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Posted: 1/31/2016 10:42:16 AM EDT
[Last Edit: 2/1/2016 7:23:54 AM EDT by SMC527]
Just as the title states...with the exception of being able to use a smaller sizes germanium lens for a given magnification and greater resolution (that's pretty straightforward)

What are the other advantages and disadvantages of smaller sized pixels in a microbolometer?

I read about Noise Equivalent Temperature Differential...and think I have a very rudimentary grasp of what it is, but could use further explanation if one of the intelligent folks on this board would like to assist.

Thanks in advance.
Link Posted: 2/1/2016 12:27:42 PM EDT
You ask a great question and there is a lot of debate going behind the scenes.

A focal plane with 25um pixels will have 4 times the area of a 12um so you would think 4 times the performance but yet the new 12um systems seem to be the best image, this does not make sense.

The best way to explain without going into Too much detail is that newer technology, process, fabrication and materials yields better sensitivity and combined with newer techniques with coding and algorithms yields better post processing.

The goal is in our space SWAP, size weight and power so smaller is better. If you made a 38um focal plane today it would completely outperform the 12um but we are not and what you compare sometimes is 10 year difference in technology.

So for now smaller is better, cannot believe I said that.
Link Posted: 2/1/2016 3:52:01 PM EDT
[Last Edit: 2/1/2016 3:52:58 PM EDT by SMC527]
Feel free to go into as much detail as needed.  I inquired so I could advance my knowledge.

Could you explain NETD further?

Posted Via AR15.Com Mobile
Link Posted: 2/2/2016 12:45:48 PM EDT
Also, what's SWAP?
Link Posted: 2/2/2016 1:15:59 PM EDT
Size, weight and power.

Reduce any one and your product becomes better. Many times through improved technology over time the gains can be had without increasing production cost and even sometimes lowering cost. Everyone wins.
Link Posted: 2/2/2016 7:18:39 PM EDT


One of the other main reasons for desiring a smaller pixel size, even if increased resolution is not the objective, is that the lenses used can be smaller, without any loss of performance.




MWIR and LWIR lenses are very expensive, so being able to reduce the lens size and material volume has a direct impact on size and weight, and especially cost. SWaP is important, but cost is the hidden factor no one mentions.




With a smaller pixel size, a proportionally smaller lens size is required, at the same lens speed, to achieve the same image and FOV.




Regards

David
Link Posted: 2/5/2016 8:47:11 AM EDT
bumping for further education....
Link Posted: 2/5/2016 9:20:17 AM EDT
What about pixel pitch/spacing?



I assume 17uM means each pixel sensor is 17uM wide, but is the gap between pixels a spec that we care about etc?






Link Posted: 2/6/2016 4:37:26 AM EDT
[Last Edit: 2/6/2016 4:37:57 AM EDT by cj7hawk]


Discussion ForumsJump to Quoted PostQuote History
Originally Posted By BushmanLA:



What about pixel pitch/spacing?





I assume 17uM means each pixel sensor is 17uM wide, but is the gap between pixels a spec that we care about etc?
View Quote





 
We don't have any control over it, though I expect it affects the ability to detect angularly small items... So in effect it's just an overall part of the quality of the FPA.







For the most part, we only care about the actual pitch itself.







Regards


David


 



p.s. For a parallel, look into CMOS cameras and back-lit CMOS cameras.
Link Posted: 2/6/2016 9:57:18 PM EDT
There is a point of no return when you have pixel sizes smaller than the IR wavelength emissions you are detecting.
Link Posted: 2/6/2016 10:31:37 PM EDT

Discussion ForumsJump to Quoted PostQuote History
Originally Posted By SkyPup:


There is a point of no return when you have pixel sizes smaller than the IR wavelength emissions you are detecting.
View Quote




 



We are kind of there at this point.  Thermal wavelength is 8-15uM and we are seeing 12uM pitch sensors I'm not sure at what point it starts meaning a performance hit though.
Link Posted: 2/25/2016 7:44:05 AM EDT
Bumping for further information and discussion.  I know there are some very intelligent individuals on this forum who can explain this in greater depth.
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