The evaluation of a pyroelectric detector with and without a sprayed multi-walled carbon nanotube coating

The radiometric properties of a pyroelectric detector based on a LiTaO3 crystal were studied when the detector had a sprayed multi-walled carbon nanotube (MWCNT) coating and when the coating was removed. The spatial uniformity of response of the bare detector improved as the modulation frequency increased in the 4–70 Hz range whereas the spatial uniformity of response of the coated detector deteriorated as the modulation frequency increased over the same range. The uncoated detector was observed to have a “super-linear” response whereas the linearity of response of the coated detector was shown to be “sub-linear”. The origin and implications of this behaviour are discussed.

► A pyroelectric detector was evaluated without and with a sprayed MWCNT black coating.
► Its spectral responsivity varies by 5% in the 0.9–24 μm wavelength range.
► The MWCNT coating is the source of the spatial non-uniformities in its response.
► The MWCNT coating plays a major role in the linearity characteristics of the detector.
► Reasons for this behaviour are proposed.