Aaron J. Pearlman

A versatile waveguide source of photon pairs for chip-scale quantum information processing

We demonstrate a bright, bandwidth-tunable, quasi-phase-matched single-waveguide source generating photon pairs near 900 nm and 1300 nm. Two-photon coincidence spectra are measured at a range of operating temperatures of a periodically-poled KTiOPO(4) (PPKTP) waveguide, which supports both type-0 and type-II spontaneous parametric down-conversion. We map out relative contributions of two-photon to one-photon fluorescence for a range of operating parameters. Such a versatile device is highly promising for future chip-scale quantum information processing.

Resolution and sensitivity of a Fabry-Perot interferometer with a photon-number-resolving detector

With photon-number resolving detectors, we show compression of interference fringes with increasing photon numbers for a Fabry-Perot interferometer. This feature provides a higher precision in determining the position of the interference maxima compared to a classical detection strategy. We also theoretically show supersensitivity if N-photon states are sent into the interferometer and a photon-number resolving measurement is performed.

Towards post-launch validation of GOES-R ABI SI traceability with high-altitude aircraft, small near surface UAS, and satellite reference measurements

The GOES-R field campaign (planned for April – June 2017) is focused to support post-launch validation of the Advanced Baseline Imager (ABI) and Geostationary Lightning Mapper (GLM). Great emphasis has been placed in the development of methodologies to achieve the ABI GOES-R field campaign primary objective - validation of ABI L1b spectral radiance observations to ensure the SI traceability established pre-launch. An integrated approach using high altitude aircraft, near surface UAS, and satellite reference measurements was developed to achieve the ABI validation objectives of the GOES-R field campaign. The high-altitude aircraft measurements coupled with special ABI collections are planned to provide the primary pathway (direct comparison) to validate ABI SI traceability of all ABI operational detectors. Near surface Unmanned Aircraft Systems (UAS) are planned to provide a secondary pathway to validate ABI SI traceability through coincident near surface measurements of Earth validation targets using the Earth’s surface as a reference (indirect comparison). Satellite reference measurements obtained through special ABI collections and Simultaneous Nadir Overpass (SNO) of reference sensors will also provide a secondary pathway to validate ABI SI traceability. A detailed description of each validation approach, the critical components, and the preliminary expected uncertainties will be presented. The combined collections offer advanced post-launch validation capabilities and foster new perspectives for science teams during the post-launch validation and monitoring of NOAA’s next generation of operational environmental satellites.

Initial design and performance of the near surface unmanned aircraft system sensor suite in support of the GOES-R field campaign

One of the main objectives of the Geostationary Operational Environmental Satellite R-Series (GOES-R) field campaign is to validate the SI traceability of the Advanced Baseline Imager. The campaign plans include a feasibility demonstration study for new near surface unmanned aircraft system (UAS) measurement capability that is being developed to meet the challenges of validating geostationary sensors. We report our progress in developing our initial systems by presenting the design and preliminary characterization results of the sensor suite. The design takes advantage of off-the-shelf technologies and fiber-based optical components to make hemispheric directional measurements from a UAS. The characterization results -- including laboratory measurements of temperature effects and polarization sensitivity -- are used to refine the radiometric uncertainty budget towards meeting the validation objectives for the campaign. These systems will foster improved validation capabilities for the GOES-R field campaign and other next generation satellite systems.

The GOES-R Advanced Baseline Imager: detector spectral response effects on thermal emissive band calibration

The Advanced Baseline Imager (ABI) will be aboard the National Oceanic and Atmospheric Administration’s Geostationary Operational Environmental Satellite R-Series (GOES-R) to supply data needed for operational weather forecasts and long-term climate variability studies, which depend on high quality data. Unlike the heritage operational GOES systems that have two or four detectors per band, ABI has hundreds of detectors per channel requiring calibration coefficients for each one. This increase in number of detectors poses new challenges for next generation sensors as each detector has a unique spectral response function (SRF) even though only one averaged SRF per band is used operationally to calibrate each detector. This simplified processing increases computational efficiency. Using measured system-level SRF data from pre-launch testing, we have the opportunity to characterize the calibration impact using measured SRFs, both per detector and as an average of detector-level SRFs similar to the operational version. We calculated the spectral response impacts for the thermal emissive bands (TEB) theoretically, by simulating the ABI response viewing an ideal blackbody and practically, with the measured ABI response to an external reference blackbody from the pre-launch TEB calibration test. The impacts from the practical case match the theoretical results using an ideal blackbody. The observed brightness temperature trends show structure across the array with magnitudes as large as 0.1 K for and 12 (9.61 µm), and 0.25 K for band 14 (11.2 µm) for a 300 K blackbody. The trends in the raw ABI signal viewing the blackbody support the spectral response measurements results, since they show similar trends in bands 12 (9.61µm), and 14 (11.2 µm), meaning that the spectral effects dominate the response differences between detectors for these bands. We further validated these effects using the radiometric bias calculated between calibrations using the external blackbody and another blackbody, the ABI on-board calibrator. Using the detector-level SRFs reduces the structure across the arrays but leaves some residual bias. Further understanding of this bias could lead to refinements of the blackbody thermal model. This work shows the calibration impacts of using an average SRF across many detectors instead of accounting for each detector SRF independently in the TEB calibration. Note that these impacts neglect effects from the spectral sampling of Earth scene radiances that include atmospheric effects, which may further contribute to artifacts post-launch and cannot be mitigated by processing with detector-level SRFs. This study enhances the ability to diagnose anomalies on-orbit and reduce calibration uncertainty for improved system performance.

