hi Michal

Most black pigments are based on carbon: graphite pencil, indian ink, bone black, ivory black, vine black, and lamp black are all essentially carbon and should absorb well in the visible and near infra red. I'm not sure what they do in the SWIR though.

One possibility would be to find a material that you know absorbs well in the SWIR and use it as a support or  as an undercoat on which to apply your coat of carbon black.  By using one absorber on top of the other, in separate coats, you should be able to make a optically subtractive mixture that works in both regions, as long as one does not fluoresce. 

If you cannot find it as a pigment you can grind it up with some medium to form a crude paint.

Hope you are well and thriving,

regards

Stephen

the question is not simple, I asked also to some colleagues. This is the result:

- You may put a sheet of heavy black cloth. Because there are not "reference" clothes, you should first test it with the scanner.

- you could use a black paints as those used for optical instruments on satellites but i do not know trade names. Also in this case, preliminary tests are necessary.

good luck

perla

I use a black plastic material that absorbes quite well, whereas I use it for little objects (small field of view needed).

Black sandpaper works quite well in the range 900-1700 nm.

Regards,

Cecilia