Wavelength Scanning Research Articles

A direct spectropolarimetric assay of arabinose 5-phosphate isomerase

Arabinose 5-phosphate isomerase (API) catalyzes the reversible isomerization of Ribulose 5-phosphate (Ru5P) to Arabinose 5-Phosphate (Ar5P) for the production of 3-deoxy-2-octulosonic acid 8-phosphate (KDO), a component of bacterial lipopolysaccharide (LPS) of gram-negative bacteria. API is an attractive target for therapeutic development against gram-negative bacterial pathogens. The current assay method of API activity utilizes a general reaction for keto sugar determination in a secondary, 3-h color development reaction with 25 N sulfuric acid which poses hazard to both personnel and instrumentation. We therefore aimed to develop a more user friendly assay of the enzyme. Since Ru5P absorbs in the UV region and contains at least 2 chiral centers, it can be expected to display circular dichroism (CD). A wavelength scan revealed indeed Ru5P displays a pronounced negative ellipticity of 30,560 mDeg M−1cm−1 at 279 nm in Tris buffer pH 9.1 but Ar5P does not have any CD. API enzymatic reactions were monitored directly and continuously in real time by following the disappearance of CD from the Ru5P substrate, or by the appearance of CD from Ar5P substrate. The CD signal at this wavelength was not affected by absorption of the enzyme protein or of small molecules, or turbidity of the solution. Common additives in protein and enzyme reaction mixtures such as detergents, metals, and 5% dimethylsulfoxide did not interfere with the CD signal. Assay reactions of 1–3 min consistently yielded reproducible results. Introduction of accessories in a spectropolarimeter will easily adapt this assay to high throughput format for screening thousands of small molecules as inhibitor candidates of API.

Cost-Effective Quasi-Parallel Sensing Instrumentation for Industrial Chemical Species Tomography

Chemical species tomography (CST) has been widely applied for the imaging of critical gas-phase parameters in industrial processes. To acquire high-fidelity images, CST is typically implemented by the line-of-sight wavelength modulation spectroscopy measurements from multiple laser beams. In this article, we present a novel quasi-parallel sensing technique and electronic circuits for industrial CST. Although the acquisition and processing of these multiple beams using a fully parallel data acquisition and signal processing system can achieve maximized temporal response in CST, it leads to a highly complex and power-consuming instrumentation with electronics-caused inconsistency between the sampled beams, in addition to a significant burden on data transfer infrastructure. To address these issues, the digitization and demodulation of the multibeam signals in the proposed quasi-parallel sensing technique are multiplexed over the high-frequency modulation within a wavelength scan. Our development not only maintains the temporal response of the fully parallel sensing scheme but also facilitates the cost-effective implementation of industrial CST with very low complexity and reduced load on data transfer compared with the fully parallel sensing technique. The proposed technique was analytically proofed and then numerically examined by noise-contaminated CST simulations. Finally, the designed electronics was experimentally validated using a lab-scale CST system with 32 laser beams.

HPLC Method for Simultaneous Determination of Dextromethorphan Hydrobromide, Chlorpheniramine Maleate and Potassium Sorbate in Cough Syrup

The development and validation of an analytical method for the simultaneous determination of Dextromethorphan Hydrobromide, Chlorpheniramine Maleate, and Potassium Sorbate in cough syrup using the High-Performance Liquid Chromatography (HPLC) method have been conducted. The determination was carried out on the simulation sample consisting of three substances and prepared five different concentrations, with three replications for each concentration. The optimum HPLC conditions were obtained using the C18 column, with UV detection at 230 nm The mobile phase of acetonitrile & phosphate buffer pH 2.5 (containing sodium-heptane sulfonate as ion-pair), with a gradient elution system, at a 1 mL/minute, while the flow rate column temperature is set at 35oC. The results showed that the method has met the parameters set in the validation test with the recovery ranged from 98% - 102%, the precision test results (RSD) < 2%, and the linearity (r) ≥ 0.98. The method obtained is quite selective by confirmed identity with the maximum wavelength scanning of each analyte peak by PDA detector. The limit of detection (LoD) for Dextromethorphan-HBr, Chlorpheniramine maleate and Potassium sorbate were 3.13 µg/mL, 0.94 µg/mL and 0.12 µg/mL respectively and the limit of quantitation (LoQ) were 9.49 µg/mL, 2.85 µg/mL and 0.38 µg/mL respectively.

