Did someone know what happen with this drone camera?

[Dianyang]

Hi,

I sold some thermal cameras to my customers for his drone, and we've sold many thermal cameras with the same specifications to other customers, but today he said some cameras has some dirty like black ink painted on the image, cannot remove it even place to somewhere for a lone time.

From our experience, even see the sun will not cause this kind of damage, and also drone crash will damage the whole image.

We are confused with this problem because we sold and used a lot of thermal cameras before, never encounter this.

Is there anyone saw this kind of problem before?

Thanks!

[DuPe]

Laser pointer?

[Fraser]

This is classic damage due to abuse.

Note the ‘trail’ that is formed as the pixels are damaged. As has been stated, a Laser operating in the passband of the cameras optics is well known for causing such harm to pixels. People experiment with Lasers and wish to check the beam quality. They have been known to destroy thermal imaging cameras by directly exposing the sensor array to the laser beams energy without adequate attenuation to protect it from damage.

FLIR have detailed such sources of damage and look at the SC660 image with its Sun induced burn-in damage. The FLIR SC660 uses an A-Si sensor array rather than VOx and FLIR say it is vulnerable to sun damage. Look at the ‘tail’ tracing the course of illumination and damage. Look familiar ? I know you say your camera is not damaged by the sun but there are other energy sources that are ‘in-band’ that can cause such damage. Even a simple high powered Halogen lamp is a broad spectrum radiator capable of harming a sensor array if enough energy falls within the passband of the cameras optics.

https://flir.custhelp.com/app/answers/detail/a_id/3192/~/exposing-camera-detectors-to-high-energy-sources/session/L2F2LzEvdGltZS8xNTg0MzYyNDU2L2dlbi8xNTg0MzYyNDU2L3NpZC9mVWhEbW9zSiU3RUUzVVM2VmI3WVpEUUd0REJZOUp5d3RnZnNiamUzR2cwQTlobjlLUzRRd3lRZHNlemRQTDdRTWdWYzVjVXJzNkRqTkFUZUolN0VtZWdzQzJheWFjbHkySjdoNHo4M2d1MTI2dlBnTjMyJTdFY1drRWFXYnclMjElMjE=

So what is the damage caused you may ask ?

Well presenting an excessive level of energy to a pixel causes significant heating as one might expect. This excessive heating can cause a range of changes in the pixel. The possibilities are listed below:

1: Excess heat in the pixel and surrounding structures causes temporary defects in the image that decrease with time and are not permanent. Basically a ghost’ image that fades as the heat is dissipated from the sensors die.

2. Excess heat in the pixel causes permanent changes in the pixels thermal response but the pixel remains operational. This damage causes the pixel to appear hotter of colder than the rest of the pixels around it and is an abuse instigated non uniformity issue. Some cameras can correct fir this with the FFC function but more commonly, the camera will require a calibration that will create a new NUC and dead pixel table. The damages pixel(S) will be tested for response and either gain correction applied or marked as dead due to being outside the acceptable correction range.

3. Excess heat in the pixel actually burns its surface and renders it non functional due to warping of the pixel structure and potentially destruction of the supporting ‘legs’. The pixel is effectively dead. This dead pixel would need to be logged in the dead pixel table so that algorithms in the video processing stages can hide its presence, just like any dead pixel. Sadly life is rarely so simple as many pixels are often damaged and so dead pixel ‘clusters’ ASR’s formed. Such clusters would normally cause a sensor array to be rejected at the production stage. As such the dead pixel video processing is likely unable to cope with the cluster and either will fail to address it, or fail to hide it adequately. A full calibration is recommended in such cases anyway as there is a need to capture any and all effects if the damage on the sensor array. This ‘cluster’ type of damage is usually beyond rectification and requires a new sensor array to be fitted.

4. In extreme cases of excess energy, usually from a ‘in-band’ powerful laser, the energy melts the pixel causing collateral damage around it and can damage the die surface behind the pixel. Such damage is usually catastrophic and a large area of the sensor array ceases to operate. This damage cannot be addressed with new calibration tables and the sensor array is scrap. There can also be damage to the AR optical layers of the lens system if the laser is of a high enough power. This is extreme and foolish abuse of a thermal camera and may actually be an attack on the camera to deliberately kill it. Think military use

I hope this helps.

