Charge-coupled Device Detection System Research Articles

Characterization of a deep-depletion 4K × 4K charge-coupled device detector system designed for ARIES Devasthal faint object spectrograph

We present the characterization of the charge-coupled device (CCD) system developed for the ARIES Devasthal faint object spectrograph (ADFOSC) instrument on the 3.6 m Devasthal optical telescope (DOT). We describe various experiments performed to tune the CCD controller parameters to obtain optimum performance in single and four-port readout modes. Different methodologies employed for characterizing the performance parameters of the CCD, including bias stability, noise, defects, linearity, and gain, are described here. The CCD has grade-0 characteristics at temperatures close to its nominal operating temperature of −120 ° C. The overall system is linear with a regression coefficient of 0.9999, readout noise of six electrons, and a gain value close to unity. We demonstrate a method to calculate the dark signal using the gradient in the bias frames at lower temperatures. Using the optimized setting, we verify the performance of the CCD detector system on-sky using the ADFOSC instrument mounted on the 3.6 m DOT. Some science targets were observed to evaluate the detector’s performance in both imaging and spectroscopic modes.

Design of CCD test platform of scientific imaging for wide field survey telescope

The wide field survey telescope (WFST) is a new generation survey telescope that is being built in China. Its optical design is a primary-focus system, and its camera is a mosaic charge-coupled device (CCD) camera composed of nine 9 K × 9 K CCD290-99 chips for scientific imaging. A verification platform to test the CCD290-99 chips is designed. The test platform includes a light source system, CCD controller, vacuum Dewar, and refrigerator for cooling the CCD. The CCD controller is a prototype design of the WFST camera that has a high performance, including low readout noise, flexible readout rate configuration, low power dissipation, etc. The digital double correlated sample method is used for video sampling of the CCD’s 16 channels. The specifications of the CCD detector system using a CCD290, such as gain, noise linearity, and crosstalk, are tested using this platform. The test results show that the CCD test platform meets the requirement of the CCD test and the design of CCD controller meets the scientific imaging requirements for the WFST camera.

Dual CCD detection method to retrieve aerosol extinction coefficient profile.

The profile of aerosol extinction coefficient can help understand the air pollution transportation and development of the atmospheric boundary layer. The charge-coupled device (CCD)-laser aerosol detection system (CLADS) was widely used to measure the profile of aerosol extinction coefficient, which has excellent resolution near the ground. Traditionally, a constant aerosol scattering phase function and single scattering albedo (SSA) is assumed when retrieving the profile of aerosol extinction coefficient using the measured signals from CLADS. Sensitivity studies in this research show that aerosol scattering phase function leads to an uncertainty up to 462% of the retrieved profile of aerosol extinction coefficient, while SSA leads to an uncertainty up to 25%. A new method is proposed to derive the profile of aerosol extinction coefficient by using two CCD cameras. The aerosol scattering phase function can be determined by minimizing the difference between profiles of aerosol extinction coefficient from the two CCD cameras without any assumption. The profile of aerosol extinction coefficient can be retrieved with high accuracy by using our optimized aerosol scattering phase function. This method is validated by simulation studies where the relative difference between the pre-parameterized aerosol extinction profile and retrieved aerosol extinction profile is below 6%. This dual CCD detection system is employed in a field measurement and proved to be reliable. Our proposed method can obtain more accurate profile of aerosol extinction coefficient for further works about air pollution and atmospheric boundary layer development.

Design of Ultra-Low Noise and Low Temperature Usable Power System for High-Precision Detectors

In high-precision detector systems, the power supply usually need to be ultra-low noise and stabilized. Design and implementation of an ultra-low noise power supply is described in this paper. We implemented and tested the power system actually in a scientific CCD (Charge-coupled device) detector system, but the design structure could be used in many high-precision detector systems as infrared detector or high-energy particles detectors. The power system uses DC-DC switching regulators and LDO regulators for power generating, uses multi-stage filters for noise reducing. Multi-output power supply with noise about $40~\mu \text {V}_{\mathbf {rms}}$ is achieved, the overall energy efficiency is 68.5%. Besides, the electronic system takes the low temperature as an important consideration, and the system has been tested in an extreme environment as low as 193 K.

