JPSS-1 VIIRS Solar Diffuser Witness Sample BRF Calibration Using a Table-Top Goniometer at NASA GSFC

In support of the prelaunch calibration of the Joint Polar Satellite System-1 (JPSS-1) Visible Infrared Imaging Radiometer Suite (VIIRS), the Bidirectional Reflectance Factor (BRF) and Bidirectional Reflectance Distribution Function (BRDF) of a VIIRS solar diffuser (SD) witness sample were determined using the table-top goniometer (TTG) located in the NASA GSFC Diffuser Calibration Laboratory (DCL). The BRF of the sample was measured for VIIRS bands in the reflected solar wavelength region from 410 nm to 2250 nm. The new TTG was developed to extend the laboratorys BRF and BRDF measurement capability to wavelengths from 1600 to 2250 nm and specifically for the VIIRS M11 band centered at 2250 nm. We show the new features and capabilities of the new scatterometer and present the BRF and BRDF results for the incident/scatter test configuration of 0/45 and for a set of angles representing of the VIIRS on-orbit solar diffuser calibration. The BRF and BRDF results of the SD witness were used to assist in finalizing the set of BRF values of J1 VIIRS SD to be used on-orbit. Comparison of the BRF results between the JPSS-1 VIIRS SD witness sample and the flight SD panel was made by varying different sample clocking orientations and by analyzing the ratio of BRF to total hemispherical reflectance in effort to minimize the uncertainty of the extrapolated flight BRF value at 2250 nm. Furthermore, differences between the prelaunch BRF results and those used in the VIIRS on-orbit BRF lookup table were examined to improve the VIIRS BRF calibration for future missions

Characterizations of a KHz Pulsed Laser Detection System

A KHz Pulsed Laser Detection System was developed employing the concept of charge integration with an electrometer, in the NASA Goddard Space Flight Center, Code 618 Calibration Lab for the purpose of using the pulsed lasers for radiometric calibration. Comparing with traditional trans-impedance (current-voltage conversion) detection systems, the prototype of this system consists of a UV-Enhanced Si detector head, a computer controlled shutter system and a synchronized electrometer. The preliminary characterization work employs light sources running in either CW or pulsed mode. We believe this system is able to overcome the saturation issue when a traditional trans-impedance detection system is used with the pulsed laser light source, especially with high peak-power pulsed lasers operating at kilohertz repetition rates (e.g. Ekspla laser or KHz OPO). The charge integration mechanism is also expected to improve the stability of measurements for a pulsed laser light source overcoming the issue of peak-to-peak stability. We will present the system characterizations including signal-to-noise ratio and uncertainty analysis and compare results against traditional trans-impedance detection systems

JPSS-1 VIIRS Solar Diffuser Witness Sample BRF Calibration Using a Table-Top Goniometer at NASA GSFC

In support of the prelaunch calibration of the Joint Polar Satellite System-1 (JPSS-1) Visible Infrared Imaging Radiometer Suite (VIIRS), the Bidirectional Reflectance Factor (BRF) and Bidirectional Reflectance Distribution Function (BRDF) of a VIIRS solar diffuser (SD) witness sample were determined using the table-top goniometer (TTG) located in the NASA GSFC Diffuser Calibration Laboratory (DCL). The BRF of the sample was measured for VIIRS bands in the reflected solar wavelength region from 410 nm to 2250 nm. The new TTG was developed to extend the laboratorys BRF and BRDF measurement capability to wavelengths from 1600 to 2250 nm and specifically for the VIIRS M11 band centered at 2250 nm. We show the new features and capabilities of the new scatterometer and present the BRF and BRDF results for the incident/scatter test configuration of 0/45 and for a set of angles representing of the VIIRS on-orbit solar diffuser calibration. The BRF and BRDF results of the SD witness were used to assist in finalizing the set of BRF values of J1 VIIRS SD to be used on-orbit. Comparison of the BRF results between the JPSS-1 VIIRS SD witness sample and the flight SD panel was made by varying different sample clocking orientations and by analyzing the ratio of BRF to total hemispherical reflectance in effort to minimize the uncertainty of the extrapolated flight BRF value at 2250 nm. Furthermore, differences between the prelaunch BRF results and those used in the VIIRS on-orbit BRF lookup table were examined to improve the VIIRS BRF calibration for future missions

Long-term trends in the burden of edentulism in China over three decades: A Joinpoint regression and age-period-cohort analysis based on the global burden of disease study 2019