Subaperture stitching wavelength scanning interferometry for 3D surface measurement of complex-shaped optics

Subaperture stitching wavelength scanning interferometry with a high-accuracy multi-axis position stage is proposed for measuring complex surface shapes such as aspherical and freeform optics. Typical optical approaches suffer due to poor fringe visibility when it comes to complex-shaped optics. Our proposed technique allows a proper solution to this challenging issue by keeping the optical probe perpendicular to the surface slope, which provides good fringe visibility during the wavelength scan regardless of how steep the surface is. Also, the full-aperture surface map of a test sample can be obtained by stitching multiple subaperture measurement results with high precision. We tested and verified our method by measuring several representative samples and comparing the measurement results with a well-established stylus method.

Development and Validation of Two Novel Chromatographic Methods: HPTLC and HPLC for Determination of Bromhexine Hydrochloride in Presence of Its Two Impurities.

Two simple, sensitive and validated chromatographic methods were developed for quantitative determination of bromhexine hydrochloride (BHX) in presence of its major impurities, impurity B (IMB) and impurity C (IMC), as specified by British Pharmacopoeia. First method (I) was high-performance thin layer chromatography-densitometry at which the chromatographic separation was performed using silica gel plates and developing system consisted of hexane:acetone:ammonia solution (9:0.5:0.08, by volume) with ultraviolet scanning at 240nm and linearity was achieved in the ranges of 0.40-10.00, 0.20-2.00 and 0.20-2.00μg/band of BHX, IMB and IMC, respectively. Also, second chromatographic method (II) was high-performance liquid chromatography (HPLC) where the separation was carried out on C18 column at isocratic mode at flow rate 1.5mL/min. The mobile phase consisted of methanol:water (90:10, v/v) adjusted to pH2.5 with O-phosphoric acid and temperature was adjusted to 40°C. The scanning wavelength was 240nm. The chromatographic run time was 6min. Linearity of this method was achieved in the ranges of 4.00-40.00, 0.20-10.00 and 0.50-10.00μg/mL for BHX, IMB and IMC, respectively. The validation of these chromatographic methods was made according to International Conference on Harmonization guidelines. These methods were successfully applied for determination of BHX in its pharmaceutical formulation. Also, statistical comparison was attained between the developed methods and the reported HPLC method using Student's t-test and F-test, and the obtained results showed that there was not any significant difference between them concerning with accuracy and precision.

Qualitative and quantitative analyses of labiatenic acid, apigenin and buddleoside in Hyssopus officinalis by high-performance thin-layer chromatography

This study involved qualitative and quantitative analyses of rosmarinic acid (synonym: labiatenic acid), apigenin and buddleoside by high-performance thin-layer chromatography (HPTLC). The thin-layer plate was a polyamide film and dichloromethane, ethyl acetate, and formic acid (6:5:1, V/V) were used as the mobile phase, spraying 2% aluminum trichloride ethanol solution, heating until the spots were clear; the scanning wavelength was 330 nm. The RF values of rosmarinic acid, apigenin and buddleoside were 0.20 ± 0.05, 0.36 ± 0.05 and 0.59 ± 0.05, respectively. The linear ranges of rosmarinic acid, apigenin and buddleoside were 0.0900‒0.4540 μg, 0.0328‒0.1968 μg and 0.02005‒0.1203 μg, respectively. The linear correlation coefficients were 0.9942, 0.9931 and 0.9904, respectively. The linear correlation coefficients were 0.9958, 0.9931 and 0.9928, respectively. The average recoveries of rosmarinic acid, apigenin and buddleoside were 101.29%, 99.75% and 100.8%, respectively, with RSD values of 1.81% (n = 6), 1.80% (n = 6) and 2.66% (n = 6), respectively. Thus, HPTLC proved to be a simple, accurate, and rapid qualitative and quantitative method. Therefore, the appropriate method should be selected according to the specific experimental conditions.