A Fully Integrated 0.055% INL X-ray CCD Readout ASIC with Incremental <inline-formula> <tex-math notation="LaTeX">$\Delta \Sigma {\text{ADC}}$</tex-math> </inline-formula>

A fully integrated 100 kHz X-ray charge coupled device (CCD) readout application specific integrated circuit (ASIC) employing delta sigma ( $\Delta \Sigma $ ) digitization is presented. To achieve high linearity with small chip size and low power consumption, the correlated double sampling (CDS) is realized by the $\Sigma \Delta{\rm ADC}$ instead of the analog front end (AFE) as in conventional CCD readout circuits. Besides, the proposed decimation filter features simple structure and eases the integration. The chip is fabricated in $0.35 \upmu\hbox{m}$ CMOS technology and the measured integral nonlinearity (INL) throughout the input dynamic range of ASIC is 0.055% with $35.1 \pm 0.3 \upmu\hbox{V}$ input referred noise. A CCD detection system is built and tested with the sensitivity of CCD being $4 \upmu\hbox{V}/\hbox{e}^-$ . The integration test results show that the readout noise is $11.8 \hbox{e}^ {-} $ at 100 kHz readout pixel rate and the achieved energy spectrum resolution is $168 \hbox{eV} \pm 4.7 \hbox{eV}$ (Full Width at Half Maximum: FWHM) at 5.9 keV.

On-line monitoring system for roller wear with axes shift compensation based on laser-linear charge coupled device

Based on the principle of laser-linear array charge-coupled device (CCD) detection technology, a high accuracy nontouch on-line system for monitoring roller wear is brought forward. The principle and composition of the laser-linear array CCD detection system and the operation process were expatiated. Aiming at the errors of the roller’s axes shifting during the detection process, compensating steps were adopted from the vertical and the parallel direction to the detection surface. This effectively enhanced the accuracy of the detection system. Experiments proved that the accuracy of the system could reach the demand of the practical production process. It provides a new method for high speed, accuracy, and automatic on-line monitoring of roller wear. r shapegear array CCD detection. A simulation-software program is also compiled based on this principle. By using this program, the I/O signals’s data for this system is gained and the detection curves can be drawn automatically.

Comparison of gated and non-gated detectors for double-pulse laser induced plasma analysis of trace elements in iron oxide

Double-pulse laser-induced breakdown spectroscopy (LIBS) is an emerging technique for accurate compositional analysis of many different materials. We present results of collinear double-pulse LIBS for analysis of the trace elements aluminum, phosphorus and boron in sintered iron oxide targets. The samples were ablated in air by double-pulse Nd:YAG laser radiation (6ns pulse duration, laser wavelength of 532nm) and spectra were recorded with an Echelle spectrometer equipped either with a CCD (charge coupled device) or an ICCD (intensified charge coupled device) camera. For the trace elements aluminum and phosphorus, the use of the CCD detector system resulted in considerable higher signal-to-noise ratios and/or better limits of detection compared to the results achieved with the ICCD detector. The use of CCD double-pulse LIBS enables to detect low concentrations of phosphorus with a limit of detection of 10ppm by evaluating the UV line at 214.91nm, which overlaps with a Fe I line. Compared to the ICCD system, the CCD system requires the accumulation of a higher number of laser double-pulses to achieve acceptable signal quality. This can be disadvantageous for elements showing pronounced depletion effects as for the trace element boron in sintered iron oxide targets.

A charge-coupled device-based laser photofragment fluorescence spectrometer for detection of mercury compounds

The use of a charge-coupled device (CCD) camera for the detection of mercuric bromide (HgBr2) vapor at low concentrations by laser photofragment fluorescence (PFF) spectroscopy was investigated. The CCD detection system (camera+monochromator) offers reasonable sensitivity plus spectral information, thus enhancing PFF as a technique for the environmental monitoring of airborne mercury compounds. The experiment used laser radiation at 222 nm to photolyze HgBr2 and produce excited atomic mercury (Hg*). The PFF was monitored at 253.7 nm. Our unenhanced CCD detection limit was about 30 ppb HgBr2 in the absence of air. The CCD response remained linear up to 20 ppm. Observed nonlinearity of the PFF signal at higher concentrations is discussed. With the same collection optics and under the same experimental conditions, the sensitivity of a photomultiplier tube (PMT) with interference filters (253.7 nm) was also investigated for comparison. The detection limit for our PMT system was 10 ppb without signal averaging, but the linear dynamic range ended at 0.7 ppm. It is expected that the CCD detection system would be more versatile for measuring metal compound species by PFF spectroscopy in any future airborne metals monitor.

