…..1. Most general use thermal cameras are now microbolometer based and these are not best suited to deep space observation as they are very noisy and not that sensitive (no matter what the sellers tell you)2. Most general use thermal imaging systems operate in a configuration guaranteed to produce acceptable imagery for the intended application and, even if they have manual configuration modes, they do not offer deep sensor array adjustments to peak the imaging performance in a particular application. Such fine tuning is normally only available to the manufacturer during production, and even then, not the sort of adjustments that you are looking for.3. Science thermal imaging cameras are intended to be used in science and demanding industrial applications. These cameras differ from general use cameras in that they are often intended to be highly configurable, may be user calibrated and offer capabilities not found in less advanced general use camera platforms. You are able to change detector biases and integration times which would be important in your case. These cameras are often cooled using either Liquid Nitrogen or a Sterling Mechanical cooler with the sensor array operating at 77K (-196 Celsius). These cryo cooled sensor arrays have superb internal noise levels making them perfect for low noise imagery of relatively cold targets. The down side of Science type thermal cameras is their cost. New prices are astronomic ! My FLIR SC4000 is only QVGA yet it cost its original owner £150K as it is a special model that covers SWIR and MWIR wavelengths. The cooled cameras tend to use photon detectors as their sensors, so are perfect for your application. The FLIR SCxxxx series of cameras has been attached to some truly impressive cooled long range telescopes. I bought mine when the owners company went into liquidation so I got an extraordinary deal on it. That was a once in a lifetime event though. For what you are wanting, you will need to look for used Science thermal cameras and expect to pay a considerable sum for such as they are both rare and sought-after. Sadly there is no ‘middle ground” between general use thermal cameras and the very expensive science thermal camera.4. Optical resolution is a killer in your application. Most affordable thermal imaging cameras, even the general purpose models, will have less than 640 x 480 pixels, with 320 x 240 pixels considered ‘decent’ for many applications. Sadly such low pixel counts means relatively poor IFOV, especially when dealing with targets located at a long range in space. Huge magnification is needed from the optical system if any detail of the target is required. To detect a thermal target using thermal imagery normally requires that the target illuminates at least 4 pixels, with 9 being better. This avoids the cameras internal noise or noise reduction processes hiding the target from view. Computer aided image enhancement and target detection will help with this problem but ask yourself what the point would be of capturing a target that only illuminates so few pixels (or even a single pixel) as no detail will be discernible and path losses make accurate temperature measurements likely impossible.5. Telescope (optical system) thermal contamination is a problem when building a deep space thermal telescope. The body and parts of the telescope can create so much thermal noise as to mask distant targets in space. Some long range telescopes are actively cooled to reduce these levels of thermal contamination but there are limits to what can be achieved. A telescope operating in the Vacuum of space with effective sun shields has a distinct advantage over an Earth based telescope.6. Thermal sensitivity is a problem that faces anyone wishing to image distant targets with thermal cameras. The microbolometer is not the best when it comes to low noise and thermal sensitivity in its unprocessed use. Cooled cameras are very low noise and capable of very good thermal sensitivity. Sadly even with excellent sensitivity the camera is hampered by the performance of the optical system. Even ignoring the thermal contamination issues of the telescope, there is the speed of that optical system. A slow optical system could destroy the advantages of a very sensitive camera attached to it. The energy has to get out of the optical section and to the detector pixels if the camera is to have any chance of processing and displaying an image. For deep space work, the telescope would need to be of very high quality and this means very high efficiency optical elements, be they reflective of refractive in nature. Surface mirroring is absolutely essential on reflector elements. No non-thermally transmissive materials can be in the optical path of the telescope for thermal imaging.From the above you might think that deep space thermal imaging is pretty much a lost cause for the amateur…… and, IMHO, you would be correct. Unless you have a significant budget and access to a very advanced thermal imaging camera and optical kit, you will likely be very disappointed with the results of your efforts in the thermal domain. As a learning excercise, it may prove useful, but in terms of ‘Bang per buck’ thermal imaging is an awful choice compared to visible light and NIR deep space imaging. Everything about thermal imaging is expensive compared to VL and NIR equipment.Now if you said that you wanted to image the Moon, that would be different. Because the Moon is a relatively large target in our sky, you can image it in the thermal domain ‘on a budget’ as has been previously discussed on this forum. A decent telescope with surface reflective optical elements and a QVGA microbolometer based thermal imaging camera can capture an image of the Moon. How much use that image may be is another matter though. Far more interesting images may be captured in the VL and NIR wavelength domains with relatively inexpensive camera and lens configurations.If you decide to pursue the thermal imaging of deep space targets, I wish you well, but your budget will need to increase if you are to have any chance of success.Fraser

