Light Spectrometer Research Articles

Heat treatment impact on structural-rheological properties of high-parafin oil

Relevance. The pipeline transportation of heavy oils from the extraction site to the processing point is associated with serious problems due to their high viscosity and pour point. Oil deposits form quickly during pumping and causing flow reduction in pipe. Moreover, the increased content of hydrogen sulfide and chloride salts leads to increased rate of corrosion. Structural and mechanical properties and the yield point of highly pourable paraffinic oils depend on a variety of factors, like oil thermostatting temperature. Studying the impact of the heat treatment temperature of highly paraffinic resinous oil on its mobility will allow reducing energy consumption and optimizing the technology of oil pumping and transporting in winter conditions. Aim. To identify the critical temperature ranges for heat treatment of highly paraffinic resinous oil from the Yuzhno-Mayskoe field based on the analysis of data on structural and rheological behaviors, composition of oil sediments and changes in the radii of oil aggregates formed in the studied oil under various heat treatment conditions. Methods. Oil rheological properties were determined using a HAAKE Viscotester iQ rotational viscometer with HAAKE RheoWin measuring device and control system; oil pour point was analyzed using “Kristall” low-temperature indicator of petroleum products meter; asphaltenes were isolated using the “cold” Golde method; oil composition was determined by column liquid adsorption chromatography; oil particle size was recorded by a Photocor Complex spectrometer for dynamic and static light scattering with DynaLS data processing program. Results. The authors have studied heat treatment temperature impact on the viscosity-temperature and energy characteristics of highly paraffinic tarry oil, formation and composition of asphalt, resin and paraffin deposits. They established that the critical temperature of heat treatment is 40°C. At this temperature the densest crystallization structure is formed in the studied oil, characterized by high values of both viscosity, intensive formation of sediment, activation energy of viscous flow and internal energy of destruction of the dispersed structure. It was shown that with photon correlation spectroscopy, during oil heat treatment at 40°C, a spontaneous size increase of oil aggregates occurs in the temperature range of 35–25°C.

A Handheld Colorimeter for Remote and Onsite Recognition of Baking Levels at High Temperature — Pork Floss as a Case Study

AbstractPork floss is a common dried meat product in Asia. The endpoint of the baking process is traditionally determined by subjective human experts and indirect temperature measurements, which can often result in unstandardized production. Current colorimeters are unavailable for onsite measurement due to limitations associated with contact measurement and environmental temperature. Instead of the abovementioned human experts and tabletop colorimeters, a handheld colorimeter was built based on the expertise of human specialists and utilizing a tabletop colorimeter and other optical steps. First, the selected samples were used to determine the upper and lower limits distinguishing light, medium, and heavy baking levels by using a tabletop colorimeter. Second, independent light sources and spectrometers were utilized to choose the characteristic and reference wavelengths at 450 and 830 nm, separately. Third, the handheld colorimeter, instead of human expert observation, was designed with functions such as distance sensing and Internet of Things capabilities. The baked index was derived from the calibration reflection and established statistical models. Here, the calibration reflection was defined by the normalized intensity at 450 nm relative to 830 nm, and statistical models were founded from the determined samples of upper and lower limits at 95–700 mm. The developed handheld colorimeter demonstrated high agreement rates of 96.84% and 93.86% in separate comparisons with tabletop colorimeters and human experts, respectively. This work indicated the accurate and stable recognition of samples within two limits and overall. Field validation confirmed the performance of remote, economic, and onsite recognition against environmental temperature and noise.

Time-domain Vernier effect-based optical fiber sensor.

In this Letter, we demonstrate an easy-to-fabricate time-domain Vernier-effect-based sensor. An all-fiber variable optical delay line (VODL) is utilized to drive an OPD scan of two interferometers simultaneously, and fiber Bragg gratings are used to filter out two slightly detuned time-domain interferometric signals. Then two normalized interferograms with different spatial frequencies can be achieved and utilized to generate an envelope modulation, viz., a Vernier envelope, with enhanced sensitivity in comparison to the native state of the interferometers used. The sensitivity magnification factor of our structure can be regulated simply via altering the resonant wavelength difference of FBGs rather than optimizing the OPDs of the interferometers. The proposed sensor is independent of the precise and complicated fabrication procedures. The Vernier signal can be demodulated without a broadband light source and spectrometer. We argue that the proposed structure may inspire a new concept for constructing simple and cheap Vernier effect-based sensors that are well suited for practical applications.

