Optical Detection System Research Articles

Design method of optical detection systems based on transimpedance amplifiers

Designing detection systems based on transimpedance amplifiers is a complex task because noise, frequency response, and stability are coupled constraints. This work presents a straightforward design method of detection systems based on transimpedance amplifiers. We take into account the objectives, scope of the design, and requirements and specifications, including the input signal levels. According to the small-signal model, the noise and stability are analyzed in detail. We present a systematic procedure to search for the acceptable values of the feedback network components based on these analyses. Then, we define a merit function to compare the performance of the acceptable combinations of feedback network components. For every acceptable combination, the function gives a quantitative measure of the degree of compliance for each design parameter: signal-to-noise ratio, highest operating frequency, and phase margin. As an example, we apply the method to optimize the design of an optical detection system using a PIN photodiode and a low-noise operational amplifier.

Fiber optic sensor array fork-lug flexible monitoring of large components.

To realize the flexible monitoring and online pose correction of the complex assembly of large components, an optical fiber sensor array-based tooling condition monitoring network was built. First, an ANSYS simulation analysis was conducted to obtain the strain sensitive position of the tooling, and the maximum deformation was 0.0368 mm; then, the combination relationship between the monitoring position of the fiber grating sensor and the test data was determined. Next, a flexible sensor packaging structure was designed to achieve optimal strain sensitivity for ensuring flexible assembly. Finally, a three-dimensional reconstruction calculation model of stress field distribution and assembly pose adjustment was developed. The changes in the stress field distribution caused by different assembly problems were analyzed, and the corresponding pose correction parameters were solved. The results show that the inversion accuracy of the position deformation of the optical fiber sensor was better than 0.0058 mm, and the minimum correction accuracy of the position was 0.17 mm. The optical fiber flexible detection system works with the assembly structure to realize the intelligent assembly of large components and addresses the limitations of existing three-dimensional digital measurement processes due to environmental vibration, test openness, and other factors.

Research on passive low-light-level optical fiber endoscope detection system

A passive low-light-level optical fiber endoscope detection imaging system is studied by combining optical fiber endoscope technology with high sensitivity EMCCD low-light-level imaging technology. On the basis of designing the overall system, the hardware with dual-mode switching function is constructed by using ordinary color camera and low-light-level camera. The USAF1951 resolution board is used to test the resolution of the system. The results show the white light lateral resolution of the system of 70.1 µm, the night vision lateral resolution of 180 µm. The average value of Bhattacharyya coefficient is 0.8681, indicating that the system can effectively avoid light leakage. In the environment of illuminance of 0.5 Lux, the image frame rate of the system is greater than 25 Hz, indicating that the system has fast imaging speed under low illumination. The imaging gain of the system can be up to 1000 times, indicating that the high-sensitivity low-illuminance camera has excellent imaging ability under low light conditions. After calculation, the system has a field of view of 66.4 cm2, which is more suitable for observing rodents. The passive low-light-level optical fiber endoscope detection imaging system has highly sensitive detection performance under weak light environment such as rodent caves, where active lighting is not suitable.

Optical modulation biosensing system for rapid detection of biological targets at low concentrations.

In many sensitive assays, target molecules are tagged using fluorescently labeled probes and captured using magnetic beads. Here, we introduce an optical modulation biosensing (OMB) system, which aggregates the beads into a small detection area and separates the signal from the background noise by manipulating the laser beam in and out of the cluster of beads. Using the OMB system to detect human interleukin-8, we demonstrated a limit of detection of 0.02 ng/L and a 4-log dynamic range. Using Zika-positive and healthy individuals' serum samples, we show that the OMB-based Zika IgG serological assay has 96% sensitivity and 100% specificity.

Utilizing a Biology-Driven Approach to Map the Exposome in Health and Disease: An Essential Investment to Drive the Next Generation of Environmental Discovery.

