Calibration System Research Articles

Development of radon detectors calibration system in Cameroon

ObjectiveTo develop a radon detectors calibration system at the Research Centre for Nuclear Science and Technology (CRSTN) of the Institute of Geological and Mining Research (IRGM) in Cameroon. MethodsA transparent box named radon chamber, a certified radon source, and a reference device have been provided to Cameroon by the International Atomic Energy Agency (IAEA) within the framework of a technical cooperation project. Depending on what radon levels are expected, two different configurations (Hookup I and Hookup II) of the system are adopted. Hookup I is a closed loop, and Hookup II is an open loop that samples fresh air. ResultsThe operation of the system generates a radon concentration of up to ∼ 30,000 Bq/m3 when applied the Hookup I and of up to ∼1,000 Bq/m3 using the Hookup II configuration. For the calibration of the detectors for environmental radon monitoring, a stabilized concentration of ∼1,000 Bq/m3 is enough. Furthermore, temperature, relative humidity, and pressure, in the reference instrument ranged from 23 to 40°C, 32 to 72%, and 929 to 936 mBar, respectively. Inside the radon chamber, temperature, relative humidity, and pressure are similar to the laboratory’s condition. ConclusionThe present calibration system will be useful for the calibration of radon detectors. The system can also be used for various purposes such as research activities on radon, education on radon detection, radon measurement, radon mitigation, radon mapping, protection against radon, and research in the African region.

An X-ray fluorescence experimental method for photon-counting detector in computed tomography system

The X-ray fluorescence (XRF) spectrum of specific elements can be utilized in energy calibration, energy resolution measurement, and analysis of energy response functions for photon-counting detectors (PCDs). The applications can be beneficial for PCD threshold accuracy, performance verification, and optimizing image quality. In previous literature, the experimental configuration for the XRF spectrum typically employed a vertical configuration to avoid the influence of the primary X-ray beam. However, such an experimental configuration is constrained by the fixed position of the X-ray source and detector in the computed tomography (CT) system. Hence, the purpose of this study is to investigate a horizontal configuration for XRF measurements and compare the differences in XRF spectrum with vertical configuration. The results indicate that the spectral characteristics of the horizontal and vertical configurations are similar, suggesting that the horizontal configuration could be applied for energy calibration and spectral analysis in PCD-CT systems.

Robust calibration of surround-view camera systems with Planar-Eccentric Constraint: A novel Apriltag approach

This research tackles calibrating surround view camera systems for automated driving, where traditional methods require extensive manual measurements and precise conditions. We introduce a novel automatic calibration method that ensures portability and accuracy using only custom-designed calibration boards placed in the cameras’ common view. To address visual interference from extraneous objects, we design a unique board with AprilTag 2D codes, offering clear advantages over traditional checkerboards. Additionally, we’ve developed an Adaptive Angle Projection to counteract fisheye lens distortions. We also introduce a hierarchical pose optimization strategy that transitions from local to global, incorporating a “Planar-Eccentric constraint” to leverage the calibration board’s geometric positioning. Our method achieved 4.01 cm measurement error, with 0.075°angle error and 1.18 cm translation error. Our method’s efficacy and robustness were confirmed through extensive testing on an experimental vehicle and simulation dataset, proving its superiority in achieving precise calibration and measurement with minimal manual input.

Design and Characterisation of a Low-Photon Flux UV-Radiance Standard for the Calibration of Radioluminescence Detection Systems

Abstract For the calibration of the radioluminescence detection systems developed within 19ENV02 RemoteALPHA EMPIR project, two purely optical radiation-based devices, which accurately simulate the radioluminescence induced in air nitrogen by an alpha-particle emitted from a planar radionuclide-based sample, were designed, manufactured, and characterized. The variable low-photon flux radiance sources are based on a combination of two integrating spheres and LEDs as UV-A and UV-C radiation sources. The calibrated maximum integrated photon radiances are 7.5·1011 s−1·m−2·sr−1 for the UV-A (CWL = 337 nm, FWHM = 10 nm) and 3.0·1010 s−1·m−2·sr−1 for the UV-C (CWL = 260 nm, FWHM = 20 nm) spectral range with relative standard uncertainties (k=1) from 5 % (UV-A) to 8 % (UV-C).