Influence of fitting algorithms on thickness determination during monitoring of optical coatings

The monitoring of thickness evolution during the deposition of optical interference coatings is widely performed by transmittance measurements and continuous comparison with theoretical models. The fitted thickness of the actual layer is influenced by the quality of the signal. Effects from light path, substrate and spectrometers result in deviations because these are often not part of the models. We show an implementation of these unmodeled effects in the fitting algorithms. The outcome of different configurations while coating the same optical filter design is compared. Additionally, the time consumption of these strategies is investigated to verify their suitability for production.

High-precision non-invasive RBC and HGB detection system based on spectral analysis.

Non-invasive blood composition analysis based on dynamic spectrum (DS) theory has gained significant attention due to its non-invasive, simple, and fast performance. However, most of the multi-wavelength photoplethysmography (PPG) detection devices used to obtain DS are composed of halogen light sources and spectrometers and cannot detect effective PPG signals in the visible light short band (400-620nm), which limits the detection accuracy of blood components with significant absorption spectral differences in that band. Therefore, this paper designs a multi-wavelength spectral acquisition system that can measure high signal-to-noise ratio (SNR > 65dB) PGG signals at wavelengths of 405, 430, 450, 505, 520, and 570nm and combines this system with a halogen lamp spectrometer acquisition system for non-invasive blood component detection. Furthermore, this paper collects the DS of 272 subjects with the combined system and establishes a predictive model for DS with the content of red blood cell (RBC) and hemoglobin (HGB) components. The results show that, compared with the halogen lamp spectrometer acquisition system, the correlation coefficient (Rp) of RBC and HGB prediction model established by the combined system has increased by 0.0619 and 0.0489, respectively, and the root mean square error (RMSE) has decreased by 0.08 1e12/L and 0.85g/L, which confirm the feasibility of the designed multi-wavelength spectrum acquisition system to enhance the accuracy of blood component detection.

Spectral correction of light emitting diodes enables accurate hydration ratio calculation using narrowband diffuse reflectance spectroscopy.

Light emitting diodes (LEDs) are commonly utilized for tissue spectroscopy due to their small size, low cost, and simplicity. However, LEDs are often approximated as single-wavelength devices despite having relatively broad spectral bandwidths. When paired with photodiodes, the wavelength information of detected light cannot be resolved. This can result in errors during chromophore concentration calculations. These errors are particularly apparent when analyzing water and fat in the 900 to 1000nm window where the spectral bandwidth of LEDs can encompass much of the analysis region, resulting in intense crosstalk. We utilize and present a spectral correction (SC) algorithm to correct for the spectral bandwidth of LEDs. We show the efficacy using a narrowband technique of spectrally broad and overlapping LEDs. Narrowband diffuse reflectance spectroscopy (nb-DRS), a technique capable of quantifying the hydration ratio () of turbid media, was utilized. nb-DRS typically requires a broadband light source and spectrometer. We reduce the hardware to just five LEDs and a photodiode detector, relying on SC to compensate for spectral crosstalk. The effectiveness of our SC approach was tested in simulations as well as in an emulsion phantom and limited selection of human tissue. In simulations, we show that calculated errors increased with the spectral bandwidth of LEDs but could be corrected using SC. Likewise, in emulsions, we found an average error of 8.7% (maximum error 14%) if SC was not used. By contrast, applying SC reduced the average error to 2.2% (maximum error of 6.4%). We show that despite utilizing multiple, spectrally broad, and overlapping LEDs, SC was still able to restore the performance of our narrowband method, making it comparable to a much larger full broadband system.