author: Vipitis
author_rank: Frequent Contributor
timestamp: February 02, 2025, 10:30:29 pm
content: To add - there are several other threads on here with attempts, results and more links. There even is some posts on CN.You should also consider the atmospheric window, making lwir possible but mwir not so much.For ground based observation with microbolometer s, there is three research papers that use nearly commercial OTS cameras. One about the sun, using a 3m scope and some ND filters (as to not melt the camera). One about the moon and mars (they also have an observation of a star - not sure how? But they had a larger scope) and some observations during an eclipse I think. And finally there is an obscure one about daytime meteor and comments/satellites that can be observed. I don't have the links at hand and two of them aren't open access.So for deep space, I doubt it's possible. I tried to look for bright targets in the N-band (10.2nm +/- 3nm) and via a space based survey M42 came up. I haven't been able to see it using my cameras and a 150mm f/1 lens either. But I didn't have raw sensor data. so you will likely need to record a video and integrate that in post. As microbolometers don't function like a cmos camera by collecting charge, they are essentially like an array of variable resistors and you read those out. Reading out even introduces thermal noise.Good luck, and search around for older threads, plenty of links with encouragement.

author: Fraser
author_rank: Super Contributor
timestamp: February 02, 2025, 11:16:15 pm
content: https://www.axiomoptics.com/blog/the-differences-between-swir-mwir-and-lwir-cameras/https://syronoptics.com/blogs/technical-article/what-is-the-mwir-atmospheric-window?srsltid=AfmBOoqcVap2qsfApedp0TcTKQD0Zb-bJMDWMwc9Kqk73J124_YBDcPr

author: Topcode
author_rank: Newbie
timestamp: February 02, 2025, 11:45:06 pm
content: Quote from: Vipitis on February 02, 2025, 10:30:29 pmWell, I wouldn't expect to see much with any camera set normally for taking video. For a while I did untracked astrophotography, you do not get much out of short exposures. Thats why I was hoping at least some exposure controlled cameras existed. It doesnt seem like they really do though. Although, I have heard about some sensors being 9fps limited, but it is unclear if those are binned data or if they are actually just sampling every 1/9th of a second.Quote from: Fraser on February 02, 2025, 08:07:38 pmI see what you are saying, but just because they all suck doesn't mean there isn't something that's the best. From what you are saying, something like a InGaAs would be my best bet because I can get something from like touptek for relatively cheap, tho more expensive than I would like. There is one thing you have wrong though, low resolution isn't really a downside here, big juicy light collecting pixels are a dream.So even if nothing is gonna be good, something has to be best. I looked around on eBay, found one kinda promising thing, an Electrophysics PV320LD, its an outdated technology (BST array), but it has raw data, is temperature controlled, and juicy roughly 50micron pixels, which actually would put my sampling dead on. Is that in the range of best options? I have no clue. The Tiny1c is a VOx microbolometer, which is supposedly better than BST, but the pixels are so small that it way oversamples me, and I dont think you can get raw data. Is that a better option? I also have no clue. I know that both are *bad* but, whats the least bad?And of course, I am sure I could get super lucked out at a government surplus sale (its amazing how cheap stuff goes for there) but obviously I cannot rely on that, even if I've gotten nice stuff before.