Optical-atomic system integration and calibration: Pumping from 1 atm to 1 × 10-11 Torr in 24 h.

Ultracold atoms exquisitely controlled by lasers are the quantum foundation, particularly for sensing, timekeeping, and computing, of state-of-the-art quantum science and technology. However, the laboratory-scale infrastructure for such optical-atomic quantum apparatus rarely translates into commercial applications. A promising solution is miniaturizing the optical layouts onto a chip-scale device integrated with cold atoms inside a compact ultra-high vacuum (UHV) chamber. For prototyping purposes, however, rapidly loading or exchanging test photonic devices into a UHV chamber is limited by the evacuation time from atmospheric pressures to the optimal pressures for ultracold atoms of 1 × 10-11 Torr, a process that typically takes weeks or months without cryogenics. Here, we present a loadlock apparatus and loading procedure capable of venting, exchanging, and evacuating back to <1×10-11 Torr in under 24h. Our system allows for rapid testing and benchmarking of various photonic devices with ultracold atoms.

C-type two-thermocouple sensor design between 1000 and 1700 °C.

At the present stage of transient ultra-high-temperature energy release of boron-containing warm-pressure explosives, single thermocouples are often used for multi-point measurements in the process of their temperature field changes, and the results of their temperature field reconstruction are not satisfactory due to the limited consistency of the thermocouples. Aiming at the above-mentioned problems, a C-type two-thermocouple suitable for transient temperature measurement in high-temperature environments is designed; the system characterization of the two-thermocouple is carried out by using the blind system identification method of the inter-relationships; the identification process is evaluated by a new cost function; and the optimal solution on the new cost function is realized by using the gradient descent method. The temperature reconstruction of the two-thermocouple output excited by the simulated heat source is carried out by using the auto-regressive with extra inputs model, and the feasibility of the reconstruction results is verified. In the experimental part, a thermocouple dynamic characteristic calibration system based on a high-temperature furnace is constructed and experimental validation is carried out in the high-temperature furnace to compare the effects of different exposure lengths and different wire diameters on the output of the two-thermocouple, and as a result, the outputs are corrected and analyzed. The results show that two-thermocouple methods with different combinations of wire diameters are better for temperature measurement, with a reconstructed root mean squared error of 0.0162 and a goodness of fit of 89.13%.

Current Progress of EUV Spectral Responsivity Calibration for EUV Lithography at CMS/ITRI

Abstract To support the development of advanced EUV lithography for the semiconductor industry in Taiwan, a calibration system for photodiodes’ spectral responsivity was established. The current system utilizes the synchrotron radiation light source and the method is traceable to PTB, Germany. The wavelength range is from 10 nm to 15 nm, including the most often used 13.5 nm. Several techniques were studied to compensate for light source fluctuation and to reduce the measurement uncertainty. The relative expanded uncertainty of the spectral responsivity calibration at 13.5 nm is 4.6 % (k=2). A wafer-type EUV radiant power meter designed to be used in EUV lithography chambers is being developed. Our goal is to develop simple and reliable methods for on-site EUV optical power measurement and dose estimation.

Research on the Positioning and Tracking Technology of Surgical Instruments Based on Laser Localization

Abstract Addressing the complexities and low accuracy of traditional surgical instrument positioning processes, a low-cost, high-precision surgical instrument tracking and positioning strategy is proposed. By integrating the VR laser positioning system, Lighthouse, with oral medicine, the positioning process and principles of the system are elucidated. Based on the initial system calibration, static positioning accuracy tests were conducted, and the positioning and tracking of the surgical instrument endpoints were achieved through the least squares method. Experimental results demonstrate that both static and dynamic positioning errors of the system are less than 0.3mm, meeting the requirements of oral surgical navigation.