Nanobiocatalyst beds with Fenton process for removal of methylene blue

The remediation of methylene blue from wastewater using chitosan-sunflower-nano-iron (CSN) beds was examined in this study with the Fenton process. Nano-iron is synthesized using the green synthesis process. Then, biopolymer beds obtained nano-iron, sunflower tray waste, and chitosan. These beds used the Fenton process for removing Methylene blue (MB) from water. Beds synthesis and dye removing are characterized using SEM, TEM, FTIR, and XRD techniques. For the method optimization, the effects of dye concentration, temperature, pH, H2O2, and amount of biocatalyst were studied. The result of the wavelength scan was found 660 nm for methylene blue dye. Using CSN, catalyst was very effective in color removal for MB under optimal conditions. The highest removal rate 98% was obtained at pH 6 for 270 min. The optimum conditions for the MB dye are as follows; dye concentration: 25 mg/L, amount of absorbent: 2.5 mg/mL, temperature: 60 °C, H2O2 amount: 20 mg/L (600 µL, 30%). When the experiment is studied in optimum conditions, max. dye removal was calculated to be 98%. From SEM, TEM, XRD, and FTIR results, the change in the surface of the biocatalyst could be clearly observed. It is understood that the biocatalyst synthesized from the results we obtained easily removed a large amount of dye (MB).

Interferometric thickness measurement of glass plate by phase-shifting analysis using wavelength scanning with elimination of bias phase error

Phase-shifting fringe analysis using wavelength scanning has been broadly applied to the interferometric profiling of the thickness variation of glass plates. However, the nonlinear phase shifting can cause bias error during wavelength scanning. In this study, the bias error in the calculated phase was formulated by Taylor series expansion. Using the formulation, a novel 15-sample algorithm of a partially negative window was derived to enable compensation for the bias phase error. The new 15-sample algorithm was visualized by the algorithm polynomial on the complex plane and Fourier description in the frequency domain. The bias error suppression capability of the developed algorithm was examined by using the numerical simulation. Finally, the proposed algorithm was used in conjunction with a large-aperture Fizeau interferometer to examine the thickness variation of a glass parallel plate.