author: Fraser
author_rank: Super Contributor
timestamp: February 03, 2025, 12:33:53 am
content: The Electrophysics PV320LV contains a Raytheon Thermal Eye BST imaging core. Likely a 300 series module. These use a synchronised mechanical chopper wheel. Such a camera, or technology, would definitely not be my first choice for your application. The image noise levels are relatively high. BST is a technology that was promising but development was killed off by the Microbolometer. As such, Microbolometer technology has made significant performance advances over the last 25 years and BST, though capable, remains at its Year 2000 state of the art.The Tiny1C is fine for its intended market. It is a budget core with reasonable performance. It does not offer the tuning that you desire and relies heavily on image processing to produce an acceptable image. Such is not uncommon with microbolometers that use tiny 12um pixels. The 12um pixel really is pushing noise reduction to the limit due to the poor signal to noise ratio inherent in the design. A modified Tiny1C can image the Moon, no doubt about that, but it’s poor signal to noise ratio at its front end, combined with heavy handed noise reduction and video processing make it a poor choice for your more demanding application.Like you, I like nice BIG pixels to gather plenty of energy. Thermal imaging pixels have been getting smaller over the years in order to reduce silicon die sizes and so reduce costs. Smaller pixels do degrade the Signal to Noise ratio at the front end but ROIC technology and noise reduction techniques have managed to counter the image degradation to a large extent. That said, in highly demanding roles, the shortcomings of the small pixels can become evident. I personally like 35um and 25um pixels with the more recent 25um pixel cores benefitting from the noise reduction techniques being employed in 17um and 12um cores. That said, a core that is using 50um pixels is likely quite old technology unless stated otherwise. As such the older technology may not perform as well as the more developed modern smaller pixel cores such as those with 25um pixels. Whilst it is also true that VOx pixels provide a higher Signal to Noise ratio than A-Si pixels, great advances have been made in A-Si based microbolometers by companies like Lynred (was ULIS) to narrow the gap in performance between the two technologies. A-Si may even have equalled the performance of VOx by now. I have not kept up to date in that development path. Bill_W was testing some ULIS A-Si microbolometers in a Professional capacity at his workplace a few years ago. He may have some comment on VOx Vs A-Si in modern microbolometers.Fraser

author: Topcode
author_rank: Newbie
timestamp: February 03, 2025, 01:04:16 am
content: I did see some ULIS microbolometers on ebay, like a P0245C, but just the chip, no driver boards, datasheets, or even vague specifications, don't trust myself enough to figure that out so I had just counted them out, but if someone has experience maybe it would be possible to rig something up, if they are worth it.

author: phansel
author_rank: Contributor
timestamp: February 03, 2025, 02:05:03 am
content: DRS' Tamarisk320 has 14-bit parallel video output of the raw (FFC-corrected) pixel data. I've built a board that adapts that to USB over UVC via the CYUSB3014.FLIR's Boson series has 16-bit grayscale video output over UVC (USB).

author: Topcode
author_rank: Newbie
timestamp: February 03, 2025, 03:00:56 am
content: Quote from: phansel on February 03, 2025, 02:05:03 amIn a datasheet (well more of a promo sheet) It says it can do 9fps or 60fps, of course for my purposes 9fps is way better, but do you know if that is a setting that can be toggled or if its only built into specific models because of export, and cant be turned to 9fps from a 60fps model. And either way, do you know how the 9fps works, if its just averaging 6 or 7 frames, or if it is really sampling only 9 times in a second?Either way that is a nice lead.

author: Topcode
author_rank: Newbie
timestamp: February 03, 2025, 04:18:08 am
content: Ive looked around a flir stuff, and it looks like the flir lepton 1.5 and 1.6,(and UWFOV but thats more expensive) have removable lenses. I could probably get the lenses out of the other models, but, you know, don't wanna break stuff. Because its so cheap compared to other options, and I think it offers close to raw images, and the slightly bigger 17um pixels, I think it may be a good starting place to try with, leaving plenty of later budget down the road to upgrade. Only issue is, its really hard to find information about using the older models because now there are newer models, so I will have to probably do alot of wayback machine searching, or buy a 2.5 for like 70 bucks, and figure out how to get the lens out.What you people think about that idea?

author: phansel
author_rank: Contributor
timestamp: February 03, 2025, 10:30:17 am
content: Quote from: Topcode on February 03, 2025, 03:00:56 amNot sure, I have never used a 9 Hz core. I imagine they are e-fused permanently at the factory for export purposes.