Background:Recent developments in technologies have offered opportunities to measure the exposome with unprecedented accuracy and scale. However, because most investigations have targeted only a few exposures at a time, it is hypothesized that the majority of the environmental determinants of chronic diseases remain unknown.Objectives:We describe a functional exposome concept and explain how it can leverage existing bioassays and high-resolution mass spectrometry for exploratory study. We discuss how such an approach can address well-known barriers to interpret exposures and present a vision of next-generation exposomics.Discussion:The exposome is vast. Instead of trying to capture all exposures, we can reduce the complexity by measuring the functional exposome—the totality of the biologically active exposures relevant to disease development—through coupling biochemical receptor-binding assays with affinity purification–mass spectrometry. We claim the idea of capturing exposures with functional biomolecules opens new opportunities to solve critical problems in exposomics, including low-dose detection, unknown annotations, and complex mixtures of exposures. Although novel, biology-based measurement can make use of the existing data processing and bioinformatics pipelines. The functional exposome concept also complements conventional targeted and untargeted approaches for understanding exposure-disease relationships.Conclusions:Although measurement technology has advanced, critical technological, analytical, and inferential barriers impede the detection of many environmental exposures relevant to chronic-disease etiology. Through biology-driven exposomics, it is possible to simultaneously scale up discovery of these causal environmental factors. https://doi.org/10.1289/EHP8327

Optical Multiparameter Detection System Based on a Broadband Achromatic Metalens Array

AbstractMetalenses, known as flat metasurface lenses based on subwavelength phase modulations, have been widely applied to compact and multifunctional optical devices due to their high flexibility in controlling light. However, most metalenses only operate at single wavelength, limiting their practical applications. In this paper, an achromatic metalens array (AMLA)‐based optical multiparameter detection system, for a near‐infrared spectrum from 1310 to 1550 nm, is reported. Such system can simultaneously detect the spatially varying polarization and phase gradient of the broadband beam. Its performance is experimentally characterized at wavelengths of 1310, 1430, and 1550 nm. Average errors of 18 selected polarization states are respectively 6.40%, 6.74%, and 6.02%. Average errors of phase gradients of seven different incident light are 8.93%, 7.44%, and 5.68%. This system can find applications in structured light detection, quantum optics, and polarization imaging.

Joint equalization of CD and RSOP using a time–frequency domain Kalman filter structure in Kramers–Kronig system

Kramers–Kronig (KK) system is a direct detection (DD) optical short-reach interconnection system which is suitable for high capacity data center interconnect (DCI) applications. For this kind of short-reach high capacity polarization-division multiplexing (PDM) optical transmission system, the fiber channel impairments contain chromatic dispersion (CD) and rotation of state of polarization (RSOP) will lead to a severe signal distortion and need to be equalized. This paper proposed a time–frequency domain Kalman filter scheme for joint equalization of CD and RSOP simultaneously in KK system. The proposed scheme is capable of tracking the fast RSOP in time domain and equalizing CD in frequency domain using a window-split structure. The performance of the Kalman scheme is investigated in a 28GBaud PDM 16QAM DD system with KK receivers. The simulation results prove that the proposed Kalman scheme exhibits a good performance of RSOP tracking ability up to speed of 2.5 Mrad/s, with a large accumulated CD tolerance as large as 2040 ps/nm at a low OSNR penalty. The results also show the proposed scheme has a comparable computational complexity compared with a generally used scheme which includes a CD compensation, combined with polarization demultiplexing algorithm constant modulus algorithm (CMA) and multiple modulus algorithm (MMA).

Toward Development of a Label-Free Detection Technique for Microfluidic Fluorometric Peptide-Based Biosensor Systems.

The problems of chronic or noncommunicable diseases (NCD) that now kill around 40 million people each year require multiparametric combinatorial diagnostics for the selection of effective treatment tactics. This could be implemented using the biosensor principle based on peptide aptamers for spatial recognition of corresponding protein markers of diseases in biological fluids. In this paper, a low-cost label-free principle of biomarker detection using a biosensor system based on fluorometric registration of the target proteins bound to peptide aptamers was investigated. The main detection principle considered includes the re-emission of the natural fluorescence of selectively bound protein markers into a longer-wavelength radiation easily detectable by common charge-coupled devices (CCD) using a specific luminophore. Implementation of this type of detection system demands the reduction of all types of stray light and background fluorescence of construction materials and aptamers. The latter was achieved by careful selection of materials and design of peptide aptamers with substituted aromatic amino acid residues and considering troponin T, troponin I, and bovine serum albumin as an example. The peptide aptamers for troponin T were designed in silico using the «Protein 3D» (SPB ETU, St. Petersburg, Russia) software. The luminophore was selected from the line of ZnS-based solid-state compounds. The test microfluidic system was arranged as a flow through a massive of four working chambers for immobilization of peptide aptamers, coupled with the optical detection system, based on thick film technology. The planar optical setup of the biosensor registration system was arranged as an excitation-emission cascade including 280 nm ultraviolet (UV) light-emitting diode (LED), polypropylene (PP) UV transparent film, proteins layer, glass filter, luminophore layer, and CCD sensor. A laboratory sample has been created.