Dissolved organic carbon export in a small, disturbed peat catchment: Insights from long‐term, high‐resolution, sensor‐based monitoring

AbstractUnderstanding dissolved organic carbon (DOC) export dynamics from carbon‐rich environments is critical. Peatlands act as terrestrial carbon stores, and consequently supply substantial amounts of DOC to drainage. This DOC flux is temporally heterogeneous and subject to long‐ and short‐term variability. Ultrahigh temporal resolution sampling (< hourly) is still in‐frequent in peatland catchments. We used a field‐deployable —ultraviolet–visible light spectrometer (Spectro::lyser™) and monitored DOC flux from a temperate peatland over 31 months to examine seasonal and event dynamics. DOC concentration varied from 6.8 to 63.5 mg L−1, in the higher reported range for peatlands and showed clear seasonal (high‐summer, low‐winter) variability coinciding with elevated biological productivity in the peatland. Discharge was an unreliable predictor of instantaneous DOC concentration overall, with antecedent water temperatures proving the most reliable predictor overall. Discharge drove total DOC export in the catchment, where the top 10% of flow events, accounted for 41.3% of all DOC exported—increasing to 84.6% in the top 50% of flow events. Total estimated catchment DOC flux was sensitive to measurement frequency: increasing from every 30 min to daily altered export estimates by < 1%, increasing to > 10% at 1‐week intervals. The variation in estimated flux increased approximately linearly with reduced sampling frequency, reaching > 40% at monthly intervals. High‐resolution data reveal the large amount of within‐site complexity of DOC export dynamics in a temperate peatland and provide evidence on the subsequently recommended sampling frequency for the future elucidation of detailed DOC budgets in these environments.

Polarized light diffuse reflectance FT-NIR MEMS spectrometer enabling the detection of powder samples through a thin plastic layer.

Polarized scattered light Fourier transform infrared (FTIR) spectroscopy is used for measuring the absorbance of highly scattering materials overcoming the multiple scattering effect. It has been reported for in vivo for biomedical applications and in-field for agricultural and for environmental monitoring. In this paper, we report a polarized light microelectromechanical system (MEMS)-based FTIR in the extended near infrared (NIR) that utilizes a bistate polarizer in a diffuse reflectance measurement setup. The spectrometer is capable of distinguishing between single backscattering from the uppermost layer and multiple scattering from the deep layers. The spectrometer has a spectral resolution of 64c m -1 (about 16nm at a wavelength of 1550nm) and operates in the spectral range of 4347c m -1 to 7692c m -1 (1300nm to 2300nm). The technique implies de-embedding of the MEMS spectrometer polarization response by normalizing its effect; this is applied on three different samples: milk powder, sugar, and flour in plastic bags. The technique is examined on different scattering size particles. The scattering particles diameter's range is expected to vary from 10µm to 400µm. The absorbance spectra of the samples are extracted and compared to the direct diffuse reflectance measurements of the samples, showing good agreement. By using the proposed technique, the calculated error for the flour was decreased from 43.2% to 2.9% at 1935nm wavelength. The wavelength error dependence is also reduced.

Optical Frequency Comb Frequency-division Multiplexing Dispersive Interference Multichannel Distance Measurement

An optical frequency comb (OFC) frequency-division multiplexing dispersive interference multichannel distance measurement method is proposed. Based on the OFC dispersive interference, the wide OFC spectrum is divided into multiple channels using a wavelength-division multiplexer. Under the existing light source and spectrometer, a single interference system can realize six channels of the high-precision parallel absolute distance measurement. The influence of the spectrum width and shape on the performance of the distance measurement channel is analyzed. The ranging accuracy of six channels is higher than ± 4 μm under the optimization of a nonuniform discrete Fourier transform and Hanning window.

Mechanical Properties of a 3 Dimensional–Printed Transparent Flexible Resin Used for Vascular Model Simulation Compared with Those of Porcine Arteries

PurposeTo develop a vascular intervention simulation model that replicates the characteristics of a human patient and to compare the mechanical properties of a 3-dimensional (3D)–printed transparent flexible resin with those of porcine arteries using the elastic modulus (E) and kinetic friction coefficient (μk). Materials and MethodsResin plates were created from a transparent flexible resin using a 3D printer. Porcine artery plates were prepared by excising the aorta. E values and the adhesive strengths of the resin and arterial surfaces toward a polyethylene plate, were measured with a tensile-compressive mechanical tester. Resin transparency was measured using an ultraviolet-visible light spectrometer. The μk value of the resin plate surface after applying silicone spray for 1–5 seconds and that of the artery were measured using a translational friction tester. ResultsE values differed significantly between the arteries and resin plates at each curing time (0.20 MPa ± 0.04 vs 8.53 MPa ± 2.37 for a curing time of 1 minute; P < .05). The resin was stiffer than the arteries, regardless of the curing times. The visible light transmittance and adhesive strength of the resin decreased as the curing time increased. The adhesive strength of the artery was the lowest. The μk value of the silicone-coated resin surface created by applying silicone for 2–3 seconds (thickness of the silicone layer, 1.6–2.0 μm) was comparable with that of the artery, indicating that the coating imparted a similar slippage to the resin as to the living artery. ConclusionsA transparent flexible resin is useful for creating a transparent and slippery vascular model for vascular intervention simulation.

