Sources Of Different Wavelengths Research Articles

Improving Multi-wavelength Overlay Measurement Time by the Development of Color-Mixing Light Source

This paper introduces an innovative approach to streamline the time-consuming process of multiple-wavelength measurement in semiconductor overlay metrology. To achieve this, a color-mixing light source was developed, which employed light sources of different wavelengths, each modulated with different sine wave frequencies. By aligning these sources and directing them simultaneously onto the test sample, we mixed all wavelength information into a single test signal. Leveraging the known modulation frequencies, we can accurately extract the amplitudes of each wavelength using a three-parameter sine wave fitting method. These amplitudes effectively represent the sought-after signal for each wavelength. A 4-wavelength mixed light source was developed to demonstrate this method's feasibility. Compared with the intensities received independently for each wavelength, the reconstructed amplitude error was below 5%. Finally, in the test of multiple-wavelength overlay measurement, the overlay difference between this and traditional methods was only 0.078nm. The experimental results confirm that this method enables a reduction in the measurement time for multiple wavelengths from 0.8sec to 0.2sec, i.e., a 75% reduction).

Fluorescence confocal microscopy for evaluation of fresh surgical specimens and consecutive tumor cell isolation in rare pediatric tumors.

Fluorescence confocal microscopy (FCM) is an optical technique that uses laser light sources of different wavelengths to generate real-time images of fresh, unfixed tissue specimens. FCM allows histological evaluation of fresh tissue samples without the associated cryo artifacts after frozen sectioning. The aim of this study was to prospectively evaluate pediatric tumor specimens and assess their suitability for fresh tumor sampling. In addition, we aimed to determine whether tumor cell isolation for stable cell culture is still feasible after FCM imaging. Pediatric tumor specimens were imaged using FCM. Tumor viability and suitability for tissue sampling were evaluated and compared with H&E staining after paraffin embedding. In addition, FCM-processed and non-FCM-processed tissue samples were sent for tumor cell isolation to evaluate possible effects after FCM processing. When comparing estimated tumor cell viability using FCM and H&E, we found good to excellent correlating estimates (intraclass correlation coefficient = 0.891, p < 0.001), as well as substantial agreement in whether the tissue appeared adequate for fresh tissue collection (κ = 0.762, p < 0.001). After FCM, seven out of eight samples yielded passable cell cultures, compared to eight out of eight for non-FCM processed samples. Our study suggests that the use of FCM in tumor sampling can increase the yield of suitable fresh tumor samples by identifying viable tumor areas and ensuring that sufficient tissue remains for diagnosis. Our study also provides first evidence that the isolation and growth of tumor cells in culture are not compromised by the FCM technique.

Fluorescence Confocal Microscopy Can Accelerate Diagnosis of Cervical Lymphadenopathy

Fluorescence confocal microscopy (FCM) is an optical technique that uses laser light sources of different wavelengths to generate real-time images of fresh, unfixed tissue specimens. Unlike conventional histologic evaluation methods, FCM is able to assess fresh tissue samples without the associated cryo artifacts typically observed after frozen sectioning. The purpose of this study was to evaluate the utility of FCM imaging in the differential diagnosis of cervical lymphadenopathy. Twenty-two cervical lymph node specimens from patients with lymphadenopathy of unknown origin were imaged by FCM. Two pathologists independently evaluated the scans for suspicion of malignancy and preliminary diagnosis. Malignancy was reliably excluded or confirmed by both pathologists with a sensitivity of 90.9% for pathologist 1 and 100% for pathologist 2. The specificity was 100% for both pathologists. For the preliminary diagnosis, almost perfect agreement with the final diagnosis was observed for both pathologists (κ = 0.94 for pathologist 1 and κ = 1.00 for pathologist 2). This is the first study to investigate lymph node specimens with different diagnoses, including lymphoma, using FCM. Our results indicate that differential diagnosis of lymph node specimens is feasible in FCM images, thus encouraging further exploration of FCM imaging in lymph node specimens to accelerate diagnosis and open the possibility of digitizing diagnosis on fresh, unfixed tissue.