Modeling of laser optical detection system for detecting target’s sensitivity and analysis of the impact of optical heterodyne detection performance

Aiming at the problem of random interference existing in traditional laser detection target signal, in this paper, we introduce the mechanism of optical heterodyne imaging, study the active laser photoelectric detection system. From the angle of environmental illumination and target reflected laser illumination, we establish the model of the detection system’s sensitivity. According to the parameters of laser photoelectric detection system, we analyze the design method of optical heterodyne imaging detection system. Combining with characteristic parameters such as transmitting laser power, background illumination, target characteristic and local oscillator light source power, we deduce the output current signal function of photoelectric detection receiver, and give the signal to noise ratio (SNR) model of detection system. Through calculation and experimental analysis, in the active laser detection system, with the increase of the difference between the target reflected laser illumination and the background environment illumination, the SNR and the sensitivity of the system are improved. The SNR of the system is obviously changed by changing the power of local oscillator source. The experimental results are in good agreement with the calculated results.

Muscle Strength and Physical Performance Are Associated with Reaction Time Performance in Older People.

Background: Functional mobility and muscle strength are well known risk factors for sarcopenia. Furthermore, possible associations have been suggested between predisposing factors of sarcopenia and reaction time among the elderly. This study aims to analyze possible associations of functional mobility and muscle strength and reaction times in a population of people aged >60 years. Methods: A total of 290 older people (69.35 ± 5.55 years) participated in this study. The following parameters were assessed: optoacoustic lower-limb reaction time (OALLRT); acoustic lower-limb reaction time (ALLRT); optic lower-limb reaction time (OLLRT, using an optical detection system), functional mobility (through the timed up-and-go test) and muscle strength (using a dynamometer). Results: Our results show that lower values of muscle strength were associated with increased reaction times in OALLRT (β = −0.170; 95% confidence interval −0.011–0.000; R2 = 0.237; p = 0.035) and in ALLRT (β = −0.228; 95% confidence interval −0.011–0.002; R2 = 0.199; p = 0.006). Conclusion: Increased muscle strength (which at low values are risk factors for sarcopenia) was associated with decreased reaction times in people >60 years of age.

All-fiber transient phase noise characterization of polarization maintaining Yb-doped fiber amplifiers

We demonstrated an all-fiber phase noise measurement technique to detect transient phase variation of polarization maintaining Yb-doped fiber amplifier based on active phase locking of an optical heterodyne detection system. The root mean square, power spectral density, and drift velocity in the phase noise were analyzed for both core-pumped single clad fiber amplifier and clad-pumped double-clad fiber amplifier. The phase noise was further analyzed in terms of the seed laser power, amplifier output power, and fiber optic component configurations. The phase drift velocity measurements at various amplifier output powers indicated the optical phase were closely related to the temperature variations.

Large bandwidth and high-efficiency plasmonic quarter-wave plate.

A large bandwidth and high-efficiency subwavelength quarter-wave plate (QWP) is an indispensable component of an integrated miniaturized optical system. The bandwidth of existing plasmonic quarter-wave plates with a transmission efficiency of more than 50% is less than 320 nm in the near-infrared band. In this paper, a metallic quarter-wave plate with a bandwidth of 600 nm (0.95-1.55 µm) and an average transmittance of more than 70% has been designed and shows excellent potential to be used in miniaturized optical polarization detection systems and as an optical data storage device. For TE mode incident waves, this miniaturized optical element can be equivalent to a Fabry-Pérot (FP) resonator. Meanwhile, for the TM mode incident wave, the transmission characteristics of this structure are controlled by gap surface plasmon polaritons (G-SPPs) existing in the symmetric metal/insulator/metal (MIM) configuration.

Global imaging with high resolution region of interest using fusion data based on dual-field of view detection system.

X-ray micro-computed tomography (CT) is an important tool for high-resolution three-dimensional imaging. But one limitation of micro-CT is the compromise between resolution and fields of view (FOV). In this paper, we develop an x-rays dual-FOV optical coupling detection (DFOCD) system for global imaging with high-resolution region of interest (ROI). In DFOCD system, the beam splitter separates lights to form two sub-optical paths, two objectives with different FOV and magnification are used in the two sub-optical paths for dual-FOV imaging. Then a data fusion method is proposed to register and fuse dual-FOV data. Reconstructed images are obtained based on back projection filtering algorithm using fusion data. Dual-FOV data are collected simultaneously in DFOCD system, which precludes artifacts in fusion images from phantom movement or changes in two acquisitions on common micro-CT, and also saves scanning time. Simulation and experimental results show that details in ROI and global morphology of phantoms are correctly reconstructed. Bright ring artifacts of ROI caused by truncated data are corrected in reconstruction images. Therefore, global imaging with high-resolution ROI of samples can be obtained by single scan experiment using DFOCD system and data fusion method, which is expected to expand the application of micro-CT.