Research on Calibration device of gas leakage alarm system and uncertainty analysis

Abstract This paper studies the calibration device and method of the gas leakage alarm system, and evaluates the uncertainty of the measurement results. Firstly, it analyzes the important components, parameters, and working principles of the gas leakage alarm system. Then, it designs a set of inhalation-type gas leakage alarm system calibration devices to test the indication error, repeatability, and response time of the alarm system, and evaluates the uncertainty of the calibration device. The study concludes that the relative expanded measurement uncertainty of the device calibrating the alarm system is 2.6%, which meets the accuracy requirements of national standards for calibration devices. The main factors affecting the measurement results are the resolution and repeatability of the alarm system being tested. By improving the performance of the alarm system sensor, the measurement results of the alarm system can be made closer to the true value, reducing misjudgment and improving the accuracy of the system. And during calibration, the measurement capability of the device can be enhanced by using higher grade gas standard substances.

Monte Carlo modeling and simulation of a new 3D printed phantom for WBC calibration with ballistic gel as a tissue substitute

Whole-body counter (WBC) systems are used for in vivo monitoring in occupational internal dosimetry, typically calibrated using physical anthropomorphic phantoms. Our research group previously 3D-printed the Reference Female Phantom for Internal Dosimetry (RFPID) without internal organs specifically designed for WBC calibration. The RFPID and it is intended to fill it homogenously with ballistic gel, which is commonly used as a tissue equivalent in ballistic studies. However, comprehensive characterization of its physicochemical properties and radiological behavior as a tissue surrogate for dosimetry is limited. This study aims to evaluate the suitability of ballistic gel as a tissue substitute for physical phantoms in WBC system calibration and to analyze the RFPID as a model for WBC calibration. Ballistic gel tests determined its density and attenuation coefficients, comparing it to muscle, water, and PMMA. The RFPID was modeled and simulated using MCNP6.2 code and placed in an in vivo monitoring system using an 8”x4” NaI(Tl) scintillator detector previously validated. The simulations were repeated with the RCP_AF of ICRP-110. Results indicate that ballistic gel has a density approximately 6% different from muscle and shows similar linear attenuation coefficients to muscle at intermediate and high energy levels (186 to 2200 keV). Simulations revealed a disparity of less than 9% in counting efficiency between RFPID and RCP_AF for energies from 100 to 3000 keV, confirming the phantom's suitability for WBC calibration and ballistic gel's viability as a tissue surrogate in internal dosimetry.

Development of novel interferometric system for short and long gauge block calibration

Abstract This paper presents the development of a novel multiwavelength Twyman–Green interferometer for gauge block (GB) calibration. In this work, a novel gauge block interferometer (GBI) for both short- and long-gauge block calibration at the SASO-NMCC was designed, built, tested, and described. The interferometer features an optomechanical modulation-based proprietary evaluation system, and the final length value was determined by applying Edlén’s equation to the refractive index of air. The developed interferometric system comprises two setups: one for short GB calibration, and the other for long GB calibration. The first short (GBI) setup utilizes two stabilized lasers, green and red, in vertical-mode operation. Another long GBI utilizes three stabilized lasers in the horizontal mode of operation. The primary characteristics of the interferometric system are explained. An uncertainty analysis with a careful study of the main components, such as wavelength standards, fringe fraction, temperature corrections, refractive index correction, obliquity correction, phase correction, block geometry correction, wavefront correction, and wringing correction, is presented. With interferometry, measurement method (ISO 3650 and ASME B89.1), using our described highly-precision horizontal mode system (GBI), we could achieve uncertainty level of ‘Q[49;0,28 l]nm l (mm)’ (k = 2) in the measurement range ‘125–1000 (mm)’. For the other system(GBI) for short gauge blocks, the associated uncertainty is ‘Q[30;0,27 l]nm l(mm)’ (k = 2) in the range of ‘0.5–100 (mm)’.

An open-source data storage and visualization platform for collaborative qubit control.