Chromatic bleaching and fractionation effects on optically stimulated luminescent dosimeter reuse

AbstractBackgroundOptically stimulated luminescent dosimeters (OSLDs) can be bleached and reused, but questions remain about the effects of repeated bleaching and fractionation schedules on OSLD performance.PurposeThe aim of this study was to investigate how light sources with different wavelengths and different fractionation schemes affect the performance of reused OSLDs.MethodsOSLDs (N = 240) were irradiated on a cobalt‐60 beam in different step sizes until they reached an accumulated dose of 50 Gy. Between irradiations they were bleached using light sources of different wavelengths: the Imaging and Radiation Oncology Core (IROC) bleaching system (our control); monochromatic red, green, yellow, and blue lights; and a polychromatic white light. Sensitivity and linearity‐based correction factors were determined as a function of dose step‐size. The rate of signal removal from different light sources was characterized by sampling these OSLDs at various time points during their bleaching process. Relative doses were calculated according to the American Association of Physicists in Medicine Task Group‐191. Signal repopulation was investigated by irradiating OSLDs (N = 300) to various delivered doses of 2, 10, 20, 30, 40, and 50 Gy in a single fraction, bleached with one of the colors, and read over time. Fractionation effects were evaluated by irradiating OSLDs up to 30 Gy in different size steps. After reading, the OSLDs were bleached following IROC protocol. OSLDs (N = 40) received irradiations in 5, 10, 15, 30 Gy fractions until they had an accumulated dose of 30 Gy; The sensitivity response of these OSLDs was compared with reference OSLDs that had no accumulated dose.ResultsLight sources with polychromatic spectrums (IROC and white) bleached OSLDs faster than did sources with monochromatic spectra. Polychromatic light sources (white light and IROC system) provided the greatest dose stability for OSLDs that had larger amounts of accumulated dose. Signal repopulation was related to the choice of bleaching light source, timing of bleaching, and amount of accumulated dose. Changes to relative dosimetry were more pronounced in OSLDs that received larger fractions. At 5‐Gy fractions and above, all OSLDs had heightened sensitivity, with OSLDs exposed to 30‐Gy fractions being 6.4% more sensitive than reference dosimeters.ConclusionsThe choice of bleaching light plays a role in how fast an OSLD is bleached and how much accumulated dose an OSLD can be exposed to while maintaining stable signal sensitivity. We have expanded upon investigations into signal repopulation to show that bleaching light plays a role in the migration of deep traps to dosimetric traps after bleaching. Our research concludes that the bleaching light source and fractionation need to be considered when reusing OSLD.

General aerosol Sauter mean diameter measurement for spherical and non-spherical particles based on low-complexity scattering algorithm

Sauter mean diameter (SMD) is a key microphysical indicator in aerosol measurements that rely on optical-scattering-related methods. However, owing to the lacking clear definition of non-spherical SMD and the complexity of scattering calculations for non-spherical particles, existing SMD measurement methods are only applicable to spherical particles. A general SMD measurement method for both spherical and non-spherical aerosols is thus proposed. In this method, the shape coefficients of non-spherical particles are defined and used to calculate SMD. The scattering models for spherical and non-spherical particles are unified into a low-complexity scattering algorithm (LCSA). Based on LCSA, SMD can be measured using only two light sources of different wavelengths. Compared with SMD measurement results without considering particle shape, the accuracy of the proposed method increased by an average of 11.31% and 11.37% for unimodal and bimodal aerosols, respectively, while its accuracies for spherical and non-spherical aerosols respectively reached 95.26% and 93.43%.

