Standard Blackbody Source Research Articles

Spectroscopic measurement of the two-dimensional flame temperature based on a perovskite single photodetector.

Existing non-contact flame temperature measuring methods depend on complex, bulky and expensive optical instruments, which make it difficult for portable applications and high-density distributed networking monitoring. Here, we demonstrate a flame temperature imaging method based on a perovskite single photodetector. High-quality perovskite film epitaxy grows on the SiO2/Si substrate to fabricate the photodetector. Duo to the Si/MAPbBr3 heterojunction, the light detection wavelength is extended from 400 nm to 900 nm. Then, a perovskite single photodetector spectrometer has been developed using the deep-learning method for spectroscopic measurement of flame temperature. In the temperature test experiment, the spectral line of doping element K+ has been selected to measure the flame temperature. The photoresponsivity function of the wavelength was learned based on a commercial standard blackbody source. The spectral line of element K+ has been reconstructed using the photocurrents matrix by the regression solving photoresponsivity function. As a validation experiment, the "NUC" pattern is realized by scanning the perovskite single-pixel photodetector. Finally, the flame temperature of adulterated element K+ has been imaged with the error of 5%. It provides a way to develop high precision, portable, low-cost flame temperature imaging technology.

Perovskite single-detector visible-light spectrometer.

We demonstrate a perovskite single-phototransistor visible-light spectrometer based on a deep-learning method. The size of the spectrometer is set to the scale of the phototransistor. A photoresponsivity matrix for the deep-learning system is learned from the characteristic parameters of the visible-light wavelength, gate voltage, and power densities of a commercial standard blackbody source. Unknown spectra are reconstructed using the corresponding photocurrent vectors. As a confirmatory experiment, a 532-nm laser and multipeak broadband spectrum are successfully reconstructed using our perovskite single-phototransistor spectrometer. The resolution is improved to 1 nm by increasing the number of sampling points from 80 to 400. In addition, a way to further improve the resolution is provided by increasing the number of sampling points, characteristic parameters, and training datasets. Furthermore, artificial intelligence technology may open pathways for on-chip visible-light spectroscopy.

A temperature-controlled mid-wave infrared polarization radiation source with adjustable degree of linear polarization

This paper proposes a temperature-controlled mid-wave infrared polarization radiation source with adjustable degree of linear polarization (DoLP), referred to as TMPSD, which will be useful for the polarization performance measurements of the thermal polarization imaging systems. The main parts of the TMPSD are a standard blackbody source, a variable temperature cell holder and a mid-wave infrared polarizer placed in it. The experimental results show that when the temperature range of the blackbody source changes between 20 °C and 100 °C, and that of the polarizer between −120 °C and 20 °C, the DoLP of the radiation emitted from the TMPSD is 0.2683–0.9072 in the 3.0–5.2 μm bandwidth. The TMPSD exhibiting the large dynamic range and high accuracy can be readily adjusted. It is expected that the proposed TMPSD will effectively improve the quantitative accuracy of infrared polarization imaging systems during performance calibration and testing of mid-wave infrared polarization imaging systems.

VIS-NIR multispectral synchronous imaging pyrometer for high-temperature measurements.

A visible-infrared multispectral synchronous imaging pyrometer was developed for simultaneous, multispectral, two-dimensional high temperature measurements. The multispectral image pyrometer uses prism separation construction in the spectrum range of 650-950 nm and multi-sensor fusion of three CCD sensors for high-temperature measurements. The pyrometer had 650-750 nm, 750-850 nm, and 850-950 nm channels all with the same optical path. The wavelength choice for each channel is flexible with three center wavelengths (700 nm, 810 nm, and 920 nm) with a full width at half maximum of the spectrum of 3 nm used here. The three image sensors were precisely aligned to avoid spectrum artifacts by micro-mechanical adjustments of the sensors relative to each other to position them within a quarter pixel of each other. The pyrometer was calibrated with the standard blackbody source, and the temperature measurement uncertainty was within 0.21 °C-0.99 °C in the temperatures of 600 °C-1800 °C for the blackbody measurements. The pyrometer was then used to measure the leading edge temperatures of a ceramics model exposed to high-enthalpy plasma aerodynamic heating environment to verify the system applicability. The measured temperature ranges are 701-991 °C, 701-1134 °C, and 701-834 °C at the heating transient, steady state, and cooling transient times. A significant temperature gradient (170 °C/mm) was observed away from the leading edge facing the plasma jet during the steady state heating time. The temperature non-uniformity on the surface occurs during the entire aerodynamic heating process. However, the temperature distribution becomes more uniform after the heater is shut down and the experimental model is naturally cooled. This result shows that the multispectral simultaneous image measurement mode provides a wider temperature range for one imaging measurement of high spatial temperature gradients in transient applications.