Measurement of uranium isotope ratio by laser ablation absorption spectroscopy

&lt;sec&gt;High precision measurement of uranium isotope ratio (&lt;sup&gt;235&lt;/sup&gt;U/&lt;sup&gt;238&lt;/sup&gt;U) has important application in the field of nuclear energy safety. In this paper, based on high sensitivity tunable absorption spectroscopy technology, combined with the sample processing method of pulsed laser ablation plasma, high-precision measurement of uranium &lt;sup&gt;235&lt;/sup&gt;U/&lt;sup&gt;238&lt;/sup&gt;U isotope ratio in solid material is realized. In the experimental measurement, transitions near 394.4884 nm/394.4930 nm (vacuum) are selected as the &lt;sup&gt;235&lt;/sup&gt;U/&lt;sup&gt;238&lt;/sup&gt;U analytical lines. The influence of buffer gas and its pressure on the persistence time of uranium atom in laser ablated plasma are studied in detail. &lt;/sec&gt;&lt;sec&gt; The experimental results show that different buffer gases have different ability to restrict the movement of particles in the plasma, which leads to different longitudinal expansion velocity of the plasma (perpendicular to the surface of the sample), and increases the persistence time of uranium atoms in the laser beam. The effect of pressure change on plasma evolution can be reduced by adding buffer gas. When helium is used as the buffer gas, the persistence time of uranium atoms in the plasma is longer, which can improve the selection space of data acquisition delay. In the ablation environment with helium, the electron number density of laser ablated plasma is relatively low, which can reduce the influence of Stark broadening effect and obtain narrower absorption lines, which is more conducive to the measurement of uranium atomic absorption spectrum. In order to reduce the influence of Doppler shift effect on absorption spectrum measurement and avoid misjudgment in spectrum analysis, it is more appropriate to carry out experimental measurement after 3μs sampling delay. Through experiments, the optimal conditions for measuring atomic absorption spectrum of uranium are obtained. Under these conditions, five different samples with &lt;sup&gt;235&lt;/sup&gt;U content of 4.95%, 4.10%, 3.00%, 1.10% and 0.25% respectively are measured, and the high-resolution absorption spectrum signals of &lt;sup&gt;235&lt;/sup&gt;U and &lt;sup&gt;238&lt;/sup&gt;U are obtained. The absorption spectra of samples with different content are measured and statistically analyzed, the &lt;sup&gt;235&lt;/sup&gt;U absorption signal has high linearity, the fitting correlation coefficient can reach 0.989, and the limit of detection is 0.033% (3σ). The stability test of absorption spectrum signal shows that the relative standard deviation of &lt;sup&gt;238&lt;/sup&gt;U, &lt;sup&gt;235&lt;/sup&gt;U and &lt;sup&gt;235&lt;/sup&gt;U / &lt;sup&gt;238&lt;/sup&gt;U signals are 2.054%, 2.152% and 0.524% respectively. The wavelength scanning mode is superior to the fixed wavelength spectrum measurement, and the influence of the energy fluctuation between different ablation pulses on the spectrum measurement is weakened by the wavelength scanning mode to a certain extent. The results show that laser ablation combined with absorption spectroscopy technology is suitable for uranium isotope ratio analysis and has great potential applications in rapid isotope analysis of nuclear fuel.&lt;/sec&gt;

Near-Infrared Fiber-Coupled Off-Axis Cavity-Enhanced Thermoelastic Spectroscopic Sensor System for In Situ Multipoint Ammonia Leak Monitoring

A near-infrared ammonia (NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) sensor system based on a novel fiber-coupled off-axis cavity-enhanced thermoelastic spectroscopy (OA-CETES) was demonstrated for the first time. A quartz tuning fork (QTF) with a high Q-factor of ~12 000 was served as a detector and placed after a 6-cm-long off-axis integrated cavity with a finesse of ~482. The proposed fiber-coupled scheme was adopted exploiting a 100-m-long single-mode and multimode optical fiber for long-distance and multipoint sensing. Dual-laser modulation schemes of wavelength scanning and locking were comparably used for performance improvement. By targeting the NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> line at 6612.71 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , the developed OA-CETES sensor achieved a minimum detection limit (MDL) of 8.5 parts per million (ppm) for a 100-ms integration time and a normalized noise equivalent absorption (NNEA) coefficient of 1.7×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> WHz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1/2</sup> . A fast-response NH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> leak monitoring with single-channel and multichannel cycling schemes was separately performed to verify the reliability of the proposed sensor system for field-sensing applications. The realization of the proposed OA-CETES with a small-size QTF (1-2 cm long) and fiber-coupled method allows a class of optical sensors for long-distance (up to kilometers) and multiplexed multipoint measurement and distributed sensing.

