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The future of cooled MWIR cameras?

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cejoba:
Hi, I'm just thinking.
With most devices goes to "solid state", what will happen to the cooled MWIR cameras, with heavy, expensive, short-life cooler?
Will they continue to develop because of the advantages, or don't need cooler in the future, or be replaced by uncooled ones?
Anyone want to talk about this?

ArsenioDev:
Thing with MWIR is the requirement for cooling is a quantum well limitation of the MCT/InSb sensor materials, note response graphs of cooled vs uncooled material on this responsivity graph.
You'd have to discover some wacky magic material to get true uncooled and then evolve ROIC and process over several gens to get high fidelity and linearity across an array. [attachimg=1]

Fraser:
 Cejoba,

Cooled MWIR and Uncooled LWIR both have their advantages and disadvantages. Traditionally a cooled MWIR or LWIR FPA has been used for the best quality low noise imagery with excellent NeTD figures. In science and Military applications the cooled technologies are still very much alive and kicking. Cooled cameras high sensitivity permits higher F number lenses and so smaller lenses for long distance work. There is, of course, the need for a MWIR capability and this currently sits in the cooled FPA realm.

With regard to cooler life, the technology has improved greatly and the old 2000 hour life of a Stirling Coller has extended to 10,000+ hours for a rotary cooler and 100,000+ Hours for linear coolers. Cooler lifespan is not the issue that it once was and the benefits of the cooled camera can outweigh the inconvenience of cool-down times, power consumption, bulk and service life.

You will note that we do not see cooled thermal cameras in the consumer marketplace. There is good reason for this. Cooled cameras are very expensive compared to uncooled microbolometer types. The consumer market is well served by the uncooled technology and there is little appetite amongst manufacturers to try to market expensive cooled solutions against inexpensive uncooled models. The cooled cameras remain the preserve of the “Professional” users, where they provide excellent, if expensive thermal imaging. If you need low noise MWIR imaging, you have little choice but to buy an expensive cooled camera. LWIR serves most needs in the consumer/Prosumer market though. It is in Science and the Military that MWIR has its main customer base.

I have noted ever improving NeTD figures stated for uncooled Microbolometers and this has interested me. It is not uncommon to see an NeTD of 35mK stated for a modern microbolometer.  It is clear that microbolometer noise management has been an area of significant development over the years. I still think cooled cameras will produce a better low noise image however.

So, will we see the expensive, bulky and finite service life Stirling Cooled MWIR cameras disappear and go the way of BST and PZT FPA based technologies ? Nope, there is no better choice of technology for more demanding science and military applications. That said, they are already scarce outside Science Labs, Industry and the Military and that will likely remain the case. Used units can be amazing…… if they still work ! I wrote a piece on buying used cooled cameras some time ago. I will add a link in a minute.

I own a few cooled MWIR cameras that are still happily working and producing lovely imagery. I love that technology and it was in the mid 1990’s with an AGEMA THV550 handheld cooled thermal camera that I discovered how great a cooled FPA camera can be. A few years back I won an auction for a very nice THV550 with an end price of 99 pence ! I was amazed when I received the camera and found it to be in perfect working order. Sometimes it is better to be born lucky than rich  ;D

https://www.eevblog.com/forum/thermal-imaging/a-stirling-cooled-qvga-thermal-camera-for-99-pence-!-yep-no-kidding/

Fraser

Fraser:
The link to my post discussing the purchase of used cooled cameras…..

https://www.eevblog.com/forum/thermal-imaging/thermal-camera-purchasing-the-perils-of-buying-a-cooled-camera/

Fraser

Fraser:
While we are discussing cooled cameras, let us not forget that the market for Stirling coolers is still very healthy. Such coolers are to be found in low noise RF amplification systems and the toys that NASA likes sending into space on voyages of discovery ! Cooled semiconductors are still required in specialist applications. The coolers were never exactly a cheap item on the BoM and that has not changed…. They have just been developed to have a longer, more reliable life  :-+ I wonder if Voyager 1 and 2 contained Stirling Collers and if so, are they still working ?

https://eng.ox.ac.uk/cryogenics/research/cryocoolers-for-space-applications/

Fraser

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