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In this work, we have studied the possibility of using a MEMS accelerometer to generate seeds for a secure cryptosystem. The noise signal generated by the accelerometer at rest has been studied and, after a post-processing process, has been used to generate the initial parameters of a stream cipher based on a piecewise linear chaotic map. The encryption algorithm has been implemented in a Xilinx Virtex 7 FPGA achieving a throughput of 200 Mbps using 390 LUTS. The resulting sequences generated by this system have been subjected to the NIST randomness tests, passing all of them, indicating that the whole encryption system is secure.

Specular gloss is the fraction of light reflected in the specular direction for specified incident and receptor apertures, it is the perception by an observer of the mirror-like appearance of a surface. The measurement of specular gloss consists of comparing the luminous reflectance from a test sample to that from a calibrated gloss standard which generally is a polished piece of black glass, under the same experimental conditions. Gloss is a dimensionless quantity whose accurate determination requires standardized experimental conditions such as spectral distribution of the incident beam of light, incident and viewing angles, and a gloss standard. The Shanghai Institute of Measurement and Testing Technology (SIMT) provides test service to calibrate gloss reference standards. This facility is built around a reference goniophotometer, containing an instrument that measures flux as a function of angles of illumination or observation and a primary gloss standard, which is a piece of three wedges of highly polished, high-quality optical glass. The system has an overall (k=2) uncertainty of 0.5 Gloss Unit(GU). The service offers calibration measurements of working gloss standards at the geometries of 20°, 60°, and 85°, in compliance with the ISO 2813 and the ASTM D523 documentary standards. This article describes a bilateral comparison of specular gloss scales between SIMT and the National Institute of Standards and Technology (NIST) that has been performed. The results of this comparison show agreement within the combined uncertainties for the measurement of specular gloss of highly polished black glass.

The relative spectral response (RSR) characterization of the JPSS-1 VIIRS spectral bands has achieved at launch status in the VIIRS Data Analysis Working Group February 2016 Version 2 RSR release. The Version 2 release improves upon the June 2015 Version 1 release by including December 2014 NIST TSIRCUS spectral measurements of VIIRS VisNIR bands in the analysis plus correcting CO2 influence on the band M13 RSR. The T-SIRCUS based characterization is merged with the summer 2014 SpMA based characterization of VisNIR bands (Version 1 release) to yield a fused RSR for these bands, combining the strengths of the T-SIRCUS and the SpMA measurement systems. The M13 RSR is updated by applying a model-based correction to mitigate CO2 attenuation of the SpMA source signal that occurred during M13 spectral measurements. The Version 2 release carries forward the Version 1 RSR for those bands that were not updated (M8-M12, M14-M16AB, I3-I5, DNBMGS). The Version 2 release includes band average (overall detectors and subsamples) RSR plus supporting RSR for each detector and subsample. The at-launch band average RSR have been used to populate Look-Up Tables supporting the sensor data record and environmental data record at-launch science products. Spectral performance metrics show that JPSS-1VIIRS RSR are compliant on specifications with a few minor exceptions. The Version 2 release, which replaces the Version 1 release, is currently available on the password-protected NASA JPSS-1 eRooms under EAR99 control.

Despite the advancements of fingerprint recognition in 2-D and 3-D domain, authenticating deformed/post-mortem fingerprints continue to be an important challenge. Prior cleansing and reconditioning of the deceased finger is required before acquisition of the fingerprint. The victim’s finger needs to be precisely and carefully operated by a medium to record the fingerprint impression. This process may damage the structure of the finger, which subsequently leads to higher false rejection rates. This paper proposes a non-invasive method to perform 3-D deformed/post-mortem finger modeling, which produces a 2-D rolled equivalent fingerprint for automated verification. The presented novel modeling method involves masking, filtering, and unrolling. Computer simulations were conducted on finger models with different depth variations obtained from Flashscan3D LLC. Results illustrate that the modeling scheme provides a viable 2-D fingerprint of deformed models for automated verification. The quality and adaptability of the obtained unrolled 2-D fingerprints were analyzed using NIST fingerprint software. Eventually, the presented method could be extended to other biometric traits such as palm, foot, tongue etc. for security and administrative applications.

Terahertz metrology is becoming more and more important along with the fast development of terahertz technology. This paper reviews the research works of the groups from the physikalisch-technische bundesanstalt (PTB), National institute of standards and technology (NIST), National physical laboratory (NPL), National institute of metrology (NIM) and some other research institutes. The contents mainly focus on the metrology of parameters of power, frequency, spectrum and pulse. At the end of the paper, the prospect of terahertz metrology is predicted.

We report the initial results of a recent bilateral comparison of linewidth or critical dimension (CD) calibrations on photomask line features between two national metrology institutes (NMIs): the National Institute of Standards and Technology (NIST) in the United States and the Physikalisch-Technische Bundesanstalt (PTB) in Germany. For the comparison, a chrome on glass (CoG) photomask was used which has a layout of line features down to 100 nm nominal size. Different measurement methods were used at both institutes. These included: critical dimension atomic force microscopy (CD-AFM), CD scanning electron microscopy (CD-SEM) and ultraviolet (UV) transmission optical microscopy. The measurands are CD at 50 % height of the features as well as sidewall angle and line width roughness (LWR) of the features. On the isolated opaque features, we found agreement of the CD measurements at the 3 nm to 5 nm level on most features – usually within the combined expanded uncertainties of the measurements.

A Shack-Hartmann wave-front sensor system has been used to measure a set of plano-convex lenses at two different times, separated by almost 2 years. The plano-convex lenses were selected to cover a range of powers and apertures relevant to intraocular lenses, and were measured at two different orientations. The results demonstrate the high temporal stability of the measurement system, as well as of the glass standard. In addition, both times the effective focal lengths of the standards were measured using a NIST traceable nodal slide bench, and the center thicknesses were measured using low-coherence interferometer. The spherical aberration and the effective focal length results are analyzed for statistically significant changes. The results are also compared to the Zemax models of the standards.