Quantification of Proton Radiation Damage in Polyimide Aerogel by Cantilever-Enhanced Photoacoustic Spectroscopy

Charged particles radiation induces the performances degradation of space polyimide (PI) aerogel, which puts forward the requirement for the accurate quantification of the radiation-induced damage. Photoacoustic spectroscopy (PAS) was proposed with a cantilever for the sensitive resonance detection of the photoacoustic (PA) pressure based on the analysis of cantilever-air dynamic coupling theory and finite element simulation. Wavelength scan PAS inspection of the proton irradiated PI aerogel verified the sensitivity of PA signals to the radiation fluence. Dual-wavelength PAS was first theoretically investigated and performed by measuring the PA signals alternately induced by the 405- and 532-nm lasers. Based on the presented theoretical relation between the PA signals and the radiation characteristics, the derived normalized damage fraction ( $f_{a}$ ) revealed distinct reliance on the proton fluence ( $\phi$ ). The experimental results and the theoretical relations fit well on the goodness of $\chi ^{2} = 8.2 \times 10^{-4}$ , and the fit value of the single-proton damage area ( $\sigma$ ) was $1.4\times 10^{-16}$ cm2. The relative error for the measurement of fluence ( $\phi$ ) was 5%. The research indicates that the presented cantilever-enhanced PAS method is an efficient tool for rapid and accurate quantification of the proton radiation-induced damage in PI aerogel.

Wavemeter Capable of Simultaneously Achieving Ultra-High Resolution and Broad Bandwidth by Using Rayleigh Speckle From Single Mode Fiber

Rayleigh speckle with random jagged pattern resulting from the interference of Rayleigh backscattering lightwave in a single-mode fiber contains the wavelength information of the incident lightwave. We propose an all-fiber wavemeter based on the relation between Rayleigh speckle and wavelength. The system does not suffer from the resolution-bandwidth trade-off relation and simultaneously achieves an ultra-high resolution of 40 attometers and a broad bandwidth of 80 nm covering 1520 to 1600 nm. The wavemeter could enable precise measurement of continuous-wave optical waveforms at time resolution of 100 μs. Combined with a dynamic laser, the system can be regarded as a high-resolution spectroscopy for absorption spectrum analysis. To demonstrate the broad applicability of the technique, we use a laser step-scanned over 80 nm to measure the spectral response of hydrogen cyanide absorption line, and use a continuous-wave laser to measure its nonlinear wavelength scan over 1 nm. The proposed all-fiber wavemeter provides great prospects for ultra-precise spectrum analysis with ultra-broad bandwidth and ultra-high resolution.

Ultrafast Surface Plasmon Resonance Imaging Sensor via the High-Precision Four-Parameter-Based Spectral Curve Readjusting Method.

A variety of surface plasmon resonance (SPR) sensing devices have been extensively used in biochemical detection for their characteristics of label-free, highly sensitive, and faster detecting. Among them, the spectrum-based SPR sensing devices have offered us great advantages in high-throughput sensing due to their large dynamic range and the possibility of detection resolution similar to that offered by angle interrogation. This paper demonstrates a spectrum-based SPR imaging sensing system with fast wavelength scanning capability achieved by an acousto-optic tunable filter (AOTF) and a low-cost and speckle-free halogen lamp implemented as the SPR excitation source. Especially, we developed a novel four-parameter-based spectral curve readjusting (4-PSCR) method for data processing, which offered us a faster and more accurate spectral data curve fitting process than the traditional polynomial fitting method. With the configuration, we have also conducted an SPR high-throughput detection of the novel coronavirus (COVID-19) spike protein, proving its application possibility in the screening of COVID-19 with high accuracy. We believe that the higher sensitivity and accuracy of the system have made it readily used in biochemical imaging and detecting applications.