Developing collaborative research platforms for quantum bit control is crucial for driving innovation in the field, as they enable the exchange of ideas, data, and implementation to achieve more impactful outcomes. Furthermore, considering the high costs associated with quantum experimental setups, collaborative environments are vital for maximizing resource utilization efficiently. However, the lack of dedicated data management platforms presents a significant obstacle to progress, highlighting the necessity for essential assistive tools tailored for this purpose. Current qubit control systems are unable to handle complicated management of extensive calibration data and do not support effectively visualizing intricate quantum experiment outcomes. In this paper, we introduce Qubit Control Storage and Visualization (QubiCSV), a platform specifically designed to meet the demands of quantum computing research, focusing on the storage and analysis of calibration and characterization data in qubit control systems. As an open-source tool, QubiCSV facilitates efficient data management of quantum computing, providing data versioning capabilities for data storage and allowing researchers and programmers to interact with qubits in real time. The insightful visualization are developed to interpret complex quantum experiments and optimize qubit performance. QubiCSV not only streamlines the handling of qubit control system data but also improves the user experience with intuitive visualization features, making it a valuable asset for researchers in the quantum computing domain.

Hall thruster model improvement by multidisciplinary uncertainty quantification

We study the analysis and refinement of a predictive engineering model for enabling rapid prediction of Hall thruster system performance across a range of operating and environmental conditions and epistemic and aleatoric uncertainties. In particular, we describe an approach by which experimentally-observed facility effects are assimilated into the model, with a specific focus on facility background pressure. We propose a multifidelity, multidisciplinary approach for Bayesian calibration of an integrated system comprised of a set of component models. Furthermore, we perform uncertainty quantification over the calibrated model to assess the effects of epistemic and aleatoric uncertainty. This approach is realized on a coupled system of cathode, thruster, and plume models that predicts global quantities of interest (QoIs) such as thrust, efficiency, and discharge current as a function of operating conditions such as discharge voltage, mass flow rate, and background chamber pressure. As part of the calibration and prediction, we propose a number of metrics for assessing predictive model quality. Based on these metrics, we found that our proposed framework produces a calibrated model that is more accurate, sometimes by an order of magnitude, than engineering models using nominal parameters found in the literature. We also found for many QoIs that the remaining uncertainty was not sufficient to account for discrepancy with experimental data, and that existing models for facility effects do not sufficiently capture experimental trends. Finally, we confirmed through a global sensitivity analysis the prior intuition that anomalous transport dominates model uncertainty, and we conclude by suggesting several paths for future model improvement. We envision that the proposed metrics and procedures can guide the refinement of future model development activities.

The Design and Validation of a High-Precision Angular Vibration Calibration System Based on a Laser Vibrometer.

This paper presents the design and validation of a high-precision angular vibration calibration system based on a laser vibrometer, aimed at meeting the high-precision requirements for measuring small angular vibrations. The system primarily consists of a self-driving angular vibration platform and a laser vibrometer. The platform is isolated from ground interference via an air-floating platform and uses a split-type motor to control the platform, generating specific angular vibrations. Detailed simulations of the platform's modal characteristics and the stability of the spring plates were conducted using the finite element analysis software ANSYS 11. Moreover, fundamental frequency testing and measurement accuracy testing were conducted on the system. Experimental results demonstrate that the system has a fundamental frequency of 2.69 Hz and a maximum measurement error of 0.00172″, confirming the system's effectiveness in dynamic characteristics, stability, and measurement accuracy. This research provides essential technical support for high-precision angular vibration control in spacecraft.

Investigation of Impedance Determination using Two-Point High Frequency Injection Technique for Non-Contact Voltage Measurement System

Energy management facilities are becoming more necessary due to the growth of smart energy and microgrid technologies. Convenient access to information on energy consumption is an advantage for energy planning and management and secure for the operators. Consequently, these conceive the idea of developing non-contact sensor approach to replace the conventional energy measurement while maintain full accessibility to voltage and current information. This paper proposes a method of non-contact conductive voltage measurement with an automated calibration system. The previous application of non-contact voltage measurement systems in the low-voltage range used a method based on the capacitive coupling principle by covering a metal plate around an insulated power line cable. The important factor of measurement accuracy depends on the determination of impedance occurring between the conductors within the cable and the metal plates attached to the cable surface by insulating as a dielectric. The proposed impedance determination process employs a two-point high-frequency signal injection technique that transmits a reference signal to calculate the established parasitic impedance value. From the high-frequency injection technique, the resulting impedance can be calibrated throughout the reverse calculation to measure the actual voltage of the power line. The experimental results of the proposed voltage measurement system can measure the actual voltage of the power line with the capability to calibrate the impedance due to the variation in the environment and eliminate noise errors from the instability under various conditions.

