Author Topic: This company has figured out how to make cheaper SWIR cameras  (Read 1312 times)

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Offline Hyper_Spectral

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Re: This company has figured out how to make cheaper SWIR cameras
« Reply #25 on: April 11, 2019, 10:26:13 pm »
Psi,

I respect your viewpoint but I strongly suggest you do not test your theory in the real world. You will very likely get a very unpleasant surprise  ;) I will say no more but I do have inside knowledge. Respect ITAR and Wassenaar and you will be fine.

People talk about ITAR but do not forget the Wassenaar arrangement !

https://www.wassenaar.org/

Fraser

Interesting, for some reason Israel is not on the list.
 

Offline frogg

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Re: This company has figured out how to make cheaper SWIR cameras
« Reply #26 on: April 11, 2019, 10:46:34 pm »
I think I get your interest in SWIR more clearly now. It's more of a "We need capability to image in every possible wavelength" point of view.

Just the simple idea that an object appears differently when viewing different spectra is good enough to warrant interest :)
 

Offline CatalinaWOW

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Re: This company has figured out how to make cheaper SWIR cameras
« Reply #27 on: April 11, 2019, 10:59:11 pm »
There are a myriad of reasons for selecting spectral bands.  Availability of lens and window materials that are compatible with the operating environment.  The size aperture required for diffraction limited performance.  The need for additional systems such a cooling or thermal stabilization.  Atmospheric transmission, which may favor absorbtion, or uniformity over time, or lack of absorbtion.  The list goes on and on.

In any field, from smart phones, to radios to military gear there is advantage to be gained by clever use of technical capabilities.  The winners are those that go where others haven't and find useful capabilities.
 

Offline PedroDaGr8

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Re: This company has figured out how to make cheaper SWIR cameras
« Reply #28 on: April 12, 2019, 05:26:30 am »
Has anyone found patent applications or publications from this company which explain further details?

I am curious how the quantum dots actually work -- do they convert incoming light into visible-range photons or directly into electrons? How close is the CMOS architecture to a typical CMOS camera sensor? (Or is it indeed a standard camera chip, with just the quantum dot conversion layer added?)

The quantum efficiency and the noise level of their current products are somewhat disappointing. Regarding noise, I am surprised by the very high readout (?) noise baseline, which is there even at minimal exposure times. Yes, their chips are optimized for fast readout and are apparently uncooled, but why is the noise level that high?

I strongly doubt they are doing IR to visible light conversion, as that is stunningly inefficient. They would need a charge transfer/emissive layer which could absorb the excitons and allow for double exciton recombination (to provide the needed energies to go upwards in energy). This has been done using materials like ruberene and PbS quantum dots, but the QY was essentially 1.2%!

More likely, they are doing a direct charge transfer from the quantum dots to some sort of silicon substrate (maybe CMOS). In this motif, it would function as an array of tiny IR solar cells, providing an effective quantum yield up to the 20% range (not far off from the stated numbers here). As for the noise levels, heat is going to play a big role in the noise levels, as will design and structure. If they are transmitting the energy directly, this can induce more noise. Additionally, things like exciton relaxation time (i.e. does it recombine and emit light to adjacent pixels), isolation between the wells, etc.

Found this paper and it goes pretty deeply into the various types of quantum IR detectors: https://spie.org/samples/PM280.pdf
« Last Edit: April 12, 2019, 05:35:20 am by PedroDaGr8 »
The very existence of flamethrowers proves that some time, somewhere, someone said to themselves, "You know, I want to set those people over there on fire, but I'm just not close enough to get the job done." -George Carlin
 
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Offline CatalinaWOW

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Offline Fraser

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Re: This company has figured out how to make cheaper SWIR cameras
« Reply #30 on: April 12, 2019, 06:53:56 pm »
Paywalls are so annoying ..... thank goodness for Sci-Hub 😄
 

Offline Max Planck

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Re: This company has figured out how to make cheaper SWIR cameras
« Reply #31 on: April 13, 2019, 12:27:09 am »
Based on what was published so far, the company is using a standard, thin-film technology (thus lower costs), depositing PbS photodiodes directly on standard CMOS ROICs.

Max
 

Offline ebastler

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Re: This company has figured out how to make cheaper SWIR cameras
« Reply #32 on: April 13, 2019, 12:36:14 am »
Based on what was published so far, the company is using a standard, thin-film technology (thus lower costs), depositing PbS photodiodes directly on standard CMOS ROICs.

Max

Where did you find that information? I did not see anything about that on their website.
Thanks!
 


Online Marco

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Re: This company has figured out how to make cheaper SWIR cameras
« Reply #34 on: April 13, 2019, 01:00:34 am »
I strongly doubt they are doing IR to visible light conversion, as that is stunningly inefficient.

I recently saw a paper claiming a breakthrough with an in cavity non-linear crystal, 20% QE for MWIR to 800 nm ... not visible, but close enough.
 

Offline ebastler

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Re: This company has figured out how to make cheaper SWIR cameras
« Reply #35 on: April 13, 2019, 01:09:52 am »
Thank you!

So the fill factor, and hence the quantum efficiency, won't be getting great any time soon... But it is reassuring that these cameras are based on entirely standard CMOS sensors. So they could follow up with a TEC-cooled, slower readout, lower noise version pretty easily.
 

Offline CatalinaWOW

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Re: This company has figured out how to make cheaper SWIR cameras
« Reply #36 on: April 13, 2019, 03:57:41 am »
All of this has potential, but until someone makes a bunch it is dream stuff.  HgCdTe was going to solve all detector problems until the reality of producing large arrays with acceptable defect rates and at acceptable costs crept in.  Same for several other technologies.  It isn't necessarily that the technology is bad either.  It is partly that we have been spoiled by the hundreds of billions of dollars spent on silicon fabrication technology and often blissfully unaware of the many, many problems that have been solved along the road.  And only a portion of those solutions apply to these detectors.  They will never have enough production volume to warrant the investment that has solved so many problems in silicon.
 

Offline PedroDaGr8

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Re: This company has figured out how to make cheaper SWIR cameras
« Reply #37 on: April 16, 2019, 05:59:12 am »
I strongly doubt they are doing IR to visible light conversion, as that is stunningly inefficient.

I recently saw a paper claiming a breakthrough with an in cavity non-linear crystal, 20% QE for MWIR to 800 nm ... not visible, but close enough.

That structure is outside my realm of expertise as a former nanomaterials chemist. I was strictly speaking about Quantum Dot based non-linear conversion, which is asofar highly difficult and inefficient.

All of this has potential, but until someone makes a bunch it is dream stuff.  HgCdTe was going to solve all detector problems until the reality of producing large arrays with acceptable defect rates and at acceptable costs crept in.  Same for several other technologies.  It isn't necessarily that the technology is bad either.  It is partly that we have been spoiled by the hundreds of billions of dollars spent on silicon fabrication technology and often blissfully unaware of the many, many problems that have been solved along the road.  And only a portion of those solutions apply to these detectors.  They will never have enough production volume to warrant the investment that has solved so many problems in silicon.

That is ONE area where colloidal quantum dots excel, they can utilize a number of technologies currently employed in OLED manufacture (spin coat, die stamping, etc.) for manufacturing large arrays. That being said, as I mentioned earlier, they introduce their own suite of issues (the largest being how to get the charge out of the quantum dot, when most are designed to contain it in the center).
« Last Edit: April 16, 2019, 06:03:38 am by PedroDaGr8 »
The very existence of flamethrowers proves that some time, somewhere, someone said to themselves, "You know, I want to set those people over there on fire, but I'm just not close enough to get the job done." -George Carlin
 


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