Binary coded identification of industrial chemical vapors with an optofluidic nose.

An artificial nose system for the recognition and classification of gas-phase analytes and its application in identifying common industrial gases is reported. The sensing mechanism of the device comprises the measurement of infrared absorption of volatile analytes inside the hollow cores of optofluidic Bragg fibers. An array of six fibers is used, where each fiber targets a different region of the mid-infrared in the range of 2-14μm with transmission bandwidths of about 1-3μm. The quenching in the transmission of each fiber due to the presence of analyte molecules in the hollow core is measured separately and the cross response of the array allows the identification of virtually any volatile organic compound (VOC). The device was used for the identification of seven industrial VOC vapors with high selectivity using a standard blackbody source and an infrared detector. The array response is registered as a unique six digit binary code for each analyte by assigning a threshold value to the fiber transmissions. The developed prototype is a comprehensive and versatile artificial nose that is applicable to a wide range of analytes.

Research on radiometric calibration for super wide-angle staring infrared imaging system

To perform radiometric calibration on super wide-angle staring infrared imaging system, the calibration experiment is carried out by using a standard blackbody source with a plate shape in laboratory, and the error analysis and data inversion are made based on the calibration results. Firstly, through analyzing the influencing factors including optical system, detector and signal processing circuit, the optical response model is established. Then, the radiometric calibration experiment is developed in the darkroom environment, and the error analysis is done from six aspects, which are the temperature and radiation instability of the black body, goniometer accuracy, angular resolution, the instability of detector output, data fitting error. Finally, according to the calibration results and the imaging characteristics of short-range airplane in the system, the infrared radiation intensity of aircraft target is calculated. The radiometric calibration and data inversion will benefit obtaining the target radiation characteristic during the system application, and can provide data reference for target detection, recognition, classification, so on.

Calculations of the average normal effective emissivity for nonaxisymmetric cavities using the modified finite volume method

The average normal effective emissivity is widely used for calibration since it depends only on the intrinsic cavity characteristics; thus, it is an important parameter for blackbody designs and evaluations. Nonaxisymmetric cavities are widely used as standard blackbody sources and cryogenic solar absolute radiometers. The finite volume method is modified by adding a black-hole cylindrical extension to extend the integrated effective emissivity computations to the much more complex computations of average normal effective emissivities for nonaxisymmetric cavities. The calculated results using the modified finite volume method have an average relative difference of 0.085% from the Monte Carlo method, which is the only reported method for average normal effective emissivities of nonaxisymmetric cavities. The results show that this method can be used effectively for calculating the average normal effective emissivities of cavities with complex geometries.

Integrated ef fective emissivity computation for non-isothermal non-axisymmetric cavities

Non-axisymmetric cavities are widely used as standard blackbody sources for radiation thermometry. The integrated effective emissivity is central to the blackbody design. Integrated effective emissivities are numerically calculated for non-isothermal, non-axisymmetric cavities. The average relative deviation is 0.087% when compared with Monte-Carlo results, indicating that this method can accurately calculate the integrated effective emissivities for non-isothermal, non-axisymmetric cavities. The effects of the wavelength, temperature uniformity, and bottom inclination angle are then analyzed.

Comparison Measurements of Infrared Ear Thermometers Against Three Types of Blackbody Sources

Body temperature is a basic vital sign of the human body, and the use of infrared ear thermometers for medical diagnosis and health management on human bodies has been widespread nowadays. To gain credibility and confidence in the usage of IR ear thermometers, a standard blackbody source (BBS) with a calibration traceable to ITS-90 is necessitated. Three types of cavity-shaped blackbodies (designated BBC-A, BBC-E, and BBC-J) vertically immersed in a temperature-controlled stirred water bath were developed at the Center for Measurement Standards (CMS) as standard BBSs to calibrate and verify 14 commercial IR ear thermometers produced by six manufacturers. The basic structure of each cavity was designed based on the informative examples recommended in ASTM E-1965, EN 12470-5, and JIS T 4207 standards. The temperature of the blackbody cavity shall be represented by the water temperature near the bottom of the cavity that is measured using an immersed platinum resistance thermometer (PRT) for which the calibration is traceable to our national standard and with an uncertainty no greater than 0.03 °C (k = 2). The water bath was evaluated using the PRT to be stable within ±3.5 mK over 1 h and uniform within ±1.1 mK. Three types of BBSs were compared and analyzed utilizing two IR ear thermometers of 0.01 °C resolution as well as the statistical technique of analysis of variance (ANOVA). On the contrary, IR ear thermometers were tested and verified against three BBSs at three blackbody temperatures of 35.5 °C, 37 °C, and 41 °C. The analysis results of ANOVA showed that there is no significant temperature difference among three different structured blackbodies, and the average measured radiance temperature of three BBSs at 35.5 °C, 37 °C, and 41 °C were within 0.026 °C, 0.024 °C, and 0.027 °C of each other. Three among fourteen IR ear thermometers tested were outside of the 0.2 °C MPE (maximum permissible error) recommended by ASTM E-1965, EN 12470-5, or JIS T 4207 standards while BBC-A and BBC-E were used; however, four were outside of MPE requirement when BBC-J was used.

