Author Topic: What's Wrong with my Thermal imager  (Read 752 times)

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Offline falcom

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What's Wrong with my Thermal imager
« on: April 23, 2018, 06:49:24 am »
I have this non working prototype Insight thermal scope. All i know is that it has a 320x240 sensor.
I have posted a video of the video output. I don't know where to start.
Is it the sensor?
The Processor?
The Video Section?



 

Offline railrun

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Re: What's Wrong with my Thermal imager
« Reply #1 on: April 23, 2018, 07:06:27 am »
Shutter still closed?
 

Online Fraser

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Re: What's Wrong with my Thermal imager
« Reply #2 on: April 23, 2018, 07:21:23 am »
We need more information about the camera. Pictures may help.

Is it cooled or uncooled, BST or microbolometer? These important pieces of information help to determine what parts in the camera may not be working properly. Pictures of the interior of the camera will tell me a lot.

Noise on the produced image and a lack of warning messages is a good sign. As has been stated, the issue can be as simple as a stuck FFC flag or a failed chopper wheel motor (if BST sensor based).

If the lens can be removed, please provide a picture of what us seen when looking towards the sensor.

On the very little information that can be gathered from the video, I believe the thermal sensor array and image processing electronics are working. Something is preventing the thermal imaging array producing a thermal image at its output however.

Fraser
« Last Edit: April 23, 2018, 07:46:07 am by Fraser »
 

Offline falcom

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Re: What's Wrong with my Thermal imager
« Reply #3 on: April 23, 2018, 10:55:49 am »
I have attached some pictures. From what I guess and similar cameras I have seen it is similar to the DRS U3510 uncooled microbolometer.

 No wiring for shutter that I can see.


 

Online Fraser

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Re: What's Wrong with my Thermal imager
« Reply #4 on: April 25, 2018, 02:43:06 am »
Hi,

Thanks for the pictures. It appears to be a standard microbolometer core but it could be running in a flagless FFC mode due to its application as a weapon thermal sight.

Are you able to remove the lens to gain a view of the microbolometer to ensure the optical path is open ?

Please also confirm where you are located in the world.

Fraser
 

Offline falcom

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Re: What's Wrong with my Thermal imager
« Reply #5 on: April 25, 2018, 05:54:08 am »
I am in The USA.
Here is a picture of the FPA after removing a ton of epoxy.
 

Offline james_s

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Re: What's Wrong with my Thermal imager
« Reply #6 on: April 25, 2018, 09:27:15 am »
Did it ever work? You mention it's a prototype, perhaps the firmware on it is unfinished or broken? I've worked with embedded products where unlocked firmware builds had built in time bombs that are good for x number of boots/days before a new build has to be loaded.
 

Online Fraser

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Re: What's Wrong with my Thermal imager
« Reply #7 on: April 25, 2018, 10:50:32 pm »
This is a bit of a mystery to me. When approaching a faulty thermal camera there are some very basic observations to be made. I list them below with your situation next to them......

1. Any response to power on command or button ? YES
2. Does camera display light ? YES
3. Does camera boot ? YES
4. Are any menus available and do they work ? YES and YES
5. Is a thermal scene displayed ? NO
6. If NO, is there row and column noise visible on the display ? YES
7. Does the FFC function work ? It appears to function (CAL)
8. Is the noise on the display random or fixed ? Random

The above simple functionality check would indicate to me the following.....

The camera is completing its boot sequence and not crashing afterwards. The video processing and display electronics are operating correctly.

So what could prevent a thermal image being formed ? Some possibilities follow ........

1. Microbolometer is blinded by something in the optical path
2. The microbolometer is working but it's blind and active pixel bias voltages are incorrect.
3. The microbolometer vacuum has leaked and the die is now 'up to atmosphere' destroying its thermal sensitivity.
4. The interface between the microbolometer and video processing circuits has failed so we are just seeing amplifier and ADC noise and not microbolometer row and column noise ? Seems unlikely but still a possibility.
We are definitely seeing individual columns in your video though.

Without having the unit on the bench in front of me, it is very hard to comment further. I would be probing the microbolometer pins to identify them and then checking the various bias, supply and signalling lines that should be present.
The microbolometer produces an analogue output so you should see a change in that output pin on an oscilloscope of a hot object passes across the microbolometer window (no lens fitted) but do not touch the window ! A soldering iron at a few centimetres distance usually works.

I regret remote repair of a thermal camera is not easy and I have promised myself not to undertake such again as it is just too time cinsuming for me. I am in the UK so sadly direct inspection of the 'patient' is not possible.

Fraser
« Last Edit: April 28, 2018, 12:22:26 am by Fraser »
 


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