Strong Coupling between Tamm and Surface Plasmons for Advanced Optical Bio-Sensing

The total internal reflection ellipsometry method was used to analyse the angular spectra of the hybrid Tamm and surface plasmon modes and to compare their results with those obtained using the conventional single SPR method. As such type of measurement is quite common in commercial SPR devices, more detailed attention was paid to the analysis of the p-polarization reflection intensity dependence. The conducted study showed that the presence of strong coupling in the hybrid plasmonic modes increases the sensitivity of the plasmonic-based sensors due to the reduced losses in the metal layer. The experimental results and analysis of the optical responses of three different plasmonic-based samples indicated that the optimized Tamm plasmons ΔRp(TP) and optimized surface plasmons ΔRp(SP) samples produce a response that is about five and six times greater than the conventional surface plasmon resonance ΔRp(SPR) in angular spectra. The sensitivity of the refractive index unit of the spectroscopic measurements for the optimized Tamm plasmon samples was 1.5 times higher than for conventional SPR, while for wavelength scanning, the SPR overcame the optimized TP by 1.5 times.

Imaging spectropolarimetry for magnetic field diagnostics in solar prominences

Context. Narrowband imaging spectropolarimetry is one of the most powerful tools available to infer information about the intensity and topology of the magnetic fields present in extended plasma structures in the solar atmosphere. Aims. We describe the instrumental set-up and the observing procedure that we have developed and optimized at the Istituto Ricerche Solari Locarno in order to perform imaging spectropolarimetry. A measurement that highlights the potential of the ensuing observations for magnetic field diagnostics in solar prominences is presented. Methods. Monochromatic images of solar prominences were obtained by combining a tunable narrowband filter, based on two Fabry-Perot etalons, with a Czerny-Turner spectrograph. Linear and circular polarization were measured at every pixel of the monochromatic image with the Zurich Imaging Polarimeter, ZIMPOL. A wavelength scan was performed across the profile of the considered spectral line. The HAZEL inversion code was applied to the observed Stokes profiles to infer a series of physical properties of the observed structure. Results. We carried out a spectropolarimetric observation of a prominence, consisting of a set of quasi-monochromatic images across the He I D3 line at 5876 Å in the four Stokes parameters. The map of observed Stokes profiles was inverted with HAZEL, finding magnetic fields with intensities between 15 and 30 G and directed along the spine of the prominence, which is in agreement with the results of previous works.

Distributed High Temperature Monitoring of SMF under Electrical Arc Discharges Based on OFDR.

The distributed high temperature measurement of an optical fiber subjected to electric arc discharges based on optical frequency-domain reflectometry is experimentally demonstrated. The distributed temperature profile is attained in an open glow regime of a few milliamps with maximum detectable temperature up to 2100 ± 20 °C. The discharge arc-induced softened length of the fiber and mechanical stress are measured and statistically analyzed in terms of the correlation of the Rayleigh spectra. The large wavelength scanning range of OFDR enables much higher accuracy for the delay time measurement with a minimum measured delay of 40 fs. The delay shift over the entire heating range for a single discharge duration is statistically calculated by using a temporal correlation method. The reliability of the thermal sensitivity coefficient as 10 pm/°C for telecom single mode fiber (SMF, @1550 nm) is quantitatively analyzed and evaluated by the correlation coefficient. Lastly, a spectral mapping method is employed in spectrum monitoring for discharge dynamic impact on the optical path length (OPL) and local Rayleigh scatter.

Near-GHz scanned-wavelength-modulation spectroscopy for MHz thermometry and H$$_2$$O measurements in aluminized fireballs of energetic materials

This manuscript presents the development of a two-color laser-absorption-spectroscopy (LAS) sensor capable of providing calibration-free measurements of temperature and H $$_2$$ O at 1 MHz in particle-laden combustion environments. This sensor employs scanned-wavelength-modulation spectroscopy with first-harmonic-normalized second-harmonic detection (scanned-WMS-2f/1f) with two distributed-feedback (DFB) tunable diode lasers (TDLs) emitting near 1392 nm and 1469 nm. The wavelength of each laser was modulated at 35 or 45.5 MHz to frequency multiplex the lasers and, more importantly, enable simultaneous wavelength scanning across the peak of each H $$_2$$ O absorption transition at 1 MHz. This method provides an absolute, in situ wavelength reference which improves measurement accuracy and robustness. Methods to characterize the lasers’ wavelength and intensity modulation at frequencies above 10 MHz are presented. Measurements of temperature and H $$_2$$ O mole fraction within 0.3–2.5% and 2–10%, respectively, of known values were acquired in a static-gas cell at temperatures of 700–1200 K. The sensor was applied to measure the path-integrated temperature and H $$_2$$ O column density in fireballs produced by igniting 0.75 g of grade 3, class B HMX with and without H-5 micro-aluminum powder (20% by mass). Temperature measurements were acquired in the fireballs with a 1– $$\sigma$$ precision of 50 K, 30 K, and 15 K for measurement rates of 1 MHz, 250 kHz, and 25 kHz, respectively. The results are the first to demonstrate that calibration-free measurements of gas properties can be acquired at 1 MHz using WMS-2f/1f.