Hollow-core anti-resonant fiber magnetic field sensor based on negative curvature Semi-Tubular

Magnetic field detection is critical for geological exploration in complex environments. Based on the principle of leaky mode resonance (LMR), a semi-tubular hollow-core anti-resonant fiber (HC-ARF) filled with a magnetic fluid (MF) is proposed for magnetic field sensing in this study. When the semi-tubular air cladding cavity is filled with MF, a Fabry–Perot (F-P) resonator can be formed between the MF and the silica cladding, and the negative-curvature semi-tubular structure can confine the light in the fiber core. Different magnetic field strengths vary the reflectivity and resonance conditions of the F-P resonator, which in turn affect the resonance wavelength and transmittance. The results show that the sensitivity of the wavelength shift can reach 68.39 pm/Oe for magnetic field strengths in the range of 60–180 Oe. This HC-ARF magnetic field sensor can realize magnetic field detection under light sources of different wavelengths according to the selection of the resonance order. The sensor exhibits a low loss, wide bandwidth, and high sensitivity, and thus it has good development prospects for geological exploration.

A Systematic Study of Laser‐Engineered Fluorescence in Carbon Black

The feasibility of laser-engineered fluorescence emission from carbon black (CB) with three laser sources of different wavelengths—660 nm (red), 532 nm (green), and 405 nm (blue) is demonstrated. From which the 660 nm focused laser beam produces the most intense fluorescence. Detailed systematic studies on how the laser-engineered fluorescence emission from CB depends on laser power, laser patterning speed, and environmental control during the laser modification process are carried out. From the systematic studies, the CB samples in ambience undergo most noticeable modifications with a laser power of ≈7 mW and patterning speed of ≈12 μms−1. The fluorescence emission is attributed to the creation of complex defects states into the oxidized form of the pristine system by the formation of 1) C60 fullerene and fullerites; 2) ZnO; 3) Zn2SiO4, and more complex hybrid such as 4) carbon-induced mid-gap states in Zn2SiO4, and 5) Ca-induced defects in ZnO. Such incorporations resulted in the formation of intermediate states in the large bandgap materials. As a result, distinct multicolored fluorescence is emitted by these laser-quenched material systems. Accordingly, multicolored fluorescence designs can be created with elaborative control of focused laser treatment in an ambient and helium environment.

Light quality and natural ventilation have different effects on protocorm development and plantlet growth stages of the in vitro propagation of Epidendrum fulgens (Orchidaceae)

Improvements of in vitro culture protocols are essential to increase productivity in order to ensure their practical application in commercial laboratories. The aim of the present work was to evaluate the influence of light sources of different wavelengths in combination with natural ventilation of the in vitro atmosphere (NV) in all steps of the micropropagation, from the seed germination and protocorm development (SGS) to plantlet growth (PGS), as well as for ex vitro acclimatization. Additionally, we compared the use of a temporary immersion bioreactor (Plantform™) and NV for the PGS. We evaluated the parameter effects on the velocity of development of protocorms, and the productivity and quality of plantlets, accessing both morphological and biochemical features, as velamen formation, stomatal functionality, photosynthetic pigments and microscopic features. For SGS, NV was detrimental. W and DR. LED lights accelerated protocorm development, while fluorescent light increased their fresh weight. For PGS, NV was responsible not only to enhance fresh weight and root number, but also stimulated the development of velamen and the functionality of stomata. NV also increased photosynthetic pigment concentration and sclerenchyma formation in leaves. Plantform™ increased the fresh weight, the number of organs, and leaves had thicker cuticles.

Influence of Light Sources of Different Wavelengths on Scattering Rate of Defects

Influence of Light Sources of Different Wavelengths on Scattering Rate of Defects

Heterodyne Standing-Wave Interferometer with Improved Phase Stability

This paper describes a standing-wave interferometer with two laser sources of different wavelengths, diametrically opposed and emitting towards each other. The resulting standing wave has an intensity profile which is moving with a constant velocity, and is directly detected inside the laser beam by two thin and transparent photo sensors. The first sensor is at a fixed position, serving as a phase reference for the second one which is moved along the optical axis, resulting in a frequency shift, proportional to the velocity. The phase difference between both sensors is evaluated for the purpose of interferometric length measurements.