For information. The image you have provided shows user abuse and FLIR would reject any warranty claim made if it was one of their cameras sent for repair.

Fraser

[Fraser]

Comment from FLIR on damage thresholds for the TAU and Boson cores. They refuse to provide a damage threshold figure as there are many variables. They do provide useful comment however.

https://flir.custhelp.com/app/answers/detail/a_id/3132/related/1/session/L2F2LzIvdGltZS8xNTg0MzY0MjY5L2dlbi8xNTg0MzY0MjY5L3NpZC9mVWM1anBtY1BvajA4d19MZ29YaU9oNW9JeUhsV3FHNTFrb0tXRCU3RVVpQm1pQ2VjWjU1S29YTGZ4a084UVB3bzdtNHo0a0owTXR5Rld2U3RWeUl2VVlvVVhSeFlfRDZzeERKbXBBMlpiU1NRYjlqMUV4S3VaejNndyUyMSUyMQ%3D%3D

Fraser

[Fraser]

If you can get hold of the actual raw image file and post it here we may be able to analyse the damage pattern burnt into the pixels. The ‘tails’ that I see already tell me that the cause of the damage was a well collimated beam of energy or a very powerful spot source of energy at close range. Note how the tail darkens and widens along some parts of its tracks. That is indicative of a non linear sweep rate with variable dwell time on the pixels as the energy tracks across the sensor die. The largest areas of damage tend to sit at the ends of the talks where the mean has tracked and then stopped at a location longer, causing greater localised damage.

The tails are like a breadcrumb trail. They show us the track of energy across the sensor array. A straight track or one with good geometry like a curve would normally indicate a stable mounting of the camera or damage source and mechanically accurate tracking caused either by nature (the Sun’s arc) or a mechanical mounting that moves in a predictable fashion.

The tails in the image are very random and suffers very unstable mounting of the camera or the source of energy. A hand held camera or energy source are my thoughts on this.

Fraser

[Fraser]

In cases such as this there is also the option to send the image to the provider of the thermal imaging sensor or core. They will likely have seen all manner of damage done to their products over the years and may give you a definitive diagnosis as to the likely cause of the damage. I can guarantee that they will not say that it is a manufacturing defect or natural degradation of the sensor array 

Fraser

[johnelot]

i had a mark with trail like this after the sun was in the view for a few seconds - it did not go away at all even with switching on and off etc , then i found i could force it to calibrate (even though its shutterless ) by holding a button on the keypad for quite a few seconds - it was cured - the mark went away completely - i should have taken pics but i thought it was burnt for ever , its a chinese core with keypad so i dont know if this can be done with other ones

[Dianyang]

Thanks for your detail description on this kind of damage, today I discussed this with our engineers, they said before in the summer did some test, they use the camera to directly view the sun for a long time, it will cause some temporary burn trace in the image, but place it in some place for some minutes, then power on the thermal camera, the burn traces is vanished.

So we consider it may not coming from the sun. Our engineers said it may came from some high energy light, maybe laser or something else.

[Fraser]

The reason that the Sun is not as damaging to the sensor array as we might expect is due to the wavelengths of energy that actually reach the pixels. The passband filtering in the optical path created by the AR coatings limits the exposure to 7um to 14um or even less. This is not the area of the Suns output spectrum that contains the greatest energy. Once adequately filtered, a VOx microbolometer will normally survive sun exposure without permanent damage. The sensor die just heats up and causes temporary reduction in performance with a hot spot at the point of greatest heating. From what I have read and seen, Amorphous Silicon (A-Si) microbolometers are more fragile and vulnerable to damage from a high energy exposure that a VOx sensor would survive.

Fraser

[Fraser]

The attached Solar Spectrum plot shows where most energy is concentrated from the Sun at the earths surface.

As can be seen, the energy level drops off considerably as it approaches the MWIR band and the story is similar in the LWIR band that is not shown.

You can see why it is a bad idea to point a visible light camera at the sun though ! If the sensor does not get fried, the aperture iris will certainly get cooked. Large amounts of attenuation are needed for Sun photography in the visible light spectrum.

