EEVblog Electronics Community Forum

Products => Thermal Imaging => Topic started by: globoy on March 11, 2021, 06:35:17 pm

Title: Lepton 3.5 output drifting all over the place
Post by: globoy on March 11, 2021, 06:35:17 pm

I have a Lepton 3.5 that is acting very strangely.  It works in that it appears to be generating pixel data that is properly in relation to other pixel data (a linear scaled image looks fine) however its radiometric output is drifting all over the place.  For example if it is looking at a scene that has about a 40°C range then the min and max values are always 40°C apart but drift all over the place.  The drift rate is roughly one degree every few seconds.  Usually the range seems to be 20-30°C below what it should be but I've seen it drift all the way down to 0K on occasion.

I don't suspect the camera itself as the particular Lepton behaves the same way in different cameras and other Leptons work fine in the same camera.

Any idea of what might be going on?  Maybe its internal temperature sensor has failed?

Title: Re: Lepton 3.5 output drifting all over the place
Post by: Fraser on March 11, 2021, 07:00:59 pm

Check the quality of the connections between the front mounted thermistor and the Lepton electronics package.

Poor connections have been seen in the past.

Fraser

Images are of a Lepton 2.5 from this URL:

https://www.richis-lab.de/Opto04.htm (https://www.richis-lab.de/Opto04.htm)

Title: Re: Lepton 3.5 output drifting all over the place
Post by: globoy on March 12, 2021, 03:01:56 am

Thanks for that.  I think that was it.  Not the connection to the thermistor but to the base substrate.  I used a pin to mush the gold(?) material against the trace on the side of the camera.  Not so great photos below.

Also I saw the damage that repeatedly plugging and unplugging the module does to its contacts.  They are also made of ultra soft material that is simply wiped off.

Title: Re: Lepton 3.5 output drifting all over the place
Post by: Fraser on March 12, 2021, 06:30:43 am

I am pleased that this was a resolvable situation for you. If the goes fails I suppose that conductive silver loaded paint could be used to bridge any gaps or recreate contacts. In the good old days that spa silver lauded paint was effective in repairing car rear window delisted elements so it is tough stuff. Expensive but effective. Beware of some cheaper products that are not as conductive. I still have the 5ml bottle of this ‘paint’ from 35 years ago and it is still useable !

https://uk.rs-online.com/web/p/adhesives/1239911/?cm_mmc=UK-PLA-DS3A-_-google-_-PLA_UK_EN_Adhesives_%26_Sealants_%26_Tapes_Whoop-_-Adhesives_Whoop-_-1239911&matchtype=&pla-337597424091&gclid=Cj0KCQiAnKeCBhDPARIsAFDTLTL4Uzegr5UhUeOSsOrI_rbJX02NgcKntEHn-dSPK_chdkTjEeT4YD8aAqNxEALw_wcB&gclsrc=aw.ds

Fraser