This is the fourth part of a series of tutorial papers discussing various causes of measurement uncertainty in scanned particle beam instruments, and some of the solutions researched and developed at NIST and other research institutions. Scanned particle beam instruments especially the scanning electron microscope (SEM) have gone through tremendous evolution to become indispensable tools for many and diverse scientific and industrial applications. These improvements have significantly enhanced their performance and made them far easier to operate. But, the ease of operation has also fostered operator complacency. In addition, the user-friendliness has reduced the apparent need for extensive operator training. Unfortunately, this has led to the idea that the SEM is just another expensive “digital camera” or another peripheral device connected to a computer and that all of the problems in obtaining good quality images and data have been solved. Hence, one using these instruments may be lulled into thinking that all of the potential pitfalls have been fully eliminated and believing that, everything one sees on the micrograph is always correct. But, as described in this and the earlier papers, this may not be the case. Care must always be taken when reliable quantitative data are being sought. The first paper in this series discussed some of the issues related to signal generation in the SEM, including instrument calibration, electron beam-sample interactions and the need for physics-based modeling to understand the actual image formation mechanisms to properly interpret SEM images. The second paper has discussed another major issue confronting the microscopist: specimen contamination and methods to eliminate it. The third paper discussed mechanical vibration and stage drift and some useful solutions to mitigate the problems caused by them, and here, in this the fourth contribution, the issues related to specimen “charging” and its mitigation are discussed relative to dimensional metrology.

We present a post-processing free quantum random number generator (QRNG) based on silicon nanocrystals (Si-NCs) LEDs as a source of randomness. The relatively simple setup for data extraction, a negligible bias measured from the datasets and applying no post-processing operations to the raw data are the main advantages of this QRNG . The obtained bit sequences pass all the NIST tests and the highest bit-rate achieved is 0.6 Mbps.

The concern in this paper is an important category of applications of open-set speaker identification in criminal investigation, which involves operating with short and varied duration speech. The study presents investigations into the adverse effects of such an operating condition on the accuracy of open-set speaker identification, based on both GMMUBM and i-vector approaches. The experiments are conducted using a protocol developed for the identification task, based on the NIST speaker recognition evaluation corpus of 2008. In order to closely cover the real-world operating conditions in the considered application area, the study includes experiments with various combinations of training and testing data duration. The paper details the characteristics of the experimental investigations conducted and provides a thorough analysis of the results obtained.

Segmentation and identification of compounds or materials existing in a scene is a crucial process. Hyperspectral sensors operating in different regions of the electromagnetic spectrum are able to quantify spectral characteristics of materials in different states. Due to the fact that some chemical compounds in gas state have insignificant light reflectance characteristics in visible region of the spectrum, imaging sensors operating in infrared regions are needed to sense energy absorbency characteristics of these compositions. The present study proposes a novel method for detection of flammable gases in long-wave infrared hyperspectral images. Proposed method begins with Black-Body radiation curve compensation. Since a priori information regarding the compounds in the scene is not always available, endmember spectral signatures are extracted with VCA hyperspectral unmixing algorithm. Afterwards, endmember signatures are matched with infrared energy absorbance signature of the target gas obtained from NIST (National Institute of Standards and Technology) Material Measurement Laboratory. Finally, concentration of target signature at each image pixel is detected by means of endmember abundance maps. The performance of the approach is compared with that of similarity measure based gas detection methods. It is observed that the proposed technique removes the need for an external threshold setting while providing better resolvability of the gasses.

A new definition is proposed for the calibration of Night Vision Goggle (NVG) gains. This definition is based on the measurement of radiometric input and output quantities of the NVG. While the old definition used the “equivalent fL” which is a non SI traceable luminance unit, the new definition utilizes the radiance quantities that are traceable to the SI units through NIST standards. The new NVG gain matches the previous one as a result of the application of a correction coefficient originating from the conversion of the radiance to luminance units. The new definition was tested at the NIST Night Vision Calibration Facility and the measurement results were compared to the data obtained with a Hoffman Test Set Model ANV-126. Comparing the radiometric quantities of the Hoffman Test Set and those measured by the NIST transfer standard radiometer, indicates that the observed differences up to 15% were due to the calibration and experimental errors of the ANV-126 Test Set. In view of different spectral characteristics of luminophores that can be utilized in the NVG design, the simulation of the NVG output for gain measurement was performed. The NVG output was simulated with a sphere-based source using different LEDs and the measured gain was compared to that obtained with the ANV-126 internal luminance meter. The NVG gain uncertainty analysis was performed for the Type A, B, and C goggles.

Quantitative electron-excited x-ray microanalysis by scanning electron microscopy/silicon drift detector energy dispersive x-ray spectrometry (SEM/SDD-EDS) is capable of achieving high accuracy and high precision equivalent to that of the high spectral resolution wavelength dispersive x-ray spectrometer even when severe peak interference occurs. The throughput of the SDD-EDS enables high count spectra to be measured that are stable in calibration and resolution (peak shape) across the full deadtime range. With this high spectral stability, multiple linear least squares peak fitting is successful for separating overlapping peaks and spectral background. Careful specimen preparation is necessary to remove topography on unknowns and standards. The standards-based matrix correction procedure embedded in the NIST DTSA-II software engine returns quantitative results supported by a complete error budget, including estimates of the uncertainties from measurement statistics and from the physical basis of the matrix corrections. NIST DTSA-II is available free for Java-platforms at: http://www.cstl.nist.gov/div837/837.02/epq/dtsa2/index.html).