Fraser

[Emo]

Hi,

Could it be that the drones were used in an environment with active Lidars or even lidar drones. Multiple example video's circulate the internet of camera's being damaged by accidentally being in the direct bundle of these scanners

Eric

[Ultrapurple]

If the camera was on a drone then I would guess it was (mostly) pointing down or horizontal. On the face of it, that sounds like it might rule out Sun damage, but doesn't take into account the possibility of reflections, e.g. from (calm) water.

That said, I concur with the previous comments that it's relatively hard to cause serious, permanent damage to the sensor by looking relatively briefly at the Sun. But other very powerful LWIR sources abound. I managed to image a fierce barbecue with a FLIR SC-660, without damage, however that specific camera is designed to look at up to 2000°C. Even so, the 700°C of the BBQ coals was a challenge, and the sensor required frequent NUC events to calibrate out the temporary 'burn-in'. Moving the camera quickly from the hot coals to another scene showed an after-image of the BBQ until the next NUC.

I'm afraid the level of burn-in on the sensor you show may well mean it is scrap. However, if you could point it at something uniformly VERY hot (say 250°C, just in range of a domestic oven) you might be able to see whether the damaged pixels have any response at all. If there is some sensitivity then it's remotely possible the sensor might be salvageable. Otherwise, it's something to put on the shelf to demonstrate to future clients why they really, REALLY shouldn't point a thermal camera at an excessively hot & powerful point source.

[Uho]

I once attempted to remove broken pixels. If damaged by a laser, there are a lot of them. Single I could remove. Thick lines no. Damage in your case is very similar to a laser.

[Fraser]

You have to wonder what is going through someone’s mind when they decide to place an expensive thermal cameras input “on-axis” with a powerful laser beam, most likely CO2 10.6um 

I can only think that some laser users have heard of laser beam profiling using SWIR, MWIR and LWIR cameras but do not understand the process and precautions needed for such tests. They probably think that a LWIR camera covers the 10.6um wavelength and is ‘sun safe’ so OK to illuminate with a laser.

That can be a gut wrenching mistake when you effectively fry your expensive thermal camera FPA

FLIR carry out fixed price repairs on most of their cameras but they do not include microbolometer damage that is not due to a manufacturing fault. Microbolometer manufacturing  faults are covered for 10 years and this covers non abuse related failure as well. Replacing a microbolometer outside of warranty is often only financially viable on a high end, very expensive, camera.

Fraser.

[johnelot]

it does look exactly the same as i had when i pointed my thermal at the sun - it would not go away with use and every time i turned it back on it was still there = it is shutterless amorphous silicon type -cant help thinking  if you could force it to calibrate its self somehow it could just fix it , where mine was burnt black it is now just as normal and the pixels work fine where it was a black mark

[ivaylo]

Very interesting thread. If the sun is such a concern this begs the question how does Flir design their IR security cameras. The FC series manual contains this “Once installed, the camera may point directly east or west, and this may cause the sun to be in the field of view during certain portions of the day. We do not recommend intentionally viewing the sun, but looking at the sun will not permanently damage the sensor. In fact the thermal imaging camera often provides a considerable advantage over a conventional camera in this type of back-lit situation.” And from what I can tell they contain just a Tau 2 inside - https://www.eevblog.com/forum/thermal-imaging/is-this-a-tau-2-core-(and-a-few-more-questions)/

[Bud]

In Fraser's image it is interesting that only one airplane left a thermal tail behind it, could that indicate some sort of engine problem 

[bap2703]

The attached Solar Spectrum plot shows where most energy is concentrated from the Sun at the earths surface.

As can be seen, the energy level drops off considerably as it approaches the MWIR band and the story is similar in the LWIR band that is not shown.

You can see why it is a bad idea to point a visible light camera at the sun though ! If the sensor does not get fried, the aperture iris will certainly get cooked. Large amounts of attenuation are needed for Sun photography in the visible light spectrum.

Fraser

Power dropping in the LWIR band compared to in the visible band doesn't mean it is low... it's just lower

What I see from Dianyang's pictures is that the pattern isn't the same on both.
Either you are showing us two damaged devices or the damaging process can be recovered, like usual sun exposure.

[Fraser]

To quote Dianyang........

“ I sold some thermal cameras to my customers for his drone, and we've sold many thermal cameras with the same specifications to other customers, but today he said some cameras has some dirty like black ink painted on the image, cannot remove it even place to somewhere for a lone time.”

 

From this we can surmise that the two pictures are from different cameras.

Fraser