Effect of TiO2 layer thickness of TiO2/NiO transparent photovoltaics

AbstractThe rapid growth in the transparent electronics industry has increased the need for transparent photovoltaic cells (TPCs) and transparent self‐powered devices. To make TPCs and transparent self‐powered devices more efficient, a detailed understanding of device structure is needed. In this study, TiO2/NiO heterojunction‐based TPCs were fabricated with different TiO2 layer thicknesses, and the effect of TiO2 layer thickness on the photovoltage and photocurrent was evaluated. All the fabricated TiO2/NiO heterojunction‐based devices had a high optical transparency (&gt;50%) in the visible–near‐infrared (vis–NIR) region. The fabricated devices were illuminated with different power sources of different wavelengths. If the TiO2 layer was too thick or too thin, the TPC performance deteriorated. By growing the optimal 100‐nm‐thick TiO2 layer, a simultaneous tunability between high optical transparency and high photovoltaic performance was achieved. A TiO2/NiO heterojunction‐based device with an optimal 100‐nm‐thick TiO2 layer had the highest optical transparency (&gt;60%) in the vis–NIR region, with the highest photovoltage of 685.00 ± 68.06 mV and the highest photocurrent of 4.42 ± 1.35 mA under the illumination of a light source with a power density of 70 mW/cm2 at a wavelength of 365 nm. The fabricated TPCs had a high sensitivity to ultraviolet (UV) signals and demonstrated self‐powered behavior. This study clarified the role of TiO2 layer thickness optimization in improving the performance of TiO2/NiO heterojunction‐based TPCs.

A new method for measuring pen pressure in forensic handwriting analysis – a proof of concept study

This work describes a new method for the analysis of handwritten documents through a system composed of a pre-selector optical analyser equipped with light sources of different wavelengths coupled with bandpass filters combined with an optical coherence tomography (OCT) instrument. The optical analyser identifies regions with different pen pressures on the paper using specific wavelengths from ultraviolet (UV) to infrared (IR) and bandpass filters. Then the selected regions are analysed with a coherence tomography analyser to measure the depth of grooves and capture three-dimensional images. With this methodology, it is possible to identify similarities, or differences, between the pieces of evidence under investigation, increasing the possibility of correct attribution concerning the authorship of the signature and we also showed that this feature is independent of the paper substrate. In this work, a new strategy will be presented to categorize and quantify pen pressure in order to aid a better response for a forensic examiner. Thereby, from the observed areas that display higher pressures (more significant grooves), it is possible to determine the authorship of the signature.

Differential Fiber Optic Gyroscope Driven by Two Broadband Sources of Different Wavelengths

We propose a differential fiber optic gyroscope driven by two broadband light sources with different wavelengths. Preliminary experiments demonstrate that both bias drift and angle random walk can be reduced considerably due to common-mode error cancellation. Theoretical analysis shows that the effect of transient temperature could be eliminated by optimizing the dispersion of the fiber coil and/or by introducing a dispersion compensation factor before taking the differential operation. Experiments with a fiber coil with weak wavelength-dependent dispersion coefficient show that significant reduction of bias drift due to transient temperature can be achieved with a proper dispersion compensation factor.

Laser-induced self-organization in Se–Te–Sn–Cd glassy semiconductor for developing novel light-sensing dielectrics

The laser-induced effects on dielectric properties of chalcogenide glass (ChGs) have been present in a glassy system of Se–Te–Sn–Cd for possible applications in optics and optoelectronics such as light-controlled capacitance-based touch displays. The temperature/frequency dependence of dielectric relaxation before and after laser exposure was investigated by using laser sources of different wavelengths (405 nm, 532 nm, 690 nm, and 785 nm). The result showed the presence of laser-induced residual effects on dielectric properties (dielectric constant/loss and a.c. conductivity) after the exposure of continuous-wave laser sources of chosen wavelengths. Further analysis indicates that the modification in the meta-stable state due to self-organization is the feasible mechanism of observed persistent light-sensing effects.