ASTRI SST-2M is the end-to-end prototype telescope under development by the Italian National Institute of Astrophysics, INAF, proposed for the investigation of the highest-energy gamma-ray band in the framework of the Cherenkov Telescope Array, CTA. The ASTRI SST-2M prototype will be installed in Italy at the INAF station located at Serra La Nave on Mount Etna during Fall 2014. The calibration and scientific validation phase will start soon after. The calibration of a Cherenkov telescope includes several items and tools. The ASTRI SST- 2M camera is equipped with an internal fiber illumination system that allows to perform the relative calibration through monitoring of gain and efficiency variations of each pixel. The absolute calibration of the overall system, including optics, will take advantage from auxiliary instrumentation, namely UVscope and UVSiPM, two small-aperture multi-pixels photon detectors NIST calibrated in lab. During commissioning phase, to measure the main features of ASTRI SST-2M, as its overall spectral response, the main telescope and the auxiliary UVscope-UVSiPM will be illuminated simultaneously by a spatially uniform flux generated by a ground-based light source, named Illuminator, placed at a distance of few hundreds meters. Periodically, during clear nights, the flux profiles of a reference star tracked simultaneously by ASTRI SST-2M and UVscope-UVSiPM will allow to evaluate the total atmospheric attenuation and the absolute calibration constant of the ASTRI SST-2M prototype. In this contribution we describe the auxiliary UVscope-UVSiPM and Illuminator sub-system together with an overview of the end-to-end calibration procedure foreseen for the ASTRI SST-2M telescope prototype.

Establishing improved spectrophotometric standards is important for a broad range of missions and is relevant to many astrophysical problems. ACCESS, Absolute Color Calibration Experiment for Standard Stars", is a series of rocket-borne sub-orbital missions and ground-based experiments designed to enable improvements in the precision of the astrophysical flux scale through the transfer of absolute laboratory detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35 - 1.7μm bandpass. This paper describes the payload status, sub-system testing, and data transfer for the ACCESS instrument.

Methods for making total and diffuse directional/hemispherical reflectance measurements in the shortwave to longwave infrared using an integrating sphere are described. The sphere is a commercial, off-the-shelf optical device with its sample port at the bottom, which is essential for examining powdered samples without using a cover glass. The reflectance spectra of recently-developed National Institute of Standards and Technology (NIST, USA) infrared reflectance standards have been measured using the sphere. Reflectance spectra of other materials such as Spectralon and Infragold were also measured. The relative systematic error for the total reflectance measurements is estimated to be on the order of 3%, and random measurement error for multiple samples of each material is on the order of 0.5%.

In order to perform radiance and luminance level measurements of night-vision-goggle (NVG) test instruments, NIST developed new-generation transfer-standard radiometers (TR). The new TRs can perform low-level radiance and luminance measurements with SI traceability and low uncertainty. The TRs were calibrated against NIST detector/radiometer standards holding the NIST photometric and radiometric scales. An 815 nm diode laser was used at NIST for the radiance responsivity calibrations. A spectrally flat (constant) filter correction was made for the TRs to correct the spectral responsivity change of the built-in Si photodiode for LEDs peaking at different wavelengths in the different test sets. The radiance responsivity transfer to the test instruments (test-sets) is discussed. The radiance values of the test instruments were measured with the TRs. The TRs propagate the traceablity to the NIST detector-based reference scales. The radiance uncertainty obtained from three TR measurements was 4.6 % ( 𝑘 =2) at a luminance of 3.43 x 10 -4 cd/m 2 . The output radiance of the previously used IR sphere source and the radiance responsivity of a previously used secondary standard detector unit, which was originally calibrated against an IR sphere source, were also measured with the TRs. The performances of the NVG test instruments were evaluated and the manufacturer produced radiance and luminance levels were calibrated with SI/NIST traceability.

The NIST Extreme Ultraviolet (EUV) Reflectometry Facility was designed in the 1990s to accommodate the largest multilayer optics envisioned at that time. However, with increasing power requirements for an EUV scanner, source collection optics have grown larger and more steeply curved than the original design would allow. To accommodate these changes, the mechanical and operational parameters of the facility have been upgraded. To access the entire surface of a larger optic, an auxiliary off-axis rotation stage has been installed allowing an increase in maximum optic size from 350 mm to 450 mm. Likewise, to deal with the deeper sags and steeper slopes of these optics, we have had to significantly expand our data analysis capabilities. In order to make these measurements, the incident radiation is reflected out of the vertical plane, allowing for measurements of effectively unpolarized radiation, an advantage for EUV lithography optics such as source collectors.

A novel design of X-ray optical system - concentrator for astrophysical rocket experiment is investigated. The proposed system is based on four modules with Kirkpatrick-Baez (KB) configuration allowing usage of multi-foil mirrors arranged to parabolic profile. The KB modules are supplemented by rotationally symmetrical parabolic segments. This X-ray optical system effectively uses a circular aperture. The KB modules are placed in four quadrants while the segments are set into a Cartesian cross between the KB modules. Studied optical system is under consideration for the student rocket experiment of University of Colorado that should verify function of NIST’s energy-dispersive detector based on Transition Edge Sensors (TES microcalorimeters).

A neutron hardened x-ray streak camera has been used to report x-ray burn duration and time of peak emission from imploding ICF capsules at the National Ignition Facility with

We describe the robotic optical scatter instrument (ROSI), a new robotic arm-based goniometer for in-plane and outof- plane reflectance and bidirectional reflectance distribution function (BRDF) measurements of surfaces. The goniometer enables BRDF measurements to be made at nearly any combination of incident and scattering angles, without obstruction from frames or cradles that occur in traditional goniometers made of nested rotation stages. We present exploratory measurements of in-plane and hemispherically-scanned out-of-plane BRDF on a sintered white polytetrafluoroethylene (PTFE) sample using a supercontinuum fiber laser-based tunable light source operated at a wavelength of 550 nm, in order to demonstrate the capabilities of the system. An initial assessment of uncertainties is presented.