Design of projection optical system for 3D defect detection on PCB

According to the practical experience of PCB defect detection in semiconductor industry, a projection optical system suitable for structured light detection device is designed by using a DMD chip. In order to realize the lateral projection of structured light stripe and improve the quality of system projection, the design of tilt back group of projection lens is adopted and the projection size is 57×32mm.The simulation results show that the illumination uniformity of the projection system on the measured surface is more than 85%, the fringe contrast is larger than 0.5, and the maximum height of the measuring device is 5mm, which provides a guarantee for practical application of structured light fringe for 3D defect detection on PCB.

Development of solar cell for large area position detection: proof of concept

Detecting and analyzing a moving body position are helpful in many fields, such as medicine, sports performance, virtual reality and many more. Therefore, researchers try to develop a tool or a system that helps to detect the motion and tracking its position. This paper shows how a Si solar cell can be modified to function as a Position Sensitive Detector (PSD), which could be used as a large area detector in a position detection system. To develop the new detector, we modeled and simulated the modified solar cell by TCAD simulation tools to calculate the detected photocurrent as a function of the position of an incident laser beam sourced by the moving object. Further, an optical position detection system is implemented containing the modified solar cell, a signal amplifier and a microcontroller. The output is then displayed on a Laptop. By measuring the same simulated output photocurrents, it is found that the measured system output matches the simulation results. This proposed position detection system is relatively cheap because it does not contain high precision optical image building components such as lenses and mirrors. Besides, the proposed system could substitute the optical system by using a large area PSD made from a broad array of solar cells. The electronics are also much more straightforward than those in systems based on image processing. So, it has a high-speed response. The error assessment of the proposed system showed a low position detection error of less than 10%.

An Investigation of the Thermal and Dielectric Properties of Nickel Sulfate Hexahydrate Single Crystal for Sensors, Bandpass Filters and Optical Applications

In the present work, a good-quality nickel sulfate hexahydrate (NSH) single crystal measuring 30 × 20 × 15 mm3 was grown via a slow evaporation solution technique (SEST). NSH single crystal is an inorganic material and is widely used in optical applications, UV sensors, and missile detection systems, among others. The grown crystal was characterized using powder x-ray diffraction (PXRD), UV-visible spectroscopy, microhardness test and etching analysis. Photoacoustic spectroscopy (PAS) was used to identify the thermal diffusivity of the grown crystal. The thermal diffusivity of the NSH crystal was found to be superior to that of various common nonlinear optical (NLO) materials, and is thus suitable for use in optical and sensor applications. Differential scanning calorimetry (DSC) was utilized to determine the material decomposition at a certain temperature. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were performed to identify the melting point of the grown crystal. The dielectric analysis showed that the crystal has low dielectric loss, fewer defects, and better optical properties, and is suitable for NLO applications. Thermal analysis showed that the grown crystal can be utilized for a wide array of applications including optical communications, UV bandpass filters, UV sensors, harmonic generation, and missile detection systems.

Development of a Microfluidic Platform for Trace Lipid Analysis.

The inherent trace quantity of primary fatty acid amides found in biological systems presents challenges for analytical analysis and quantitation, requiring a highly sensitive detection system. The use of microfluidics provides a green sample preparation and analysis technique through small-volume fluidic flow through micron-sized channels embedded in a polydimethylsiloxane (PDMS) device. Microfluidics provides the potential of having a micro total analysis system where chromatographic separation, fluorescent tagging reactions, and detection are accomplished with no added sample handling. This study describes the development and the optimization of a microfluidic-laser induced fluorescence (LIF) analysis and detection system that can be used for the detection of ultra-trace levels of fluorescently tagged primary fatty acid amines. A PDMS microfluidic device was designed and fabricated to incorporate droplet-based flow. Droplet microfluidics have enabled on-chip fluorescent tagging reactions to be performed quickly and efficiently, with no additional sample handling. An optimized LIF optical detection system provided fluorescently tagged primary fatty acid amine detection at sub-fmol levels (436 amol). The use of this LIF detection provides unparalleled sensitivity, with detection limits several orders of magnitude lower than currently employed LC-MS techniques, and might be easily adapted for use as a complementary quantification platform for parallel MS-based omics studies.