Improved spatial resolution for reflection mode infrared microscopy

Standard commercial infrared microscopes operating in reflection mode use a mirror to direct the reflected light from the sample to the detector. This mirror blocks about half of the incident light, however, and thus degrades the spatial resolution by reducing the numerical aperture of the objective. Here, we replace the mirror with a 50% beamsplitter to allow full illumination of the objective and retain a way to direct the reflected light to the detector. The improved spatial resolution is demonstrated using two different microscopes capable of diffraction-limited resolution: the first microscope is coupled to a synchrotron source and utilizes a single point detector, whereas the second microscope has a standard blackbody source and uses a focal plane array detector.

High-Sensitivity InAsSb Photoconductors with a Response Wavelength Range of 2–9 µm Operated at Room Temperature

InAsSb immersion photoconductors with a response wavelength range of 2–9 µm operated at room temperature were reported. The detectors are based on InAsSb single crystals grown on InAs substrates by melt epitaxy (ME). Van der Pauw measurements showed that the 300 K electron mobilities of InAsSb materials are higher than 5×104 cm2 V-1 s-1 with carrier densities of (1–3)×1016 cm-3. The photoconductors were measured using a standard blackbody source at a temperature of 500 K and a modulation frequency of 800 Hz under an applied bias current of 10 mA. At 293 K, the blackbody detectivity Dbb* (500 K, 800) reaches (2–6)×108 cm Hz1/2 W-1, indicating the high sensitivity of the detectors and their potential detection applications.

Duel-Band Infared Imagery of an Atlas 5 Launch Vehicle in Flight

Imagery acquired with a quantum-well infrared photodetector dual-band infrared focal plane array of the inaugural launch of the Atlas 5 launch vehicle is presented. The focal plane array was developed under the U.S. Army Research Laboratory's Advanced Sensors Federated Laboratory program and used a read-out integrated circuit produced under the Air Force Research Laboratory's Advanced Multi-Quantum Well Technology program. The detectors are able to sense light in both the 3-5- and 8-12-μm atmospheric transmission windows such that the resulting single-band images are pixel registered and simultaneous. The focal plane array was installed in a camera system that used a closed-cycle cooler to operate at 60 K. The camera was placed at the prime focus of an all-reflective telescope on a computer-controlled tracking mount at the Innovative Sensor Technology Evaluation Facility at the Kennedy Space Center. The launch was observed from a distance of 15 km from the pad. The dual-band camera system was calibrated using standard blackbody sources. The launch vehicle was observed from about 30 s after launch until approximately 4 min after launch. This corresponded to ranges between 15 km and more than 300 km and altitudes from just over 1 km to more than 100 km

Calibrated Thermal Microscopy of the Tool–Chip Interface in Machining

This paper presents the results of calibrated, microscopic measurement of the temperature fields at the tool–chip interface during the steady‐state, orthogonal machining of AISI 1045 steel. The measurement system consists of an infrared imaging microscope with a 0.5 mm square target area, and a spatial resolution of less than 5 µm. The system is based on an InSb 128 × 128 focal plane array with an all‐reflective microscope objective. The microscope is calibrated using a standard blackbody source from NIST. The emissivity of the machined material is determined from the infrared reflectivity measurements. Thermal images of steady state machining are measured on a diamond‐turning class lathe for a range of machining parameters. The measurements are analyzed by two methods: 1) energy flux calculations made directly from the thermal images using a control–volume approach; and 2) a simplified finite‐difference simulation. The standard uncertainty of the temperature measurements is ± 52°C at 800°C.

A simple secondary standard radiation thermometer for use in industrial standards laboratories

A design of radiation thermometer is described which has been developed to transfer the calibration from fixed-point primary standard black-body sources to industrial black-body furnaces. Accurate interpolation can be achieved by a simple four-term polynomial. The thermometers are sufficiently stable to act as secondary standards in an industrial laboratory, with an uncertainty of better than ±0.5 K over the range 400–1250°C. The operation, evaluation and calibration of three thermometers are discussed.