A tunable, intensity-stabilized, quasi-continuous wave (CW) laser system, patterned after the Spectral Irradiance and Radiance Responsivity Calibrations using Uniform Sources (SIRCUS) system at the National Institute of Standards and Technology (NIST) 1, has been installed and is being tested in the NASA Goddard Space Flight Center (GSFC) Code 618 Biospheric Sciences Laboratory’s Calibration Facility. This system is referred to as SIRCUS-G (SIRCUS-Goddard). The tunable output of the laser system is fiber-fed to a 76.2 cm diameter integrating sphere lined with Spectralon. The uniform radiance light emitted from the integrating sphere is used in system-level radiometric responsivity characterizations and wavelength calibrations of remote sensing instruments. The primary radiance reference standards in the responsivity characterizations are a three-element Si trap radiometer for the visible and near infrared and a radiometer employing an InGaAs detector. Both radiometers have been calibrated by NIST. These radiometers are located at the exit port of the Spectralon coated integrating sphere. In addition, a set of three radiometers are mounted on the 76.2 cm integrating sphere’s wall ports to monitor source radiance and to provide real-time sphere radiance data during the calibrations of remote sensing instruments. These monitor radiometers provide spectral coverage from 300nm to near 2500nm. This paper presents the results of our characterization of the performance of these monitor radiometers. Results are presented and discussed on monitor radiometer short- and long-term system stability, noise level, and total measurement uncertainty.

The scanning electron microscope (SEM) has gone through a tremendous evolution to become a critical tool for many and diverse scientific and industrial applications. The improvements that have been made have significantly improved the overall SEM performance and have made the instrument far easier to operate. But, ease of operation also fosters operator complacency. In addition, the user friendliness has reduced the “apparent” need for more thorough operator training for using of these instruments. Therefore, this overall attitude has fostered the concept that the SEM is just another expensive digital camera or another peripheral device for a computer. Hence, a person using the instrument may be lulled into thinking that all of the potential pitfalls have been eliminated and they believe everything they see on the micrograph is always correct. But, this may not be the case. The first paper in this series, discussed some of the issues related to signal generation in the SEM, instrument calibration, electron beam interactions and the need for physics-based modelling to accurately understand the actual image formation mechanisms. All these were summed together in a discussion of how these issues effect measurements made with the instrument. This second paper, discusses another major issue confronting the microscopist: specimen contamination. Over the years, NIST has done a great deal of research into the issue of sample contamination and its removal and elimination and some of this work is reviewed and discussed here.

In this paper, we present a simple and effective method to systematically derive an ensemble of Statistical Machine Translation (SMT) systems from one baseline linear SMT model for use in system combination. Each system in the resulting ensemble is based on a feature set derived from the features of the baseline model (typically a subset of it). We will discuss the principles to determine the feature sets for derived systems, and present in detail the system combination model used in our work. Evaluation is performed on the data sets for NIST 2004 and NIST 2005 Chinese-to-English SMT tasks. Experimental results show that our method can bring significant improvements to baseline systems with state-of-the-art performance.

Previous methods on improving translation quality by employing multiple SMT models usually carry out as a second-pass decision procedure on hypotheses from multiple systems using extra features instead of using features in existing models in more depth. In this paper, we propose translation model generalization (TMG), an approach that updates probability feature values for the translation model being used based on the model itself and a set of auxiliary models, aiming to alleviate the over-estimation problem and enhance translation quality in the first-pass decoding phase. We validate our approach for translation models based on auxiliary models built by two different ways. We also introduce novel probability variance features into the log-linear models for further improvements. We conclude our approach can be developed independently and integrated into current SMT pipeline directly. We demonstrate BLEU improvements on the NIST Chinese-to-English MT tasks for single-system decodings.

We describe the characterization of a group of NIST spectral irradiance lamps at longer distances and larger angles than are typically issued by NIST. The spectral irradiances from the FEL lamps were measured from 50 cm to 150 cm at 8 different distances using a cosine-corrected filter radiometer to determine if the lamps adhere to the inverse square law. Using the filter radiometer, the spatial uniformities of the FEL lamps were also mapped over a 20 cm square area at 135 cm, 143 cm and 151 cm. In the NIST gonio-spectroradiometer facility, selected lamps were also mapped for the angular dependences of the spectral irradiances at a distance of 123 cm using a spectrograph which measures from 300 nm to 1100 nm for comparisons to the filter radiometer measurements. Using these measurements, an uncertainty budget for the distance and the angular uniformity correction of the FEL lamps was developed.

The calibration of X-ray diagnostics is of paramount importance to the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). National Security Technologies LLC (NSTec) fills this need by providing a wide variety of calibration and diagnostic development services in support of the ongoing research efforts at NIF. The Xray source in the High Energy X-ray lab utilizes induced fluorescence in a variety of metal foils to produce a beam of characteristic X-rays ranging from 8 to 111 keV. Presented are the methods used for calibrating a High Purity Germanium detector, using NIST traceable radioactive sources, and compared against a silicon photodiode calibrated at Physikalisch Technische Bundesanstalt (PTB). A limited presentation of results from the recent calibration of the upgraded Filter Fluorescer X-ray Spectrometer is included.

Scales of spectral irradiance are disseminated by NIST using assignment of values to FEL lamp standards for defined conditions. These lamp standards can be used for absolute calibrations of irradiance radiometers, or more typically, be used in conjunction with a diffuse reflectance standard to establish a scale of spectral radiance and for subsequent absolute calibrations of radiance radiometers. The NIST FEL standards are valuable artifacts requiring special care. Many users optimize resources by in-house transfer of their primary standard to working standards. There are a number of sources of uncertainty in utilizing FEL lamps, e.g., lamp current, alignment, distance setting, instrument aperture size, drift, scattered light, and interpolation in the wavelength grid for the specified irradiance values. In this work, we validated the transfer activity by ITT of their primary, NIST-traceable FEL lamp standards. A portable irradiance bench that had kinematic mounts for an FEL lamp, on-axis baffle, and three different irradiance radiometers was built, tested, and deployed to ITT in Rochester, NY. We report the results of this comparison activity. An uncertainty budget was developed and it was found that the results agreed well within the combined uncertainties of 1.5% to 1.6% (k = 2).

Robert E.Parks from National Institute of Standards and Technology (NIST), America, first reported Random Ball Test (RBT), which is used to measure the absolute error of the reference surface of the interferometer. The basic course of this technology as followed: first, assemble the Random Ball in the confocal position of the interferometer system; then, measure the surface of the Random Ball and record the result; rotate the Random Ball to another position, meanwhile make sure that the Random Ball is in the confocal position all the time; In the new position, measure the surface of the Random Ball and record it again; repeat enough times as above, calculate the mean result of the measuring results, and this mean result is just the absolute error of the reference surface of the interferometer. Since 1998, other scholars have continued Robert E.Parks's research, and created a new type of the RBT. In this new technology, Random Ball is sustained by high pressure airflow, suspending in the air, and rotating around sphere center. This technology is called Dynamic Random Ball Test (DRBT), because the Random Ball is rotating during measurement. This article mainly reported the experiment study about the DRBT.