BackgroundTo investigate secular trends in edentulism incidence, prevalence, and years lived with disability (YLDs) rates in Chinese men and women from 1990 to 2019.MethodsData were obtained from the Global Burden of Disease Study 2019. The annual percentage change and average annual percentage change were calculated using Joinpoint regression analysis. The age-period-cohort (APC) analysis estimated the independent age, period, and cohort effects.ResultsFrom 1990 to 2019, the crude incidence, prevalence, and YLDs of edentulism in the Chinese population increased year by year, while the age-standardized incidence, prevalence, and YLDs decreased, and the latter was higher in women than in men. The APC analysis showed that the age effect increased in men and women from age 20 to 74 and decreased thereafter. The risk of tooth loss increased with age. However, the relationship was not linear. The temporal effect showed a gradual increase; the risk of missing teeth gradually increased with the changing modern living environment. The cohort effect showed a single decreasing trend, with the early birth cohort having a higher risk of tooth loss than the later birth cohort population. The age, period, and cohort effects were consistent for both sexes.ConclusionAlthough the standardized incidence, prevalence, and YLD rate and cohort effect of dentition loss in China are declining, they are still causing a severe burden to China due to the continued aging of the population and the rising period effect. Despite the decreasing trends of the standardized incidence and prevalence of dentition loss and the rate of YLDs, China should develop more effective oral disease prevention and control strategies to reduce the increasing burden of edentulism in the older adult, especially in older women

Characterizations of a KHz Pulsed Laser Detection System

A KHz Pulsed Laser Detection System was developed employing the concept of charge integration with an electrometer, in the NASA Goddard Space Flight Center, Code 618 Calibration Lab for the purpose of using the pulsed lasers for radiometric calibration. Comparing with traditional trans-impedance (current-voltage conversion) detection systems, the prototype of this system consists of a UV-Enhanced Si detector head, a computer controlled shutter system and a synchronized electrometer. The preliminary characterization work employs light sources running in either CW or pulsed mode. We believe this system is able to overcome the saturation issue when a traditional trans-impedance detection system is used with the pulsed laser light source, especially with high peak-power pulsed lasers operating at kilohertz repetition rates (e.g. Ekspla laser or KHz OPO). The charge integration mechanism is also expected to improve the stability of measurements for a pulsed laser light source overcoming the issue of peak-to-peak stability. We will present the system characterizations including signal-to-noise ratio and uncertainty analysis and compare results against traditional trans-impedance detection systems

Test and Assessment of a New Quantum Cascade Laser at 23 μm for Applications in the Longwave Infrared Region

The total outgoing longwave radiation emitted from the earth-atmosphere system to the outer space is in 3 - 100 µm wavelength band. Development of satellite instrumentations for the outgoing longwave radiation depends on material study, sensor research, and instrument tests in the wavelength region of interest. Beyond 20 µm, the availability of a laser source with the average output power \u3e several mW is a challenge in the commercial market. In the presentation, we report the results of testing and assessing a quantum cascade laser (QCL) at 23 µm (430 cm-1) with average power \u3c 1 mW. It operates in a pulsed multimode around LN2 temperature in a cryostat. The QCL at 23 µm has been installed successfully, and was tested using a LiNbO3 pyroelectric detector with some preliminary results. To further stabilize the output of the laser in the cryogenic temperature, a recommended transfer line and a vertical withdrawal container are equipped to the laser cryostat. And a more sensitive and efficient detection is required to measure the output power using a focusing optics for the beam divergence of 60° and 40° in vertical and horizontal directions, respectively. To improve detection, a blocked impurity band (BIB) detector is planning to be applied in the next test, as well as a Deuterium Triglycine Sulfate (DTGS) pyroelectric detector that is recommended by the manufacturer. The test results of the QCL at 23 μm will be compared with that of the power output at the same wavelength from a synchrotron radiation facility. Eventually, it will be integrated with the Complete Hemispherical Infrared Laser-based Reflectometer (CHILR) and the Infrared Laser-based Gonio-reflectometer (ILGR) at NIST to support measurement in the longwave infrared region

Measuring Linearity of Detector Spectral Responsibity at Ultra-Low Incident Powers

A LED-driven integrating sphere uniform light source within a light-tight enclosure was used to characterize the linearity of spectral responsivity for detectors at Pico-watt and sub Pico-watt incident power levels over a wavelength range from 405 nm to 1550 nm. A UV-enhanced Si detector, a Std-InGaAs detector and an Ex-InGaAs detector were used with a pre-amplifier SR-570 and a lock-in amplifier SR-830. The results of spectral responsivity linearity and measurement uncertainty at low incident power levels will be presented and analyzed. Results from the different detectors will be compared, and the measurement methodology will be discussed