Intelligent synthesis of hyperspectral images from arbitrary web cameras in latent sparse space reconstruction

&lt;abstract&gt;&lt;p&gt;Synthesizing hyperspectral images (HSI) from an ordinary camera has been accomplished recently. However, such computation models require detailed properties of the target camera, which can only be measured in a professional lab. This prerequisite prevents the synthesizing model from being installed on arbitrary cameras for end-users. This study offers a calibration-free method for transforming any camera into an HSI camera. Our solution requires no controllable light sources and spectrometers. Any consumer installing the program should produce high-quality HSI without the assistance of optical laboratories. Our approach facilitates a cycle-generative adversarial network (cycle-GAN) and sparse assimilation method to render the illumination-dependent spectral response function (SRF) of the underlying camera at the first part of the setup stage. The current illuminating function (CIF) must be identified for each image and decoupled from the underlying model. The HSI model is then integrated with the static SRF and dynamic CIF in the second part of the stage. The estimated SRFs and CIFs have been double-checked with the results by the standard laboratory method. The reconstructed HSIs have errors under 3% in the root mean square.&lt;/p&gt;&lt;/abstract&gt;

BEM-Based Magnetic Field Reconstruction by Ensemble Kálmán Filtering

Abstract Magnetic fields generated by normal or superconducting electromagnets are used to guide and focus particle beams in storage rings, synchrotron light sources, mass spectrometers, and beamlines for radiotherapy. The accurate determination of the magnetic field by measurement is critical for the prediction of the particle beam trajectory and hence the design of the accelerator complex. In this context, state-of-the-art numerical field computation makes use of boundary-element methods (BEM) to express the magnetic field. This enables the accurate computation of higher-order partial derivatives and local expansions of magnetic potentials used in efficient numerical codes for particle tracking. In this paper, we present an approach to infer the boundary data of an indirect BEM formulation from magnetic field measurements by ensemble Kálmán filtering. In this way, measurement uncertainties can be propagated to the boundary data, magnetic field and potentials, and to the beam related quantities derived from particle tracking. We provide results obtained from real measurement data of a curved dipole magnet using a Hall probe mapper system.

Ultrasensitive optofluidic coupled Fabry-Perot capillary sensors.

Refractive index (RI) measurements are pertinent in concentration and biomolecular detection. Accordingly, an ultrasensitive optofluidic coupled Fabry-Perot (FP) capillary sensor based on the Vernier effect for RI sensing is proposed. Square capillaries integrated with the coupled FP microcavity provide multiple microfluidic channels while reducing the complexity of the fabrication process. The incoherent light source and spectrometer used during measurement facilitate the development of a low-cost sensing system. An ultrahigh RI sensitivity of 51709.0 nm/RIU and detection limit of 2.84 × 10-5 RIU are experimentally demonstrated, indicating acceptable RI sensing performance. The proposed sensor has significant potential for practical and low-cost applications such as RI, concentration, or biomolecular sensing.

Simple, Rapid Spectrophotometric Assay of Dispensed Methadone for Diversion Control.