author: Fraser
author_rank: Super Contributor
timestamp: February 03, 2025, 12:04:52 pm
content: The 9fps version of a camera is intended to meet export control regulations and is not normally for the purposes of frame averaging. In a 9fps/25fps camera core, the 9fps version sends the same frame 3 times to produce 8.33fps. There are techniques in the Industry where the microbolometer is read out at a higher rate than the system output frame rate in order to use the additional frames in a noise reduction process. Such detail would need to come from the manufacturer of a particular imaging core or camera however. The problem you face with any OEM provided image processing is that such processing may not be to your liking or compatible with your application. The RAW scene data coming out of a microbolometer requires basic video processing in order to be useable however.Lepton is an old core design and not one I would even consider for any form of challenging imaging. Bare microbolometers are basically paperweights unless you know an awful lot about designing the support electronics and firmware needed to create an imaging core.I will leave others to help you in your research into a suitable microbolometer based camera for your quest, but do manage your expectations to avoid disappointment.Fraser

author: Bill W
author_rank: Super Contributor
timestamp: February 04, 2025, 01:07:34 am
content: Quote from: Fraser on February 03, 2025, 12:04:52 pmSome of the early FLIR Tau based cameras DID just average down x4 from 30Hz - so were very laggy and I suspect added back the noise through the 'noise adding function' from back in E4 to E8 upgrade hack days.Hardly in the spirit of the rules - maximum of 9 different images per second.A lot of cameras taking the easy way out simply write 1 frame in 3 or 4 to the display so are as you say 8.33 or 7.5HzThe Argus ones write 1fieldin 6 or 7 to the display, so do give 9 different images per second and I feel that looks a lot better than the small difference says.

author: Bill W
author_rank: Super Contributor
timestamp: February 04, 2025, 01:17:03 am
content: Quote from: Topcode on February 03, 2025, 04:18:08 amThat is how I did the big lens camera - repurposed a FLIR-One.http://www.fire-tics.co.uk/project4/index.htmYou unclip the shutter, unscrew the FLIR lens, and put the shutter block back in its' place.

author: Bill W
author_rank: Super Contributor
timestamp: February 04, 2025, 01:40:18 am
content: Quote from: Topcode on February 02, 2025, 06:15:18 pmyes those were still image grabs from the attached phone.Quote from: Topcode on February 02, 2025, 06:15:18 pmThere is no thermal equivalent of 'black' as you are used to with visible light astro cameras, so no 'amp glow' either in most 8-14 bolometer systems. The biggest problem with altering the setup of a sensor via cooling is that you can easily head off out of the analogue dynamic range - as I had the opposite problem with cameras heating up to 85°C when in fires.You would not be dealing with just extreme fixed pattern noise either, each pixel has a different gain to the neighbours - about +/-25% is considered acceptable.Here is a typical real raw data frame and how it looks after subtracting a flat field - all done in ImageJ

author: Vipitis
author_rank: Frequent Contributor
timestamp: February 04, 2025, 04:03:58 pm
content: I still think this might be a good entryhttps://www.eevblog.com/forum/thermal-imaging/northpoint-akir-01/msg5793483/There is still some listed at 399€ on German eBay. mote that might will get a working camera. But not the datasheet or low level access to really modify that module. See the thread for about as far as it gets. recording frames with no compression and locked gain is probably your best shot at doing any observations. But the noise floor will be way to high to even get any signal.And integration time doesn't work like a cmos camera. Longer doesn't mean more signal. If you look at the night sky you get a really low value and that's about what you get even when staring at a planet, a satellite, a DSO. the moon shows up during daytime and nighttime and so does the sun.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: February 04, 2025, 04:36:44 pm
content: I would slightly disagree with one of Fraser's points on optics. For photon counting detectors the keys are the ratio of target/image photons to "background" photons and the ratio of target photons to electronic noise. Large optics and low f numbers help with the latter but create challenges for the first. The thermal background photons come from self emissions of the optics and from the support structures and mounts. For various reasons it is challenging to chill a terrestrial telescope enough to materially reduce these, but a cold shield, an optical mask in the detector dewar can effectively eliminate the contribution from structures and mounts. Such shields are far more effective and easier to fabricate for higher f number systems.