Advanced Phase Diversity Method for telescope static aberration compensation

Accurate calibration is essential for high-performance Adaptive Optics (AO) systems in astronomy. This paper presents a novel methodology for AO systems calibration that preserves the optical path integrity while achieving high-quality results. By eliminating the need for optical modifications, this approach simplifies system complexity and accounts for all static aberrations. The main novelty of this proposal is an advanced Phase Diversity (PD) method for estimating static optical aberrations. Unlike conventional PD techniques, this approach uses the AO system’s deformable mirror to introduce different diversities, eliminating the need for additional calibration hardware. Furthermore, the optimizer Adam is introduced for the first time in this field to estimate the optical aberrations. To evaluate the performance of this new methodology, a set of experiments under varying operating conditions and optimization parameters has been conducted. Results demonstrated that the presented methodology is capable of providing diffraction-limited corrected images with a Strehl Ratio (SR) exceeding 0.80 within 2 min. Furthermore, employing a Manhattan distance-based error function effectively balanced estimation speed and accuracy. The method demonstrated effectiveness across a wide range of aberration magnitudes, achieving an error of 3 nm in the best scenarios. This proposal represents an advancement in the identification and correction of static aberrations in telescope optical systems, directly improving the acquisition of high-quality references for AO sensing.

Multi-cameras calibration System Based Deep Learning Approach and Beyond: A Survey

The process of determining camera settings to deduce geometric attributes from recorded sequences is known as camera calibration. This process is essential in the fields of robotics and computer vision, encompassing both two-dimensional and three-dimensional applications. Traditional calibration methods, however, are time-consuming and require specific expertise. Recent endeavors have demonstrated that learning-based systems can replace the monotonous tasks associated with manual calibrations. Responses have been examined through a range of learning techniques, networks, geometric assumptions, and datasets. A thorough examination of camera calibration systems that rely on learning algorithms is offered in this paper, assessing their advantages and disadvantages. The primary categories of calibration presented are the regular pinhole camera model, distortion camera model, cross-sensor model, and cross-view model. These categories align with current research trends and have diverse applications. As there is no existing standard in this field, a large dataset of calibration has been created, which can be used as a public platform to assess the effectiveness of current methods. This collection consists of both artificially generated and genuine data, including images and videos obtained from various cameras in different locations. The difficulties faced will be analyzed, and alternative avenues for further research will be suggested in the next stage of this project. This survey represents the initial attempt to perform camera calibration using learning-based methods spanning a period of eight years. Our findings indicate that learning-based methods significantly reduce the time and expertise required for calibration while maintaining or improving accuracy compared to traditional methods. Specifically, our research demonstrates a calibration error reduction of up to 20% and speed improvements by a factor of three compared to traditional methods, as well as better adaptability to different camera types and environments.

A Fully Synthesizable Fractional-N Digital Phase-Locked Loop with a Calibrated Dual-Referenced Interpolating Time-to-Digital Converter to Compensate for Process–Voltage–Temperature Variations

This paper presents advancements in the performance of digital phase-locked loop (DPLL)s, with a special focus on addressing the issue of required gain calibration in the time-to-digital converter (TDC) within phase-domain DPLL structures. Phase-domain DPLLs are preferred for their simplicity in implementation and for eliminating the delta–sigma modulator (DSM) noise inherent in conventional fractional-N designs. However, this advantage is countered by the critical need to calibrate the gain of the TDC. The previously proposed dual-interpolated TDC(DI-TDC) was proposed as a solution to this problem, but strong spurs were still generated due to the TDC resolution, which easily became non-uniform due to PVT variation, degrading performance. To overcome these problems, this work proposes a DPLL with a new calibration system that ensures consistent TDC resolution matching the period of the digitally controlled oscillator (DCO) and operating in both the foreground and background, thereby maintaining consistent performance despite PVT variations. This study proposes a DPLL using a calibrated dual-interpolated TDC that effectively compensates for PVT variations and improves the stability and performance of the DPLL. The PLL was fabricated in a 28-nm CMOS process with an active area of only 0.019 mm2, achieving an integrated phase noise (IPN) performance of −17.5 dBc, integrated from 10 kHz to 10 MHz at a PLL output of 570 MHz and −20.5 dBc at 1.1 GHz. This PLL operates within an output frequency range of 475 MHz to 1.1 GHz. Under typical operating conditions, it consumes only 930 µW with a 1.0 V supply.