STARR II is a planned NIST facility for spectral measurements of specular reflectance and diffuse bidirectional reflectance distribution function (BRDF) that is the follow-on to the current NIST STARR (Spectral Tri-function Automated Reference Reflectometer) facility. STARR II will improve and expand on the measurement capabilities of STARR, increasing spectral coverage in the short-wave infrared spectral region and adding out-of-plane BRDF measurement capability. We present characteristics of a tunable light source constructed for STARR II, which is based upon a supercontinuum fiber laser and has a tuning range from 500 nm to 2450 nm, alongside those of the current lampbased system in STARR. We then discuss considerations for measuring BRDF using this source. The STARR II goniometer will employ an articulated robotic arm to center and orient the sample, and we calculate the transformations from orientation of the sample and receiver to incident and scattering angles for measurements of in-plane and out-ofplane BRDF. We also present, for the first time, an analytic expression for the correction of measured BRDF to true BRDF due to the finite illumination area and collection aperture, and to the effects of uniformity of illumination. Finally, we present exploratory BRDF measurements on a diffuse sample made using the tunable supercontinnum source.

We present work done to prepare two new near-infrared calibration sources for use on high-precision astrophysical spectrographs. Uranium-neon is an atomic calibration source, commercially available as a hollow-cathode lamp, with over 10 000 known emission lines between 0.85 and 4 μm. Four gas cells — containing C2H2, H13CN, 12CO, and 13CO, respectively—are available as National Institute of Standards and Technology (nist) Standard Reference Materials (SRMs), and provide narrow absorption lines between 1.5 and 1.65 μm. These calibration sources may prove useful for wavelength-calibrating the future near-infrared high-precision radial-velocity spectrometers, including the Calar Alto high-Resolution search for M dwarfs with Exo-earths with a Near-infrared Echelle Spectrograph (CARMENES),1 the SpectroPolarimetre InfraROUge (SPIRou)∗, and the Habitable-Zone Planet Finder (HPF).2

Changing atmospheric transmission accounts for the largest systematic errors limiting photometric measurement precision and accuracy for ground-based telescopes. While considerable resources have been devoted to correcting the effects of the atmosphere on image resolution, the effects on precision photometry have largely been ignored. To correct for the transmission of the atmosphere requires direct measurements of the wavelength-dependent transmission in the same direction and time that the supported photometric telescope is acquiring its data. We describe a multi-wavelength lidar, the Facility Lidar for Astronomical Measurement of Extinction (FLAME) that observes the stable upper stratosphere, and the Astronomical Extinction Spectrophotometer (AESoP), a spectrophotometer that creates and maintains NIST absolute standard stars. The combination of these two instruments enables high photometric precision of both the stellar spectra and atmospheric transmission. The throughput of both FLAME and AESoP are calibrated to NIST radiometric standards. This inexpensive and replicable instrument suite provides the lidar-determined monochromatic transmission of Earth’s atmosphere at visible and near-infrared wavelengths to better than 0.25% per airmass and the wavelength-dependent transparency to better than 1% uncertainty per minute. These atmospheric data are merged to create a metadata stream that allows throughput corrections from data acquired at the time of the scientific observations to be applied to broadband and spectrophotometric scientific data. This new technique replaces the classical use of nightly mean atmospheric extinction coefficients, which invoke a stationary and plane-parallel atmosphere and ultimately limit ground-based all-sky photometry to 1% - 2% precision.

NIST-calibrated detectors will be used by the ground-based 100mm diameter Astronomical Extinction Spectrophotometer (AESoP) to calibrate the spectral energy distributions of bright stars to sub-1% per 1nm spectral resolution element accuracy. AESoP will produce about a hundred spectroradiometrically calibrated stars for use by ground- and space-based sensors. This will require accurate and near-continuous NIST calibration of AESoP, an equatorially mounted objective spectrophotometer operating over the wavelength range 350nm – 1050nm using a CCD detector. To provide continuous NIST calibration of AESoP in the field a near-identical, removable 100mm diameter transfer standard telescope (CAL) is mounted physically parallel to AESoP. The CAL transfer standard is calibrated by NIST end-to-end, wavelength-by-wavelength at ~ 1nm spectral resolution. In the field, CAL is used in a near-field configuration to calibrate AESoP. Between AESoP science observations, AESoP and CAL simultaneously observe clear sub-apertures of a 400mm diameter calibration collimator. Monochromatic light measured simultaneously by AESoP and CAL is dispersed by the objective grating onto the AESoP pixels measuring the same wavelength of starlight, thus calibrating both wavelength and instrumental throughput, and simultaneously onto a unique low-noise CAL detector providing the required throughput measurement. System sensitivity variations are measured by vertically translating the AESoP/CAL pair so that CAL can observe the AESoP sub-aperture. Details of this system fundamental to the calibration of the spectral energy distributions of stars are discussed and its operation is described. System performance will be demonstrated, and a plan of action to extend these techniques firstly into the near infrared, then to fainter stars will be described.