Gas cell studies of thorium using filament dispensers at IGISOL

Filament-based dispensers of thorium have been investigated at the IGISOL facility, Jyväskylä, for potential use as a thorium ion source for future collinear laser spectroscopy experiments. Several different filaments were manufactured in the Institute of Atomic and Subatomic Physics of TU Wien, with 232Th and 229Th prepared on tantalum substrates either by drying thorium nitrate solution or via molecular plating, while adding a layer of zirconium for oxide reduction. The filaments were characterized in a helium-filled gas cell by performing selective and efficient in-gas-cell resonance laser ionization and by analyzing the resulting ion beams by mass spectrometry. Additionally, the in-gas-cell laser ionization process of thorium was further characterized by wavelength scans, saturation measurements and by recording the temporal behavior of extracted ion pulses. Although an ion source was successfully created with mass-separated intensities over 106 ions/s, the required high filament temperature resulted in significant contributions from interfering impurities and deterioration of the filament structure.

Analysis of temperature-induced spectral drift in the solar spectrometer driven by leadscrew and bar mechanism

A solar spectrometer is designed and developed, which uses a leadscrew and bar mechanism as the wavelength scanning mechanism, to achieve the accurate measurement of the solar spectrum in 170 nm–350 nm range. When measuring the standard spectrum of mercury lamp under laboratory conditions, there is a spectral drift due to temperature-induced deformation of the wavelength scanning mechanism. By using the finite element analysis method, the temperature sensitivity of each component in mechanism is analyzed. And then the linear superposition relationship between temperature rise and deformation is determined. Combined with the working principle of wavelength scanning mechanism, the corresponding relationship between temperature change and spectral drift is deduced.Spectral scanning and temperature monitoring were carried out simultaneously in instrument test to acquire temperature data of the wavelength scanning mechanism as it driving the gratings. Spectral drift was estimated according to the temperature variation and the maximum deviation between the predicted wavelength drift and the measured wavelength drift is 0.0016 nm, which is 6% of the measured wavelength. The experiment data validate the theoretical analysis results. The relationship between temperature change and spectral drift provides a theoretical reference for the correction of the measurement results and the thermal control of the instrument.

Simultaneous thickness variation and surface profiling of glass plates using Fizeau interferometer with elimination of offset phase error

Fringe analysis using phase modulation through wavelength scanning is extensively utilized for profiling the surface and thickness variation of glass plates. However, the nonlinearity of the phase-modulation error during wavelength scanning causes an offset error in the calculated phase. Therefore, in this research, two types of 19-frame phase-extraction formulas were derived for simultaneous profiling of the thickness variation and surface of a glass plate, focusing on eliminating the offset phase error. These new formulas were visualized in the frequency domain using the Fourier description. The ability of these formulas to eliminate the offset error was confirmed through numerical error analysis. Finally, the surface and thickness variation of a glass plate were simultaneously profiled using the large-aperture Fizeau interferometer and the new 19-frame formulas. The standard deviations obtained for thickness variation and surface profiling were 4.687 and 14.421 nm, respectively, which were lower than those obtained when using other phase-extraction formulas.