Hi. Many surveillance and phone and other cameras can be made to see infrared by removing their IR blocking filter in the lens.

Is sensitivity to thermal included when the filter is removed; or the sensor works only to a near-IR and thermal sensing is not 'near' ? What is a thermal camera spectrum ? ~12um ? Is any common canibalizable camera sensor that can be used for 'toy grade' thermal imaging ?

If you want, jump to time stamp 1:10 at --> https://www.youtube.com/watch?v=2YEvkOVCaNI

9 minutes ago, Externet said:

Hi. Many surveillance and phone and other cameras can be made to see infrared by removing their IR blocking filter in the lens.

Is sensitivity to thermal included when the filter is removed; or the sensor works only to a near-IR and thermal sensing is not 'near' ? What is a thermal camera spectrum ? ~12um ? Is any common canibalizable camera sensor that can be used for 'toy grade' thermal imaging ?

If you want, jump to time stamp 1:10 at --> https://www.youtube.com/watch?v=2YEvkOVCaNI

Generally speaking, the filter is not on the lens, but in front of the sensor. Modern CMOS (or CCD) sensors are able to capture IR light. But the capacity is directly dependent on the precise sensor and can vary a lot. Also, if you still want to take images, you still need an (IR permissive) filter, otherwise it tends to be a blurry mess. I just happen to have a brochure where you can see examples of the spectral response of some sensors and the impact of filters (not an endorsement of that company).

https://www.hamamatsu.com/content/dam/hamamatsu-photonics/sites/documents/99_SALES_LIBRARY/ssd/image_sensor_kmpd0002e.pdf

2 hours ago, Externet said:

Is sensitivity to thermal included when the filter is removed; or the sensor works only to a near-IR and thermal sensing is not 'near' ?

For most cameras, it’s the latter. Silicon sensors only work out to 1.1 microns, other common ones not much further, and thermal is out in the 10-15 micron range. Thermal imaging uses different technology.

In the lab I worked in, we used cheap black-and-white surveillance systems, since they had no filter to begin with. A rate example of the cheaper commercial option being the right tool, rather than boutique lab stuff.

I once modified a webcam by removing the IR filter to take pictures in the lab. It had to be manual focus, because autofocus is calibrated with the filter in place