Highly accurate and sensitive absolute quantification of bacterial strains in human fecal samples

BackgroundNext-generation sequencing (NGS) approaches have revolutionized gut microbiome research and can provide strain-level resolution, but these techniques have limitations in that they are only semi-quantitative, suffer from high detection limits, and generate data that is compositional. The present study aimed to systematically compare quantitative PCR (qPCR) and droplet digital PCR (ddPCR) for the absolute quantification of Limosilactobacillus reuteri strains in human fecal samples and to develop an optimized protocol for the absolute quantification of bacterial strains in fecal samples.ResultsUsing strain-specific PCR primers for L. reuteri 17938, ddPCR showed slightly better reproducibility, but qPCR was almost as reproducible and showed comparable sensitivity (limit of detection [LOD] around 104 cells/g feces) and linearity (R2 > 0.98) when kit-based DNA isolation methods were used. qPCR further had a wider dynamic range and is cheaper and faster. Based on these findings, we conclude that qPCR has advantages over ddPCR for the absolute quantification of bacterial strains in fecal samples. We provide an optimized and easy-to-follow step-by-step protocol for the design of strain-specific qPCR assays, starting from primer design from genome sequences to the calibration of the PCR system. Validation of this protocol to design PCR assays for two L. reuteri strains, PB-W1 and DSM 20016 T, resulted in a highly accurate qPCR with a detection limit in spiked fecal samples of around 103 cells/g feces. Applying our strain-specific qPCR assays to fecal samples collected from human subjects who received live L. reuteri PB-W1 or DSM 20016 T during a human trial demonstrated a highly accurate quantification and sensitive detection of these two strains, with a much lower LOD and a broader dynamic range compared to NGS approaches (16S rRNA gene sequencing and whole metagenome sequencing).ConclusionsBased on our analyses, we consider qPCR with kit-based DNA extraction approaches the best approach to accurately quantify gut bacteria at the strain level in fecal samples. The provided step-by-step protocol will allow scientists to design highly sensitive strain-specific PCR systems for the accurate quantification of bacterial strains of not only L. reuteri but also other bacterial taxa in a broad range of applications and sample types.-oGjUmj5e8MXZDxyDjzcm-Video

Estimating Lab-Quake Source Parameters: Spectral Inversion from a Calibrated Acoustic System.

Laboratory acoustic emissions (AEs) serve as small-scale analogues to earthquakes, offering fundamental insights into seismic processes. To ensure accurate physical interpretations of AEs, rigorous calibration of the acoustic system is essential. In this paper, we present an empirical calibration technique that quantifies sensor response, instrumentation effects, and path characteristics into a single entity termed instrument apparatus response. Using a controlled seismic source with different steel balls, we retrieve the instrument apparatus response in the frequency domain under typical experimental conditions for various piezoelectric sensors (PZTs) arranged to simulate a three-component seismic station. Removing these responses from the raw AE spectra allows us to obtain calibrated AE source spectra, which are then effectively used to constrain the seismic AE source parameters. We apply this calibration method to acoustic emissions (AEs) generated during unstable stick-slip behavior of a quartz gouge in double direct shear experiments. The calibrated AEs range in magnitude from -7.1 to -6.4 and exhibit stress drops between 0.075 MPa and 4.29 MPa, consistent with earthquake scaling relation. This result highlights the strong similarities between AEs generated from frictional gouge experiments and natural earthquakes. Through this acoustic emission calibration, we gain physical insights into the seismic sources of laboratory AEs, enhancing our understanding of seismic rupture processes in fault gouge experiments.