New Capabilities of Diffuser Calibration Lab at GSFC NASA to Support Remote Sensing Instrumentation

The on-orbit calibration of earth observation satellite sensors with solar diffuser (SD) is significantly of importance to obtain high quality sensor data with low uncertainty for the reflective solar band (RSB). Much effort has been devoted to the pre-launch calibration of SD, and associated components. In those calibrations, the BRDF measurement of SD, as well as the BTDF measurement for associated components, are required to be conducted at different incident angles due to the solar season on-orbit and viewing from various angles based on the instrument geometry with high accuracy. To satisfy different requirements for SD related calibrations, the new diffuser calibration facility is established with two kinds of scatterometer instruments, one is a table-top based goniometer, and the other is a robot-based scatterometer. For the SD calibration in the RSB, the light sources for the system are currently equipped with a 20 W supercontinuum fiber laser with the spectral range from 400 nm to 2500 nm, and two laser diode driven plasma lamp sources covering wavelengths from 200 nm to 900 nm. The detection systems corresponding to the same spectral range of interest are composed of Si and extended InGaAs (EIGA) detectors with low NEP down to 10-15 and 7 × 10-14 W/(Hz)1/2, respectively, which are designed to have two light collection options, with/without input integrating sphere. The development of the table-top based goniometer has reached the final stage of optimization and alignment for sample manipulation and detector rotation, meanwhile the major component, a 6-axis robot-arm, for the robot-based scatterometer was also delivered recently. The light source tests on spectral output and short term stability were carried out, and the preliminary results will be presented together with discussion of practical applications

New Capabilities of Diffuser Calibration Lab at GSFC NASA to Support Remote Sensing Instrumentation

The on-orbit calibration of earth observation satellite sensors with solar diffuser (SD) is significantly of importance to obtain high quality sensor data with low uncertainty for the reflective solar band (RSB). Much effort has been devoted to the pre-launch calibration of SD, and associated components. In those calibrations, the BRDF measurement of SD, as well as the BTDF measurement for associated components, are required to be conducted at different incident angles due to the solar season on-orbit and viewing from various angles based on the instrument geometry with high accuracy. To satisfy different requirements for SD related calibrations, the new diffuser calibration facility is established with two kinds of scatterometer instruments, one is a table-top based goniometer, and the other is a robot-based scatterometer. For the SD calibration in the RSB, the light sources for the system are currently equipped with a 20 W supercontinuum fiber laser with the spectral range from 400 nm to 2500 nm, and two laser diode driven plasma lamp sources covering wavelengths from 200 nm to 900 nm. The detection systems corresponding to the same spectral range of interest are composed of Si and extended InGaAs (EIGA) detectors with low NEP down to 10-15 and 7 × 10-14 W/(Hz)1/2, respectively, which are designed to have two light collection options, with/without input integrating sphere. The development of the table-top based goniometer has reached the final stage of optimization and alignment for sample manipulation and detector rotation, meanwhile the major component, a 6-axis robot-arm, for the robot-based scatterometer was also delivered recently. The light source tests on spectral output and short term stability were carried out, and the preliminary results will be presented together with discussion of practical applications

New Capability for Evaluating the Emissivity of Large Aperture Infrared Blackbodies

The Laser Infrared Reflectometry (LIR) laboratory at NIST includes a facility for the measurement of very low reflectance levels of materials and cavities in the infrared such as those used in high accuracy radiometers and blackbody reference sources. The key elements of the facility are integrating sphere systems, which are used to collect the reflected light from the samples and cavities that are measured. For cavity instruments, the effective emissivity or absorptance can be obtained simply by subtraction of the reflectance from unity. The first sphere system, in operation for the last 5 years, the Complete Hemispherical Infrared Laser-based Reflectometer (CHILR), has been used to examine a large number of blackbody and radiometer cavities. However, it is limited to the measurement of cavities with aperture diameters not exceeding 50 mm. There has been an unmet need for the characterization of larger aperture cavities. This presentation reports on the status of a new sphere system designed for accurate measurements of cavities with apertures up to 200 mm in diameter. The core of a new setup is a 50 cm integrating sphere with an integrated substitution / port reduction wheel and means for mapping the spatial distribution of reflectance of the object under test. We describe the concept and performance goals of the new capability. We present the first results of its evaluation, including coating properties and throughput evaluation results, which allow estimates of the signal to noise ratio for different laser sources, as well as the minimum discernable reflectance levels of targets. While full implementation of the new capability may require more time and resources, it is available to support the critical needs of the community. We acknowledge the National Oceanic and Atmospheric Administration (NOAA) Joint Polar Satellite System (JPSS) Program for its support