How to fix Boson sensor surface scratches?

[hap2001]

Hi, one of my Boson core have scratches on the sensor surface, which also show on final pictures, I wonder if I can polish it somehow to get it smooth again? Thanks.

[Fraser]

Sadly NO !

I assume that you are talking about the actual microbolometer window, rather than any protective window that has been mounted in front of the microbolometer ? The microbolometer window is made from an IR transmissive material that can be thin silicon, Germanium or an IR transmissive Chalcogenide glass. The window has an anti-reflective coating applied to it, similar to that found on the associated lens system. Sadly the AR coating on the window is very fragile and easily damaged. It is possible to clean the a window with suitable tools and fluids but a scratch is permanent and any effort to “buff it out” will destroy the AR coating and still not remove the scratch that is in the window material. Remember, the only way to remove a scratch is to lower the height of the material around it to the depth of the scratch trough. Not possible on microbolometers without specialist kit and the ability to apply a new AR coating. A fresh calibration of the core can sometimes reduce the effect of a defect in the windows surface but, as the defect sits a distance from the actual pixels, there can still be optical anomalies when a lens is fitted due to beam angles etc.

Fraser

[Fraser]

Another warning…. Be aware that even gently cleaning a microbolometer window can present very real damage risks if the microbolometer has exposed bond wires. One slip or stray strand of cotton wool swab can spell disaster for the bond wires. I bought specialist CCD cleaning swabs that are single use and made from a special foam that does not scratch or disintegrate during use. They come in various sizes. I have some that are he size of a cocktail stick with a tiny sponge on the tip.

Fraser

[hap2001]

Thank you very much, yes I mean the ubolo surface, Boson have a even smaller package than TAU, Boson do not have a whole bunker around the naked ubolo, and there's no additional protective window in front of it.

However there is a metal frame that protects the bond wires, that's why I didn't damage all my Bosons on previous cleaning .

[Bill W]

For a fixed lens setup these should calibrate out, if you can do a full (gain+offset) recalibration.

That does not work if you change the lenses though, as the 'shadow' of the scratches would then fall on different pixels.

Bill