author: Topcode
author_rank: Newbie
timestamp: February 05, 2025, 01:33:31 am
content: Quote from: Vipitis on February 04, 2025, 04:03:58 pmI think you severely overestimate the level of signal untracked, or even just relatively short exposure astro gives you to work with. See this imgur albumhttps://imgur.com/a/lUuN5Or, it has a comparison between sky survey data, my final stack, and one subframe from the stack, zoomed into a dim, distant, galaxy group. One of the larger galaxies I have marked with a red arrow. It just maybe barely appears in the subframe, and many of the smaller galaxies near it don't. Just because you cant see it in a subframe, doesnt mean it isn't still there.Second, it should mean more signal off the sensor, even if radiometric calibration scales it to the same output temperature, at least it does with the low quality thermopile inside the MLX module I have(see attached), and if thermopiles turn out to be a superior technology for this, that would be the funniest thing I've ever seen. But based on my limited understanding of microbolometers, I do think that they would benefit from increased exposure time. And with how bad thermopiles are, even if that were the case, I think microbolometers would still come ontop, preventing us from the bliss of that reality.

author: Vipitis
author_rank: Frequent Contributor
timestamp: February 05, 2025, 10:57:58 am
content: I have seen and done some really impressive astro post processing. But it will be sorta difficult to even track and stack your images **with not stars in the signal** . Maybe if you have a guided mount for your scope this is less of an issue.I have lepton 2.5 and 3.5 based cameras, and remember doing like 200 subs of the night sky on a night with really good conditions... And nothing in the stack. not even mars. I can try to find the subs on my old hard drive and share them. You will need to extract the unscaled data using exiftool. But that is detailed somewhere in the forum too.

author: Bill W
author_rank: Super Contributor
timestamp: February 05, 2025, 10:59:50 am
content: Is that curve for the thermopile not simply showing the effect of averaging out of measurement noise ?eg in the ADC's ?A thermopile is a thermocouple - it has a voltage based on its' temperature and does not keep going up the longer you stare at something in the manner of a photon counting CCD, it reaches equilibrium.Same as a thermistor - and a bolometer is just a thermistor array.In a bolometer the sensor 'integration time' is a function in the measurement of the 'thermistor-pixel' resistance - how long you leave the 'thermistor-pixel' connected to the capacitor attached to the ADC

author: CatalinaWOW
author_rank: Super Contributor
timestamp: February 05, 2025, 03:06:48 pm
content: In a bolometer the "integration time" is the thermal time constant of the cell. As Bill W says integration time in the readout only helps with the measurement noise.

author: Bill W
author_rank: Super Contributor
timestamp: February 05, 2025, 04:26:52 pm
content: Quote from: CatalinaWOW on February 05, 2025, 03:06:48 pmI did also use integration time to deal with large dynamic ranges.The upper mode on an Argus4 is at half-integration as the earlier ULIS/LinRed sensors had less by way of explicit gain functions.Bill

author: Topcode
author_rank: Newbie
timestamp: February 05, 2025, 05:28:09 pm
content: Quote from: Vipitis on February 05, 2025, 10:57:58 amI do have a guided mount, at least now. Although I will have to figure out a way to transfer alignment data, it shouldn't be that hard. Once I stacked 17 thousand 1/5 second frames using a narrow band filter while untracked. Turned out pretty well, got a nice image of the ring nebula. Point is, stacking a few thousand images to get some signal is not anything I haven't done before.As for what Bill is saying, I dunno then, but I would think that thermal systems should still be subject to the same noise sources as other systems, which are conventionally eliminated by increased exposure, but if they cant be eliminated by increased exposure, well, that sucks.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: February 05, 2025, 11:59:20 pm
content: Quote from: Topcode on February 05, 2025, 05:28:09 pmJust to be clear, I think by thermal systems you mean bolometers. Photon counting detectors like InSb, HgCdTe and doped Silicon do well with increased exposure.Bolometers literally approach thermal equilibrium with their environment. That is there is a steady state temperature resulting from the radiation input of the scene, and the conduction and radiation losses from the detector element to its mounts and surroundings. If there is a step change in the scene (such as be moving a star onto the pixel) the bolometer element warms with a thermal time constant determined by it's mass, heat capacity, and thermal resistance to it's surroundings. The cells are usually designed with a time constant matching the intended frame rates. The ones I have personally seen are in the range of 10-30 milliseconds. In some sense this is the integration time of the bolometer, as it roughly defines the time when most of the temperature change takes place. The temperature change is evaluating using the change in resistance of the bolometer material. Typically vanadium oxide is used for the resistor since it has a "high" temperature coefficient of about 2% per degree C. As you can imagine the change in temperature from a stellar source is millidegrees at most so you are measuring resistance changes on the order of .002%. Measurement noise is the issue.In principal you can improve the images by frame stacking. The issue is that the initial SNR is very low compared to photon sensors, and some of the noises are not nice gaussian terms so they don't average out as well or rapidly.