Treatment of opioid use disorder with methadone is highly effective. Methadone is dispensed from opioid treatment programs under regulated circumstances. However, diversion of take-home doses can occur and is difficult to detect. We wanted to test the application of a handheld ultraviolet light absorption spectrometer to detect the concentration of methadone in take-home bottles that were suspected of being altered by the patient. Standardized dilutions of methadone hydrochloride oral concentrate were used to calibrate absorption wavelengths and then compared to take homes from suspected and unsuspected bottles to see if measured concentrations differed from expected doses. Ten standardized "control" doses were analyzed to determine 99% confidence intervals. These were compared to 104 samples "not-of-concern" obtained randomly over a 10-month period. An additional 103 methadone bottles of concern from 27 patients showed 15 bottles with &lt;25 % and 8 with &lt;75 % of expected concentrations. A handheld, low-cost ultraviolet light spectrometer detected altered take-home doses of methadone. This assay presents a simple and effective method for methadone clinics to perform inhouse analysis on "call back" methadone doses. It allows individual clinics to define diversion rates of their patient body, while allowing state and federal agencies to better understand how much prescribed methadone is diverted for illicit uses.

In-Field Wheat Reflectance: How to Reach the Organ Scale?

The reflectance of wheat crops provides information on their architecture or physiology. However, the methods currently used for close-range reflectance computation do not allow for the separation of the wheat canopy organs: the leaves and the ears. This study details a method to achieve high-throughput measurements of wheat reflectance at the organ scale. A nadir multispectral camera array and an incident light spectrometer were used to compute bi-directional reflectance factor (BRF) maps. Image thresholding and deep learning ear detection allowed for the segmentation of the ears and the leaves in the maps. The results showed that the BRF measured on reference targets was constant throughout the day but varied with the acquisition date. The wheat organ BRF was constant throughout the day in very cloudy conditions and with high sun altitudes but showed gradual variations in the morning under sunny or partially cloudy sky. As a consequence, measurements should be performed close to solar noon and the reference panel should be captured at the beginning and end of each field trip to correct the BRF. The method, with such precautions, was tested all throughout the wheat growing season on two varieties and various canopy architectures generated by a fertilization gradient. The method yielded consistent reflectance dynamics in all scenarios.

Optical Properties of Lentil Seed Coats Using Fiber-Optic Spectroscopy

HighlightsA fiber-optic spectroscopy system was set up and validated for measurement of optical properties of lentil seed coat.Light transmission properties of major lentil seed coat types were measured to evaluate their protective ability.Light transmission was detected mainly in the UVA and visible regions in all seed coat types except zero tannin.The protective abilities differed depending on seed coat type (important in breeding for cotyledon protection).Abstract. The light transmission of 20 lentil genotypes, representing six color classes (black, green, tan, brown grey, and zero tannin) was investigated to determine the degree to which seed coats prevent light transmission and possible photodegradation of cotyledon color. A fiber-optic spectroscopy system was set up for measurement; it consisted a deuterium-halogen light source, spectrometer, fiber-optic incidence and transmission probes, and sample holders. The nadir-aligned transmission spectra were measured in wavelength ranges of 250 to 850 nm. To study variability in light transmission of the different seed coat types, the curves were integrated in three wavelength regions to obtain Cumulative UV Transmission (CUVT, 250 to 400 nm), Cumulative VIS Transmission (CVIST, 401 to 700 nm), and Cumulative NIR Transmission (CNIRT, 701 to 850 nm), respectively. Tests for significant differences in light transmission were then done using analysis of variance (ANOVA) via General Linear Modelling and Posthoc GLM Tukey tests. Results showed that all the seed coat types, except zero tannin, showed no detectable transmission of UV light from 250 to 315 nm. Black seed coats showed detectable transmission from 615 to 850 nm, while other seed coat types transmitted varying percentages of light from 315 to 850 nm. The results of ANOVA showed that there were significant (p&amp;lt;0.05) differences in light transmission properties of the major seed coat types. Keywords: Fiber optics, Lentils, Light transmission, Pulse quality, Spectroscopy, Seed coat.

Using Combinatorial Inkjet Printing for Synthesis and Deposition of Metal Halide Perovskites in Wavelength‐Selective Photodetectors

Metal halide perovskites have received great attention in recent years, predominantly due to the high performance of perovskite solar cells. The versatility of the material, which allows the tunability of the bandgap, has led to its use in light‐emitting diodes, photo, and X‐ray detectors, among other optoelectronic device applications. Specifically in photodetectors, the tunability of the bandgap allows fabrication of spectrally selective devices. Utilizing a combinatorial inkjet printing approach, multiple perovskite compositions absorbing at specific wavelengths in a single printing step are fabricated. The drop‐on‐demand capabilities of inkjet printing enable the deposition of inks in a precise ratio to produce specific perovskite compositions in the printed thin film. By controlling the halide ratio in the compositions, a mixed halide gradient ranging from pure MAPbI3via MAPbBr3to MAPbCl3is produced. The tunability in the absorption onset from 410 to 790 nm is demonstrated, covering the whole visible spectrum, with a precision of 8 nm steps for MAPb(BrxCl1−x)3compositions. From this range of mixed halide perovskites, photodetectors which show spectral selectivity corresponding to the measured absorption onset are demonstrated, paving the way for use in a printed visible light spectrometer without the need for a dispersion element.