Methods of detecting and measuring fugitive methane emissions from elements of the gas transmission infrastructure – the results of GERG project Detection and Measurement of Fugitive Emissions of Natural Gas from the Transmission Systems

The article presents the results of the project carried out by GAZ-SYSTEM in cooperation with 5 other European gas Transmission System Operators (TSO) – ENAGAS, Fluxys, Gasunie, Snam and GRTgaz. The objective of the project was to investigate and identify the most useful devices for detecting and measuring methane emissions from infrastructure components typical for the TSO. The market analysis showed that methane detectors utilizing different principles of operation are available, but there are much fewer devices for measuring emission rates. 5 devices were selected for tests: 3 exclusively for detection based on the D-1 (semiconductor sensor), D-2 (infrared optical gas detection system), D-3(laser technology) principle of operation, and 2 devices that also enable emissions measurement – P-1 (ultrasound imaging) and P-2 (quantitative optical gas imaging). Laboratory tests were carried out in March 2020 at the Enagás’ Metrological & Innovation Center (M&I); according to the approved program, methane leaks were generated from deliberately unsealed valves, flanges, threaded and open-ended pipe connections. Field tests were carried out at the measuring gas station near the M&I. The main purpose of the research was to verify the accuracy of the selected measuring instruments. It was carried out at different flowrate and various methane concentrations in the gas escaping from the components. Ease of use of the devices, their speed and range of operation were assessed. The results showed both the advantages and limitations of each device, and they clearly indicated that the assessment of methane emissions from gas transmission infrastructure components requires the use of at least two different devices. The results indicate that sniffer devices, characterized by the fact that the probe must be placed in the vicinity of the source of emission, give results similar to the FID Detector, most commonly used in Leak Detection and Repair (LDAR) programs, but can be used in a wider range of methane concentrations. D-3 has a fast response time and a wide measuring range, but their unit of measurement i.e. ppm-m prevents the conversion of the results into methane concentration without additional measurements of the distance between the leak and the device. The P-1 and P-2 allow to measure the emissions in real time, while the measurement errors for both devices are comparable, ranging from about 70% to 100%.

Energy dependency of dose response function of a Gd2O2S scintillator detection system for spot-scanning carbon-ion and proton radiotherapy

To ensure quality assurance (QA) of scanning proton and carbon-ion therapy doses, an efficient and reliable method to measure the energy dependency of the dose response function (DRF) of an optical scintillator detection system (OSDS), is required. We present a calibration process that corrects the non-linear sensitivity of the imager's electronic readings into linear light intensities. After calibration, a digital readout of green colored stimulated-light emission (SLE) are converted to nominal SLE (N_SLE). The slope of N_SLE as a linear function of dose is labelled as K-factor. The K-factors for 7 energies of carbon-ion and proton have been measured. For the highest (424.89 MeV/u) and lowest (97.87 MeV/u) energies of carbon-ion, the K-factors are 0.96 and 0.76 N_SLE/Gy. For the highest (218.56 MeV) and lowest (53.04 MeV) energies of protons, the K-factors are 0.96 and 0.86 N_SLE/Gy. The variation of K-factor for its energy dependence are 18% and 11% between lowest and highest energies of carbon-ion and proton beam respectively. Similar trending of the K-factor was seen for the red and blue colors with respect to the green color channel, although the signal magnitude was lower for the red channel. The OSDS dose response is weakly dependent on the energy of the carbon-ion and proton beams regardless of color channel. The energy-dependency of DRF and interactive capability of OSDS can be used to create efficient dosimetry tools to measure data for spot-scanning carbon-ion and proton radiotherapy.

High-performance graphene/Si hybrid photodetector with a PMMA coating layer

Photodetectors with ultrahigh responsivity are meaningful for weak optical signal detection in the fields of biomedicine science and environmental monitoring. Graphene/Si hybrid photodetectors with ultrahigh photoresponsivity have already been reported. However, with all atoms exposed to the environment, graphene-based devices often show low stability. Here, the PMMA layer assisting the graphene transfer process has been retained on the surface of graphene during the fabrication process of the graphene/Si hybrid photodetector, and a high stability graphene photodetector with ultrahigh responsivity (>106 A W−1 for white LED illumination) has been successfully demonstrated. The fabricated graphene/Si hybrid photodetectors may have the potential to be utilized in functional near-infrared spectroscopy systems or underwater wireless optical communication systems for weak optical signal detection.