New precision measurement of the pionic deuteriums-wave strong interaction parameters

The x rays of the pionic deuterium 2p-1s transition were measured with a high resolution crystal spectrometer including a cyclotron trap (a magnetic device to increase the pion stopping density) and a CCD (charge-coupled device) detector system. The 1s strong interaction shift ${\ensuremath{\epsilon}}_{1s}$ and total width ${\ensuremath{\Gamma}}_{1s}$ were determined from the position and line shape of the x-ray peak. The (complex) pionic deuterium s-wave scattering length ${a}_{{\ensuremath{\pi}}^{\ensuremath{-}}d}$ was deduced. Its real part was related to the pion-nucleon scattering lengths, and the isoscalar coupling constant for ${\ensuremath{\pi}}^{\ensuremath{-}}$ absorption was deduced from the imaginary part.

X-ray spectroscopy of the pionic deuterium atom

The low energy X-rays of the pionic deuterium 3 P-1 S transition were measured using a high resolution crystal spectrometer, together with a cyclotron trap (a magnetic device to increase the pion stopping density) and a CCD (charge-coupled device) detector system. The spectrometer resolution was 0.65 eV FWHM for a measured energy of approximately 3075 eV. This energy was measured with a precision of 0.1 eV. Compared to conventional methods, the cyclotron trap allowed for a gain in stopping density of about an order of magnitude. The CCDs had excellent spatial and energy resolutions. Non-X-ray background could therefore be almost completely eliminated. The 1 S strong interaction shift ϵ 1 S and total decay width Γ 1 S were determined from the position and line shape of the X-ray peak. They are ϵ 1S( shift) = 2.43 ± 0.10 eV ( repulsive), Γ 1S( width) = 1.02 ± 0.21 eV , where the statistical and systematic errors were added linearly. The total (complex) pionic deuterium S-wave scattering length a π − d was deduced: a π −d = −0.0259(±0.0011) + i0.0054(±0.0011)m π −1 . From the real part of a π − d a constraint in terms of the isoscalar and isovector πN′ scattering lengths b 0 and b 1 was deduced. From Im a π − d we determined the isoscalar coupling constant for π − absorption: | g 0| = (2.6 ± 0.3) 10 −2 m π −2. The experiments of the pionic hydrogen and deuterium S-wave scattering lengths were analyzed within the framework of a search for i isospin symmetry violation. The data are still compatible with isospin conservation. The scattering lengths deduced from the Karlsruhe-Helsinki phase shift analysis disagree with the present results.

The strong interaction shift and width of the ground state of pionic hydrogen

The 3p-1s transition in pionic hydrogen was investigated with a high-resolution crystal spectrometer system. From the precisely measured transition energy, together with the (calculated) electromagnetic energy, the strong interaction shift of the 1s state was obtained as ϵ 1s = −7.127 ± 0.028(stat.)± 0.036(syst.) eV (attractive). From the natural line width, measured for the first time, we determine the decaywidth of the 1s state: Γ 1s (decay) = 0.97 ± 0.10(stat.)± 0.05(syst.) eV. With the recently calculated electromagnetic corrections the s-wave scattering lengths of an isospin symmetric strong interaction are deduced. The scattering length for elastic scattering of a negative pion on a proton is a π − p→ π − p h = 0.0885±0.00003(stat.)±0.0006(syst.) m π −1. The scattering lengthe for single charge exchange is found to be a π − p→ π 0 n h = −0.136 ± 0.007(stat.) ± 0.003(syst.) m π −1. The experiment was performed at the Paul Scherrer Institute (PSI) in Switzerland. A focussing crystal spectrometer with an array of bent crystals, the cyclotron trap (a magnetic system designed to increase the particle stop density) and a CCD (charge-coupled device) detector system were employed. The results from the pionic hydrogen experiment — together with those from the pionic deuterium experiment — were used to test the isospin symmetry of the strong interaction. The present data are still consistent with isospin sysmmetry.

Appllied Crystallography in the Scanning Electron Microscope Using a CCD Detector*

Abstract The development of a new charge coupled device (CCD)-based detector for the scanning electron microscope (SEM) has allowed high quality backscattered electron Kikuchi patterns (BEKP) suitable for crystallographic analysis to be collected. These BEKPs can be used for crystallographic texture, phase and microstress analysis. This CCD detector system, can also be equipped with a special filter for removing backscattered electrons, which allows us to image low intensity, highly divergent x-ray diffraction (Kossel) patterns. The Kossel patterns are utilized for the accurate measurement of d-spacings suitable foe residual stress and lattice parameter measurements.