Spectral responsivity calibrations of two different types of pyroelectric radiometers have been made in the infrared region up to 14 μm in power mode using three different calibration facilities at NIST. One pyroelectric radiometer is a temperature-controlled low noise-equivalent-power (NEP) single-element pyroelectric radiometer with an active area of 5 mm in diameter. The other radiometer is a prototype using the same type of pyroeletric detector with dome-input optics, which was designed to increase absorptance and to minimize spectral structures to obtain a constant spectral responsivity. Three calibration facilities at NIST were used to conduct direct and indirect responsivity calibrations tied to absolute scales in the infrared spectral regime. We report the calibration results for the single-element pyroelectric radiometer using a new Infrared Spectral Comparator Facility (IRSCF) for direct calibration. Also, a combined method using the Fourier Transform Infrared Spectrophotometry (FTIS) facility and single wavelength laser tie-points are described to calibrated standard detectors with an indirect approach. For the dome-input pyroelectric radiometer, the results obtained from another direct calibration method using a circular variable filter (CVF) spectrometer and the FTIS are also presented. The inter-comparison of different calibration methods enables us to improve the responsivity uncertainty performed by the different facilities. For both radiometers, consistent results of the spectral power responsivity have been obtained applying different methods from 1.5 μm to 14 μm with responsivity uncertainties between 1 % and 2 % (k = 2). Relevant characterization results, such as spatial uniformity, linearity, and angular dependence of responsivity, are shown. Validation of the spectral responsivity calibrations, uncertainty sources, and improvements for each method will also be discussed.

The National Institute of Standards and Technology (NIST) is developing a new generation of standards for calibration of CD-AFM tip width. These standards, known as single crystal critical dimension reference materials (SCCDRM) have features with near-vertical sidewalls. This is accomplished using preferential etching on (110) silicon-on-insulator (SOI) substrates. As such, these structures are particularly useful for CD-AFM tip width calibration. As part of a previous generation of SCCDRMs that was released to the Member Companies of SEMATECH, we were able to deliver structures with linewidths ranging from as low as 50 nm up to 240 nm. These typically had expanded uncertainties (k = 2) of between 1.5 nm and 2 nm. Subsequently, these chips were used as a traceable source of tip width calibration for CD-AFM by SEMATECH and several Member Companies. We are now working on a new generation of SCCDRMs with the goal of reducing linewidth expanded uncertainties, and we are using our new CD-AFM to support this development. The features are patterned using electron beam lithography with equipment available in the new nanofabrication facility within the Center for Nanoscale Science and Technology (CNST) at NIST. Intact features as small as 10 nm have been observed with line width roughness (LWR) sufficiently low to support 1 nm expanded uncertainties. We believe it will be possible to fabricate features as small as 5 nm, and we are now working to refine the fabrication process and to assess the limits of our approach.

Real-time monitoring of fracture critical steel bridges can potentially enhance inspection practices by tracking the behavior of the bridge. Significant advances have occurred in recent years on the development of robust hardware for field monitoring applications. These systems can monitor, process, and store data from a variety of sensors (e.g. strain gages, crack propagation gages etc.) to track changes in the behavior of the bridge. Thus, for a long-term monitoring system to be successful, the reliability of gages that are to be monitored for several years is very important. This paper focuses on the results of a research study focused on developing a wireless monitoring system with a useful life of more than 10 years. An important aspect of the study is to identify strain gages and installation procedures that result in long lives as well as characterizing the effect of temperature fluctuations and other environmental factors on the sensor drift and noise. In long-term monitoring applications, slight sensor drift and noise can build up over time to produce misleading results. Thus, a wide variety of gages that can be used to monitor bridges have been tested for over a year through environmental tests. The environmental tests were developed to determine the durability of the gages and their protective coatings (e.g. zinc-based spray, wax and silicon, etc.) against humidity, sun exposure and other environmental effects that are expected in long-term bridge monitoring applications. Moreover, fatigue tests were performed to determine the fatigue category of the weldable gages and to reveal any debonding issues of the bondable gages. This paper focuses on the results of laboratory tests on gage durability that were conducted as part of a research project sponsored by the National Institute of Standards and Technology (NIST).

Satellite instruments operating in the reflective solar wavelength region require accurate and precise determination of the Bidirectional Reflectance Factor (BRF) of laboratory-based diffusers used in their pre-flight and on-orbit radiometric calibrations. BRF measurements are required throughout the reflected-solar spectrum from the ultraviolet through the shortwave infrared. Spectralon diffusers are commonly used as a reflectance standard for bidirectional and hemispherical geometries. The Diffuser Calibration Laboratory (DCaL) at NASA's Goddard Space Flight Center is a secondary calibration facility with reflectance measurements traceable to those made by the Spectral Tri-function Automated Reference Reflectometer (STARR) facility at the National Institute of Standards and Technology (NIST). For more than two decades, the DCaL has provided numerous NASA projects with BRF data in the ultraviolet (UV), visible (VIS) and the Near InfraRed (NIR) spectral regions. Presented in this paper are measurements of BRF from 1475 nm to 1625 nm obtained using an indium gallium arsenide detector and a tunable coherent light source. The sample was a 50.8 mm (2 in) diameter, 99% white Spectralon target. The BRF results are discussed and compared to empirically generated data from a model based on NIST certified values of 6°directional-hemispherical spectral reflectance factors from 900 nm to 2500 nm. Employing a new NIST capability for measuring bidirectional reflectance using a cooled, extended InGaAs detector, BRF calibration measurements of the same sample were also made using NIST's STARR from 1475 nm to 1625 nm at an incident angle of 0° and at viewing angle of 45°. The total combined uncertainty for BRF in this ShortWave Infrared (SWIR) range is less than 1%. This measurement capability will evolve into a BRF calibration service in SWIR region in support of NASA remote sensing missions.

MODIS-Terra is one of the key sensors in the suite of remote sensing instruments in the Earth Observing System (EOS). MODIS on the Terra platform was launched into orbit in December of 1999 and has successfully completed eleven plus years of operation. MODIS has 36 spectral channels with wavelengths varying from 0.4 μm to 14.4 μm. The native spatial resolutions for the reflective channels are 2 bands at 0.25 km, 5 bands at 0.5 km and 29 bands at 1km. However, the MODIS L1B product allows the high spatial resolution bands to be aggregated into 1km resolution. All the thermal channels in MODIS (i.e. 3.75μm - 14.24μm) have a native spatial resolution of 1 km. Over the eleven plus years of mission lifetime, the sensor degradation has been carefully monitored using various On-Board Calibrators (OBC). In particular, the thermal channels are monitored using the on-board Black-Body (BB) which is traceable to NIST standards. MODIS also has a unique feature for calibration reference in terms of lunar irradiance. The lunar observations are scheduled for MODIS periodically (at least 9 observations in a calendar year). Based on the lunar observations, it was found that there was a possible signal leak for band 27 from its neighboring bands located on the Long-Wave Infrared (LWIR) focal plane. Further investigations revealed a possible leak from bands 28, 29 and 30. The magnitude of the leak was trended and correction coefficients were derived. In this paper, we demonstrate the across-band signal leak in MODIS band 27, its potential impact on the retrieved Brightness temperature (B.T.). Also, the paper explores a correction methodology to relieve the artifacts due to the across-band signal leak. Finally, the improvement in the band 27 image quality is quantified.