Optothermal properties of a converter of laser radiation to the radiation of a high-temperature point source

Laser radiation sources of different wavelengths with a silica fiber output are widely used in engineering (surface clearing and scratching/engraving, and so on) and in medicine (effective low-invasive scalpels for treating various diseases). These applications are based primarily on direct exposure of the object to laser radiation. The properties of a converter of such a laser radiation to the radiation of a point (∼0.5 · 0.5 mm), high-temperature (∼2000 K) source with strongly absorbing coating (SAC) at the distal end of the silica fiber are considered in the presented work. The use of a converter expands the capabilities of laser instruments significantly. The temperature (∼2000 K) of the operating silica fiber tip with SAC at a laser pump power of 3–10 W (λ = 1.47 μm) and its time dependence in air atmosphere, in CO2 gas and in vacuum have been studied in experiment. The results of the studies and the physical properties of heat transfer and material stability in the converter design are considered. Recommendations on converter application as a scalpel with SAC for cutting soft and hard biological tissues are formulated.

Heterodyne standing-wave interferometer / Heterodynes Stehende-Welle-Interferometer

Abstract This manuscript describes a novel standingwave arrangement with two laser sources of different wavelengths, emitting towards each other. The resulting standing wave has a continuously moving intensity profile, a thin, transparent photo sensor is inserted into. When the sensor is moved along the optical axis a frequency shift, proportional to the velocity, occurs. This frequency shift can be evaluated for the purpose of interferometric length measurements.

Ultraviolet Sensor Performance of Nanostructured LaCoO3 Prepared By Solution-Polymerization Method

LaCoO3 has been extensively studied for their outstanding physical and chemical properties, which have applications in fields like heterogeneous catalysis, solid oxide fuel cells (SOFC’s), gas permeation membranes and gas sensors, to name a few [1,2]. LaCoO3 is a p-type semiconductor material, possessing the perovskite-type structure and has a band gap of 2.2 eV [3]. In this work, the detection of ultraviolet light (UV), as well as other light sources of different wave lengths (λ), was investigated for this oxide. For this purpose, polycrystalline LaCoO3 was synthesized by the solution-polymerization method, using an aqueous solution containing La and Co nitrates and polyvinyl alcohol. The identification of single-phase LaCoO3 was made by X-ray powder diffraction on samples calcined at 700ºC, in air. The surface microstructure was observed by field emission scanning electron microscopy, showing abundant porous sheets formed by networks of interconnected nanoparticles. Images obtained by transmission electron microscopy indicate that LaCoO3 crystallites have an average size of 50 nm. Measurements for detecting UV and light in the visible region were done at room temperature, using light emitting diodes (LEDs) of different λ and optical irradiances (Ee). The latter were done on LaCoO3 thick films prepared by depositing a suspension of the as-prepared powder on alumina substrates, with silver wires as electrodes. A typical graph showing the variation of the electrical resistance (R) with time, caused by the exposure of LaCoO3 to UV radiation (λ = 365 nm, Ee = 217 mW/cm2) and darkness, can be observed in Fig. 1. The results show a uniform response pattern, characterized by a decrease of resistance under UV light. The quantitative detection of UV radiation was also evaluated by varying the optical irradiance from 22 to 217 mW/cm2. The results indicate a non linear relationship between R and Ee, tending to a constant value while increasing Ee. I–V curves were also performed on LaCoO3 films confirming the latter results. For other light sources such as blue (λ = 449 nm), red (642 nm) and infrared (843 nm) reliable responses were also observed, noting that the change of R decreased by increasing λ. The results indicate that nanostructured LaCoO3 can be used as a wearable detector for UV radiation and a as sensitive material for photocells, among others. Even though this work was focused on UV detection, a good performance using light of larger λ was observed.

