Micro-DRIFTS for small area hyper-black spectroscopy.

We have developed a low-cost micro-diffuse reflectance infrared Fourier transform spectroscopic (micro-DRIFTS) setup for measuring the reflectance of small area diffuse samples. The system performance is characterized and then demonstrated on small area vertically aligned carbon nanotube (VACNT) samples. We find that our system can measure samples with a spatial resolution of approximately 140 µm with sensitivities of 10s of ppm in the 2 µm - 18 µm spectral window.

High-accuracy room temperature planar absolute radiometer based on vertically aligned carbon nanotubes.

We have developed a planar absolute radiometer for room temperature (PARRoT) that will replace the legacy C-series calorimeter as the free-space continuous-wave laser power detector standard at the National Institute of Standards and Technology (NIST). This instrument will lower the combined relative expanded measurement uncertainty (k = 2) from 0.84 % to 0.

Noise characteristics of thermistors: Measurement methods and results of selected devices.

As part of the development of a spectrally uniform room-temperature absolute radiometer, we have studied the electrical noise of several bulk chip thermistors in order to estimate the noise floor and optical dynamic range. Understanding the fundamental limits of the temperature sensitivity leads inevitably to studying the noise background of the complex electro-thermal system. To this end, we employ a measurement technique based on alternating current synchronous demodulation.

Planar hyperblack absolute radiometer.

The absolute responsivity of a planar cryogenic radiometer fabricated from micromachined silicon and having carbon nanotubes, as the absorber and thermistor were measured in the visible and far infrared (free-field terahertz) wavelength range by means of detector-based radiometry. The temperature coefficient of the thermistor near 4.8 K and noise equivalent power were evaluated along with independent characterization of the window transmittance and specular reflectance of the nanotube absorber.

Extending single-photon optimized superconducting transition edge sensors beyond the single-photon counting regime.

Typically, transition edge sensors resolve photon number of up to 10 or 20 photons, depending on the wavelength and TES design. We extend that dynamic range up to 1000 photons, while maintaining sub-shot noise detection process uncertainty of the number of detected photons and beyond that show a monotonic response up to ≈ 6 · 10(6) photons in a single light pulse. This mode of operation, which heats the sensor far beyond its transition edge into the normal conductive regime, offers a technique for connecting single-photon-counting measurements to radiant-power measurements at picowatt levels.