A machine-assisted analysis of traces from crime scenes might be possible with the advent of new high-resolution non-destructive contact-less acquisition techniques for latent fingerprints. This requires reliable techniques for the automatic extraction of fingerprint features from latent and exemplar fingerprints for matching purposes using pattern recognition approaches. Therefore, we evaluate the NIST Biometric Image Software for the feature extraction and verification of contact-lessly acquired latent fingerprints to determine potential error rates. Our exemplary test setup includes 30 latent fingerprints from 5 people in two test sets that are acquired from different surfaces using a chromatic white light sensor. The first test set includes 20 fingerprints on two different surfaces. It is used to determine the feature extraction performance. The second test set includes one latent fingerprint on 10 different surfaces and an exemplar fingerprint to determine the verification performance. This utilized sensing technique does not require a physical or chemical visibility enhancement of the fingerprint residue, thus the original trace remains unaltered for further investigations. No particular feature extraction and verification techniques have been applied to such data, yet. Hence, we see the need for appropriate algorithms that are suitable to support forensic investigations.

The Ocean Radiometer for Carbon Assessment (ORCA) is a new design for the next generation remote sensing of ocean biology and biogeochemistry. ORCA is configured to meet all the measurement requirements of the Decadal Survey Aerosol, Cloud, and Ecology (ACE), the Ocean Ecosystem (OES) radiometer and the Pro-ACE climate data continuity mission (PACE). Under the auspices of a 2007 grant from NASA Research Opportunity in Space and Earth Science (ROSES) and the Instrument Incubator Program (IIP), a team at the Goddard Space Flight Center (GSFC) has been working on a functional prototype with flight-like fore and aft optics and scan mechanisms. As part of the development efforts to bring ORCA closer to a flight configuration and in order to reduce cost, we have conducted component-level optical testing using standard spectrophotometers and system-level characterizations using non-flight commercial off-the-shelf (COTS) focal plane array detectors. Although these arrays would not be able to handle flight data rates, they are adequate for optical alignment and performance testing. The purpose of this presentation is to describe the results of this testing performed at GSFC and the National Institute of Standards and Technology (NIST) at the component and system level. Specifically, we show results for ORCA's spectral calibration ranging from the near UV, visible, and near-infrared spectral region.

The National Institute of Standards and Technology (NIST) has a multifaceted program in atomic force microscope (AFM) dimensional metrology. One component of this effort is a custom in-house metrology AFM, called the calibrated AFM (C-AFM). The NIST C-AFM has displacement metrology for all three axes traceable to the 633 nm wavelength of the iodine-stabilized He-Ne laser. A second major component of this program, and the focus of this paper, is the use of critical dimension atomic force microscopy (CD-AFM). CD-AFM is a commercially available AFM technology that uses flared tips and twodimensional surface sensing to scan the sidewalls of near-vertical or even reentrant features. Features of this sort are commonly encountered in semiconductor manufacturing and other nanotechnology industries. NIST has experience in the calibration and characterization of CD-AFM instruments and in the development of uncertainty budgets for typical measurands in semiconductor manufacturing metrology. A third generation CD-AFM was recently installed at NIST. The current performance of this instrument for pitch and height measurements appears to support our relative expanded uncertainty (k = 2) goals in the range of 1.0 × 10-3 down to 1.0 × 10-4.

The five axis goniospectrometer at the National Institute of Standards and Technology (NIST) measures the spectral reflectance of colored samples over a wide range of illumination and viewing angles. This capability is important for the colorimetric characterization of complex materials, such as gonioapparent coatings or retroreflective surfaces. To improve the efficiency of the goniometer, a broad-band source with a matrix-based stray-light corrected CCD based spectrometer was implemented. This new configuration offers a significant reduction in the measurement time allowing for the complete characterization of the goniodistribution of complex materials. Shorter measurement time reduces the load on the precise mechanical assembly, to ensure high angular accuracy over time. Special care was taken to extend the effective dynamic range of measured intensities in the multichannel detection mode to the values of 10 6 - 10 7 needed for the characterization of colored samples. The expanded uncertainty of the measured Bidirectional Reflectance Distribution Function (BRDF) for this new setup is about 0.5 % ( k = 2 ) which is comparable to the uncertainty levels of the instrument operating with monochromatic illumination and a silicon photodiode. To validate the new system configuration, the measured BRDF or spectral reflectance factors (R) of test samples were compared with different instruments and we found an agreement of about 0.5 %.

Before being used in an extreme-ultraviolet (EUV) scanner, photoresists must be qualified to ensure that they will not excessively contaminate the scanner optics or other parts of the vacuum environment of the scanner. At the National Institute of Standards and Technology we have designed and constructed a high-throughput beamline on the Synchrotron Ultraviolet Radiation Facility (SURF III) in order to provide data on the contamination potential of the outgas products of a candidate resist by simultaneously irradiating a witness substrate and a nearby resist-coated wafer with EUV radiation, the so called witness sample test that is currently the resist qualification method required by ASML. We will present results from four sample resists that were subjected to the test. Although the witness-sample test based on irradiating the resist with EUV radiation at 13.5 nm most closely reproduces conditions in a scanner, the limited availability of suitable EUV sources to conduct such tests has led to development of an alternative method which uses e-beam irradiation in place of EUV radiation. We will also present the results of a comparison of these two methods.