Plasma diagnostic systems and methods used on the stellarator TJ-II

The TJ-II is a heliac-type stellarator device with major radius of 1.5 m and averaged minor radius ⩽0.22 m that has been operated at CIEMAT, Madrid since 1998. Its full magnetic field is created by a system of poloidal, central, toroidal and vertical field coils, thus it possesses a fully 3-dimensional plasma structure and a bean-shaped plasma cross-section. Although this results in a complicated vacuum-vessel layout, it has excellent port access for diagnostics (96 portholes). During its initial operational phase, it was equipped with a limited set of essential diagnostics. Since then, a broad variety and large number of both passive and active diagnostics have been installed. The former include Hα monitors, light spectrometers, an electron cyclotron emission radiometer, X-ray filter monitors, neutral particle analysers, magnetic diagnostics, as well as cameras, among others, while the latter include various laser, atomic and ion beam based diagnostics, microwave probe beams, Langmuir probes plus impurity injection techniques. In this paper, after describing the TJ-II stellarator, its heating and fuelling systems, the diagnostic systems employed are outlined and discussed briefly here. Finally, results obtained with selected systems are highlighted.

Ternary organic photodiodes with spectral response from 300 to 1200 nm for spectrometer application

The light spectrometer is one of the most widely used optical instruments, allowing users to measure and analyze spectral components. However, to reach a broad spectral response range, most spectrometers have to combine a silicon photodiode with an additional photodiode to account for the limited operating wavelength range of each in isolation. Here, we developed organic photodiodes (OPDs) by combining a novel narrow-bandgap non-fullerene acceptor (COTIC-4Cl) with a polymer donor (PCE10) in the presence of PC71BM as the third component. The resulting device based on the ternary blended material showed a wide spectral response from 300 to 1200 nm, beyond the response range of the traditional silicon-based photodiode. Moreover, at the wavelength of 1100 nm, the resulting OPD exhibited a specific detectivity of 5 × 1012 Jones and a responsivity of 0.3 A W−1, with a cut-off frequency of >1 MHz and a linear dynamic range of >120 dB, among the best performances of OPDs. Of particular importance is that, as a proof-of-concept, the resulting ternary OPD was successfully utilized as the key component of a spectrometer to measure the absorption across 300–1200 nm. These results indicate the potential applications of the broadband response OPDs for next-generation spectrometers.

Parametric handheld optical probe (HOPE) for biological tissue characterization in the near-infrared spectral range

Various optical monitoring techniques across the visible and near-infrared spectral regions have been developed to assess tissue characteristics for a wide range of biomedical and health science applications. In this work, we designed a multimodal non-invasive optical probe that can provide information regarding live tissue metrics. The probe, 12 mm in diameter, consists of three separate small probes with different diameters. Each of the probes is sensitive to a different intrinsic tissue feature for diagnostic purposes. These features include diffuse light reflectance, scattering coefficient, refractive index, blood flow, and temperature. The probe apparatus is based on wideband light source and spectrometer, a laser Doppler flowmetry instrument, and a temperature-sensing device. The advantage of combining three different approaches in a single probe create a sensor able to characterize broad tissue metrics with high temporal resolution to better understand disease mechanisms. The performance of this hybrid handheld optical probe (HOPE) was tested in two models of tissue injury: (1) arterial occlusion of a human hand (n=3); and (2) brain hypoxia in mice (n=2). Following data analysis, differences in tissue parameters were observed compared to baseline measures. Experimental results illustrate the ability of the HOPE setup to monitor variations in different tissue parameters. This probe may serve as a sensor device for characterization of tissue features in a medical environment during clinical diagnosis and therapeutic procedures.