author: Vipitis
author_rank: Frequent Contributor
timestamp: February 06, 2025, 10:52:31 am
content: Which is why the suggestion from Fraser is about a photon counting/QWIP detector. These are more comparable to CMOS/CCD cameras you are used to. But they are horribly expensive, require specialty software (with licenses), mostly LWIR and require cryocooling (sterling cooler/LN2).So maybe finding an eBay bargain there is your best bet.You probably need an optically impossible telescope to image DSOs with microbolometers.just give your thermal pile a try and see if anything but noise shows up when you look at M42.

author: Fraser
author_rank: Super Contributor
timestamp: February 06, 2025, 12:18:43 pm
content: This seems a good time to highlight this post from several years ago in case the OP begins searching for old cooled thermal cameras……https://www.eevblog.com/forum/thermal-imaging/thermal-camera-purchasing-the-perils-of-buying-a-cooled-camera/Fraser

author: artag
author_rank: Super Contributor
timestamp: February 06, 2025, 03:27:45 pm
content: What do you use for a lens system ? Do normal optical telescope lenses work at these wavelengths ?

author: Fraser
author_rank: Super Contributor
timestamp: February 06, 2025, 04:38:47 pm
content: artag,The usual approach is to use a reflector type telescope with mirrors that have a aluminium or gold coated reflective top surface (1st surface). Any glass in the optical path will prevent passage of the MWIR/LWIR thermal energy, just as with normal thermal imaging lenses. Whilst it is possible to make refractor thermal telescopes for astronomy, the cost of the lens elements is very high.Fraser

author: Topcode
author_rank: Newbie
timestamp: February 06, 2025, 05:14:45 pm
content: Quote from: Fraser on February 06, 2025, 04:38:47 pmyeah I have a pretty standard aluminum coating 5 inch newtonian, but I am also going to try to use a small germanium planoconvex lens as a reducer to increase the speed and make the fov a bit more reasonable.Quote from: Vipitis on February 06, 2025, 10:52:31 amI would but its already embedded in another project which I cant really take apart. and also also based onthis graphI found, they suck so much more than microbolometers. I also don't actually have my telescope with my right now.

author: Bill W
author_rank: Super Contributor
timestamp: February 06, 2025, 11:30:43 pm
content: Quote from: Topcode on February 05, 2025, 05:28:09 pmThe electronic noise is averaged out by multiple 'exposures' (ADC reads), normal temporal filtering and then there is the eye-brain time constant if dealing in video not stills.So on an Argus 4 or P/T/MiTIC (ULIS A-Si detectors) the sensor is read twice at 14 bit, averaged in the raw and then the processed 30Hz image gets a further 2x averaging and from the observers viewpoint there a ~3x averaging by the eye-brain system.The other options that can be deployed are around changing the sensor biases, which would be analogous to 'ISO film speed' in the optical world. That changes the nominal 8mV/°K (f/1 optics) response and reduces the effect of ADC quantisation (you only have 14 bits over a 4V span) as well as constant noise sources.Some noise of course increases with the biases, so it is not a one way win.That approach though needs access to factory level software and recalibration.For fire cameras of course I was more concerned with reducing the sensitivity to image 1000°CHowever all of this is for objects around 300°K which are good for emitting 8-14µm energy. Go under 250°K and there is very little energy coming off in-band so SNR takes a dive, swamped by energy from the lens system