Effect of variation of thickness of TiO2 on the photovoltaic performance of n-TiO2/p-Si heterostructure

Fabrication of heterojunctions of Si along with oxide based semiconductors like TiO2 is an alternative method to produce cost effective solar cells. To study the photovoltaic performance of the n-TiO2/p-Si heterostructure, TiO2 thin films of different thicknesses were deposited on p type Si substrates using pulsed laser deposition technique. All the films were characterized using XRD, AFM, Spectroscopic ellipsometry and I–V characteristics with solar simulator and other monochromatic light sources of different wavelengths. Optical properties of the thin films were correlated with the I–V characteristics under dark and illumination conditions. It has been shown that thickness plays a crucial role on the photovoltaic performance of the n-TiO2/p-Si heterostructure. Further, it has been observed that the optical reflectivity of TiO2 thin film of particular optimized thickness deposited on p type Si could be lowest. Consequently, photocurrent of the n-TiO2/p-Si heterostructure is found to decrease with an increment of the thickness of the TiO2 thin film. This is attributed to the increment of series and sheet resistance with increase of TiO2 film thickness. Moreover, increase of TiO2 film thickness can also create surface states and defects in the n-TiO2/p-Si heterojunction which are also responsible for poor efficiency of the photovoltaic cells.

Photometric Absorbance Spectrum Analyzer of Slightly Transparent Biomaterials

Introduction. The measurement of optical radiation, especially the intensity of the light flux passing through biological tissues or other slightly transparent (cloudy) materials and the environments is a challenging problem due to the extensive development of new light sources of different wavelengths and their use in various fields of human activity. It is important to provide high sensitivity and accuracy measurement of the output parameters of light fluxes passing through the studied material - the depth of penetration, attenuation coefficient or absorption. The known methods and devices do not provide the required sensitivity and accuracy of measuring parameters. Main body. The aim of this study is to develop a photometric spectrum analyzer where along with the simplification of the scheme and increasing sensitivity and measurement accuracy the score of penetration depth of light flux into biological or other slightly transparent material, the determination of the attenuation coefficient and the spectrogram construction based on the analysis of two signals separated by wavelength light sources is ensured. One of the ways to increase the sensitivity and accuracy of the measurement devices is to use modulating method of the output signals transformation. Implementation of this method provides a significant reduction of the proper noises of the transformation signal path. Figure 1 shows a functional diagram of the developed by the authors device based on modulating transformation of the optical signal. It provides the measurement of the slightly transparent materials absorbance with increasing sensitivity and accuracy. Conclusions. Considered possibilities greatly simplify the measurement process. The use of the modulating transformation of the light flux provides increase in sensitivity in the measurement accuracy because such transformation compensates the intrinsic noise level and noise of the measurement channel. The semiconductor matrix is used as the light source. It provides accommodation of two crystals at one point of light diodes with the most spaced wavelengths allowing them to be placed on the same axis with photocell and excludes collateral scattering of the light flux.

Tunable photoluminescence properties of Pr3+/Er3+-doped 0.93Bi0.5Na0.5TiO3–0.07BaTiO3 low-temperature sintered multifunctional ceramics

Pr3+/Er3+-doped 0.93Bi0.5Na0.5TiO3–0.07BaTiO3 ceramics have been fabricated at a low sintering temperature of 960°C using a sintering aid of Li2CO3. The effects of energy transfer between Pr3+and Er3+on their photoluminescence properties have been investigated. Our results reveal that the down-conversion emissions of Pr3+are weakened and the lifetimes are shortened by the co-doping of Er3+. As a result, when both Pr3+and Er3+are excited simultaneously, with increasing the concentration of Er3+, the green emissions from Er3+increase but the red emissions from Pr3+decrease. Moreover, the emission color of the ceramics can be reversibly changed between red, yellow and yellowish green by using excitation sources of different wavelengths. Strong up-conversion green emissions with short lifetimes arisen from Er3+have also been observed for the ceramics under the excitation of 980nm. Owing to the Li2CO3 sintering aid, the low-temperature sintered ceramics also exhibit reasonably good ferroelectric and piezoelectric properties, and hence should be promising for multifunctional applications such as electro-optical coupling devices.