Number-resolving, single photon detection with no deadtime

We present a new scheme of a photon-resolving measurement with a superconducting microbolometer. Based on known ldquoinstrumental functionrdquo of the microbolometer, we convert its analog output into a digitized record of photon detections without deadtime.

Landsat 9 Thermal Infrared Sensor 2 pre-launch characterization: initial imaging and spectral performance results.

The Thermal Infrared Sensor-2 (TIRS-2) aboard Landsat 9 will continue Landsat’s four decade-long legacy of providing moderate resolution thermal imagery from low earth orbit (at 705 km) for environmental applications. Like the Thermal Infrared Sensor aboard Landsat 8, it is a pushbroom sensor with a cross-track field of view of 15° and provides two spectral channels at 10.8 and 12 μm. To ensure radiometric, spatial, and spectral performance, a comprehensive pre-launch testing program is being conducted at NASA Goddard Space Flight Center at the component, subsystem, and instrument level. This paper will focus on the results from the subsystem level testing where the instrument is almost completely assembled. This phase of testing is specifically designed to assess imaging performance including focus and stray light rejection, but is also used to provide a preliminary assessments of spatial and spectral performance. The calibration ground support equipment provides a flexible blackbody illumination source and optics to conduct these tests. The spectral response test setup has its own illumination source outside the chamber that propagates through the calibration ground support equipment in an optical configuration designed for this purpose. This test configuration with the calibration ground support equipment and TIRS-2 subsystem in the thermal vacuum chamber enables a large range of illumination angles for stray light measurements. The results show that TIRS-2 performance is expected to meet all of its performance requirements with few waivers and deviations.

Characterization of GOES-16 ABI detector-level uniformity from post-launch north south scan collections of several earth targets.

The GOES-16 Advanced Baseline Imager (ABI) is the first of four of NOAAs new generation of Earth imagers. The ABI uses large focal plane arrays (100s to 1000s of detectors per channel), which is a significant increase in the number of detectors per channel compared to the heritage GOES O-P imagers (2 to 8 detectors per channel). Due to the increase in number of detectors there is an increased risk of imaging striping in the L1b & L2+ products. To support post-launch striping risk mitigation strategies, customized ABI special scans (ABI North South Scans - NSS) were developed and implemented in the post-launch checkout validation plan. ABI NSS collections navigate each detector of a given channel over the same Earth target enabling the characterization of detector-level performance evaluation. These scans were used to collect data over several Earth targets to understand detector-to-detector uniformity as function of a broad set of targets. This effort will focus on the data analysis, from a limited set of NSS data (ABI Ch. 1), to demonstrate the fundamental methodology and ability to conduct post-launch detector-level performance characterization and advanced relative calibrations using such data. These collections and results provide critical insight in the development of striping risk mitigation strategies needed in the GOES-R era to ensure L1b data quality to the GOES user community.

Validation of GOES-16 ABI reflective solar band calibration through reanalysis and comparison with field campaign data.

The Advanced Baseline Imager (ABI) is a critical instrument onboard GOES-16 which provides high quality Reflective Solar Bands (RSB) data though radiometric calibration using onboard solar diffuser. Intensive field campaign for post-launch validation of the ABI L1B spectral radiance observations was carried out during March-May, 2017 to ensure the SI traceability of ABI. In this paper, radiometric calibrations of the five RSBs of ABI are evaluated with the measurements by Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) onboard the high-altitude aircraft ER2. The ABI MESO data processed by the vendor with ray-matching to AVIRIS-NG during the field campaign was compared with the AVIRIS-NG measurements for radiometric bias evaluation. Furthermore, there were several implementations and updates in the solar calibration of ABI RSBs which resulted in different versions of detector gains and nonlinear calibration factors. These calibrations included the calibration by the operational ground processing system, by vendor and the calibration with updated nonlinear calibration factor table for striping mitigation and accounting for the integration time difference between solar calibration and Earth view. The North-South Scan (NSS) field campaign data of ABI were re-processed with these calibration coefficients to quantitatively evaluate the detector uniformity change. The detector uniformity difference are traced back to the difference in the implementation of the solar calibration.

Independent validation of the advanced baseline imager (ABI) on NOAA's GOES-16: post-launch ABI airborne science field campaign results.

A primary objective of the GOES-16 post-launch airborne science field campaign was to provide an independent validation of the SI traceability of the Advanced Baseline Imager (ABI) spectral radiance observations for all detectors post-launch. The GOES-16 field campaign conducted sixteen validation missions (March to May 2017), three of which served as the primary ABI validation missions and are the focus of this work. These validation missions were conducted over ideal Earth targets with an integrated set of well characterized hyperspectral reference sensors aboard a high-altitude NASA ER-2 aircraft. These missions required ABI special collections (to scan all detectors over the earth targets), unique aircraft maneuvers, coordinated ground validation teams, and a diplomatic flight clearance with the Mexican Government. This effort presents a detector-level deep-dive analysis of data from the targeted sites using novel geospatial database and image abstraction techniques to select and process matching pixels between ABI and reference instruments. The ABI reflective solar band performance (ABI bands 1-3 & 5-6) was found to have biases within 5 % radiance for all bands, except band 2; and the ABI thermal emissive band performance was found to have biases within 1 K for all bands. Additional inter-comparison results using targeted ABI special collections with the Low Earth Orbit reference sensor S-NPP/VIIRS will also be discussed. The reference data collected from the campaign has demonstrated that the ABI SI traceability has been validated post-launch and established a new performance benchmark for NOAA’s next generation geostationary Earth observing instrument products.