Gold-black coatings for freestanding pyroelectric detectors

Abstract

We describe the process of depositing gold-black on thin, freestanding pyroelectric detector substrates and compare this with previous work documented in the literature. We have evaluated gold-black coatings on thin, freestanding pyroelectric detector substrates by means of scanning electron microscope, Fourier transform infrared spectrophotometer reflectance, and spectral responsivity measurements. Spectrophotometric measurements indicate that reflectance at normal incidence varies by less than 1% at wavelengths shorter than 2.5 µm and by less than 10% at 10 µm. These results are correlated with the spectral responsivity of the detector and demonstrate that radiation not reflected by the gold-black is absorbed by the detector element. We have evaluated gold-black coatings as a function of position at two wavelengths and found variations of less than 1% at 1.25 µm and less than 5% at 10.3 µm, which demonstrates that spatial uniformity can be coating dependent. Gold-black coatings exposed to a 193 nm wavelength excimer laser were evaluated by visual inspection for damage and determined to have a damage threshold of approximately 38 mJ cm −2 .

Metamaterial Electromagnetic Wave Absorbers

“…[ 157 ] These devices fi nd good use in the IR wavelengths range and are particularly useful at THz frequencies. Traditional absorptive devices that have been used in microbolometers and pyroelectric detectors include metal black coatings, [ 158 ] carbon nanotubes, [ 159 ] and anti-resonant cavities (the most widely used). [ 160 , 161 ] Additionally, various components have been integrated into the composition of microbolometers in order to add elements of spectral sensitivity.…”

Photoacoustic ultrasound sources from diffusion-limited aggregates

“…In films prepared using this procedure, a complex granular structure results from the randomization of atomic velocities before aggregation in the gas phase [8][9][10][11][12] . Such films often but not always resemble the product of diffusion-limited aggregation.…”

Spectral selectivity in infrared thermal detection

“…48 Gold black coatings were evaluated for use in pyroelectric detectors by Lehman, who measured a broadband absorption higher than 90% from 1 to 10 mm wavelength range. 49 Ultra black coatings made from an alloy of nickel and platinum have also been reported for use in optical detectors. 50 The performance of this alloy was found to be better than gold black in the visible to near infrared range.…”