There are numerous medical conditions which may benefit from hyperspectral imaging. The imagers used for these conditions will need to have the performance validated to ensure consistency, gain acceptance and clear regulatory hurdles. NIST has been developing a Digital Light Processing (DLP)-based Hyperspectral Image Projector (HIP) for providing scenes with full spectral content in order to evaluate multispectral and hyperspectral imagers. In order for the scene to be projected, a dimensionality reduction is performed in order to project spectra efficiently. The number of eigenspectra needed to best represent a scene is an important part in the recombining of the image. This paper studies the spectral diversity between different medical scenes collected by a DLP based hyperspectral imager. Knowledge gained from this study will help guide the methods used for hyperspectral image projection of medical scenes in the future.

Currently all LMS IPRO pattern placement metrology tools are calibrated using a 1D length standard provided by a national standards institute (e.g. NIST or PTB), however there are no 2-D standards available with an uncertainty matching the requirements of mask manufacturing for the 22nm HP node and beyond. Therefore, the 2D stage coordinate system of the LMS IPRO systems is calibrated using KLA Tencor's proprietary combined correction technique. With introduction of the LMS IPRO4 into high volume mask production at the AMTC, AMTC and KLA-Tencor MIE have demonstrated the capability to match IPRO3 and IPRO4 grids within 1.2 nm uncertainty [1]. Using the Golden Tool approach, we achieved a significant improvement in pattern placement measurement capability of previous generation measurement tools of up to 30%. This in turn leads to improved pattern placement metrology fleet capability and extended useful lifetime of capital equipment. The use of multiple high end registration measurement tools enables the creation of a 2D coordinate system standard, which could be used for improved fleet matching and would help improve the capability of older generation pattern placement metrology tools by matching to this standard. Within this paper Golden Tool and Round Robin worldwide fleet matching approaches are compared and discussed.

NIST has introduced a new standard for dimensional metrology and the calibration of the scanning electron microscope (SEM) scale identifi ed as Reference Material (RM) 8820. RM 8820 was primarily intended to be used for calibrating the X and Y scale (or magnifi cation) in SEMs but, can be used for an many other purposes. Essentially, all laboratory microscopes can be calibrated to this same artifact. The NIST pattern is only one part of a very large array of test structures that were designed for various dimensional metrology purposes useful to semiconductor production technologies. These and other purposes, discussed in the presentation, RM 8820 can also be used on/in any other type of microscope, such as optical and scanning probe microscopes and for scatterometry measurements.

ACCESS, Absolute Color Calibration Experiment for Standard Stars, is a series of rocket-borne sub-orbital missions and ground-based experiments designed to enable improvements in the precision of the astrophysical flux scale through the transfer of absolute laboratory detector standards from the National Institute of Standards and Technology (NIST) to a network of stellar standards with a calibration accuracy of 1% and a spectral resolving power of 500 across the 0.35.1.7μm bandpass. Establishing improved spectrophotometric standards is important for a broad range of missions and is relevant to many astrophysical problems. Systematic errors associated with problems such as dark energy now compete with the statistical errors and thus limit our ability to answer fundamental questions in astrophysics. The ACCESS design, calibration strategy, and an updated preliminary performance estimate are discussed.

The Low-Background Infrared (LBIR) facility at NIST has recently completed construction of an infrared transfer radiometer with an integrated cryogenic Fourier transform spectrometer (Cryo-FTS). This mobile system can be deployed to customer sites for broadband and spectral calibrations of space chambers and low-background HWIL testbeds. The Missile Defense Transfer Radiometer (MDXR) has many of the capabilities of a complete IR calibration facility and will replace our existing filter-based transfer radiometer (BXR) as the NIST standard detector deployed to MDA facilities. The MDXR features numerous improvements over the BXR, including: a cryogenic Fourier transform spectrometer, an on-board absolute cryogenic radiometer (ACR), an internal blackbody reference, and an integrated collimator. The Cryo-FTS can be used to measure high resolution spectra from 4 to 20 micrometers, using a Si:As blocked-impurity-band (BIB) detector. The on-board ACR can be used for self-calibration of the MDXR BIB as well as for absolute measurements of infrared sources. A set of filter wheels and a rotating polarizer within the MDXR allow for filter-based and polarization-sensitive measurements. The optical design of the MDXR makes both radiance and irradiance measurements possible and enables calibration of both divergent and collimated sources. Details of the various MDXR components will be presented as well as initial testing data on their performance.

Active learning methods have gained popularity to reduce human effort in annotating examples in order to train a classifier. When faced with large amounts of data, the active learning algorithm automatically selects appropriate data samples that are most relevant to train the classifier. Typical active learning approaches select one data instance (one face image, for example) in one iteration of the algorithm, and the classifier is trained with the selected data instances, one-by-one. Instead, there have been very recent efforts in active learning to select a batch of examples for labeling at each instant rather than selecting a single example and updating the hypothesis. In this work, a novel batch mode active learning scheme based on numerical optimization of an appropriate function has been applied to the biometric recognition problem. In problems such as face recognition, real-world data is often generated in batches, such as frames of video in a capture session. In such scenarios, selecting the most appropriate data instances from these batches (which usually have a high redundancy) to train a classifier is a significant challenge. In this work, the instance selection is formulated as a mathematical optimization problem and the framework is extended to handle learning from multiple sources of information. The results obtained on the widely used NIST Multiple Biometric Grand Challenge (MBGC) and VidTIMIT biometric datasets corroborate the potential of this method in being used for real-world biometric recognition problems, when there are large amounts of data.

A new multipurpose instrument calibration standard has been released by NIST. This standard was developed to be used primarily for X and Y scale (or magnification) calibrations of scanning electron microscopes from less than 10 times magnification to more than 300 000 times magnifi cation, i.e., from about 10 mm to smaller than 300 nm range instrument field of view (FOV). This standard is identifi ed as RM 8820. This is a very versatile standard, and it can also be used for calibration and testing of other type of microscopes, such as optical and scanning probe microscopes. Beyond scale calibration, RM 8820 can be used for a number of other applications, some of which will be described in this publication.