Glass Prism Research Articles

A Continuous Liquid-Level Sensor for Fuel Tanks Based on Surface Plasmon Resonance.

A standard problem in large tanks at oil refineries and petrol stations is that water and fuel usually occupy the same tank. This is undesirable and causes problems such as corrosion in the tanks. Normally, the water level in tanks is unknown, with the problems that this entails. We propose herein a method based on surface plasmon resonance (SPR) to detect in real time the interfaces in a tank which can simultaneously contain water, gasoline (or diesel) and air. The plasmonic sensor is composed of a hemispherical glass prism, a magnesium fluoride layer, and a gold layer. We have optimized the structural parameters of the sensor from the theoretical modeling of the reflectance curve. The sensor detects water-fuel and fuel-air interfaces and measures the level of each liquid in real time. This sensor is recommended for inflammable liquids because inside the tank there are no electrical or electronic signals which could cause explosions. The sensor proposed has a sensitivity of between 1.2 and 3.5 RIU−1 and a resolution of between 5.7 × 10−4 and 16.5 × 10−4 RIU.

III-V nitrides and performance of graphene on copper plasmonic biosensor

In the present study, the influence of iii-v nitrides as well as Ge and Si on the sensitivity and performance of a graphene protected copper plasmonic biosensor has been investigated. These semiconductors have been used between copper (Cu) and graphene layers on a SF 10 glass prism. The sensitivity and performance of the biosensor has been computed for with and without semiconductors. III-V nitrides demonstrated high sensitivity and high figure of merit (FOM) in comparison to Si and Ge due to their superior electronic and optical properties. The enhancement of evanescent electric field due to Si, Ge, AlN, GaN and InN have been computed and found highest enhancement for InN. This happens due to high refractive index of InN than other semiconductors. Analysis shows that for a high sensitive imaging biosensor the required optimal thickness of copper, InN and graphene are respectively 32 nm, 13 nm and 0.34 nm for light of wavelength λ = 633 nm (red HeNe laser). This study suggests that InN would be a better choice for fabrication of new imaging plasmonic biosensors for chemical and biological sensing.

Effect of ion beam irradiation on dielectric properties of BaTiO3 thin film using surface plasmon resonance

The effects of swift heavy ions on the structure, surface morphology and dielectric behaviour of barium titanate (BaTiO3, known as BTO) thin films have been investigated by irradiating the films with 100 MeV Au+8 ions at an ion fluence of 1 × 1012 ions cm−2. BTO thin films were deposited on Pt/Si substrate by pulsed laser deposition technique. The structure of the film was crystalline with tetragonal phase. Surface topography was studied by atomic force microscope. The dielectric properties of BTO have been studied using surface plasmon resonance (SPR) technique in Otto configuration. SPR is a highly sensitive technique for investigating the dielectric and optical properties of dielectrics. Gold-coated glass prisms have been utilized to excite the surface plasmon waves (SPWs) at the metal–air interface. When BTO thin film is integrated with the surface of Au thin film, a significant shift in the SPR curve has been observed due to change in the propagation constant of SPW at metal–dielectric interface. The optical and dielectric parameters of BTO thin film were obtained by fitting the experimental SPR data with the Fresnel’s equations. The observed increase in the dielectric constant of BTO thin film after irradiation may be attributed to packing density.

Dielectric dispersion of rf Sputter-deposited SnO<sub>2</sub>, ZnO, WO<sub>3</sub> thin films using surface plasmon resonance technique

Surface Plasmon Resonance (SPR) is a highly sensitive technique for investigating the dielectric and optical properties of dielectrics at metal-dielectric interface. In the present article, the dielectric properties of various wide band gap (WBG) semiconductor have been studied using SPR technique at different wavelengths. The metal oxide thin films of interest are tungsten oxide (WO3), tin oxide (SnO2) and zinc oxide (ZnO) which were deposited by rf magnetron sputtering under optimized growth conditions. Gold coated glass prisms have been utlilized to excite the surface plasmon waves at the metal-dielectric (air) interface. When metal oxide thin films are integrated with the surface of metal thin film, a significant shift in the SPR curve has been observed due to change in the propagation constant of Surface Plasmon Wave (SPW) at metal-dielectric interface. The optical and dielectric parameters of WBG thin films were estimated by fitting experimental SPR data with the Fresnel's equations. SPR reflectance curves obtained using laser of various wavelengths were ultilized to determine the wavelength dispersion of the dielectric properties of these metal oxide thin films.

Detection of Neisseria meningitidis using surface plasmon resonance based DNA biosensor

Herein, we report the development of a surface plasmon resonance (SPR) based biosensor for the detection of Neisseria meningitidis DNA employing Kretschmann configuration. Highly c-axis oriented ZnO thin film of thickness 200nm was deposited on gold coated glass prisms by RF sputtering technique. Single stranded probe DNA was immobilized on the surface of ZnO thin film by physical adsorption method. SPR reflectance curves were recorded as a function of incident angle of He–Ne laser beam using a laboratory assembled SPR setup. The prepared biosensor exhibits a linear response towards target meningitidis DNA over the concentration range from 10 to 180ng/μl with a high sensitivity of about 0.03°/(ng/μl) and a low limit of detection of 5ng/μl. The SPR biosensor demonstrated high specificity and long shelf life thus, pointing towards a promising application in the field of meningitidis diagnosis.

Geometrical-optics analysis of reflective glass beads applied to building coatings

Replacing highly reflective envelope materials, retro-reflective materials (RRMs) used as building coatings can help to fight the urban heat island effect. The common component of RRMs are mainly glass beads and prisms. The use of glass beads is relatively wider. This paper presents a study on the reflective principle of a single glass bead. Retro-reflective directional characteristics of a glass bead were evaluated by simulation. It showed that the reflective directional characteristics of glass beads are different for different refractive index of glass beads. Among the 3 refractive indexes evaluated, the retro-reflective directional characteristics of glass beads are the most remarkable when the index is 1.93. Compared to the refractive index of 1.93, both a lower refractive index and a higher refractive index have a much wider reflective distribution on the glass bead surface. The reflective directional properties are affected by the refractive index of the glass bead, but almost unaffected by the angle and direction of the incident light.

Effect of prism index on sensitivity of lossy mode resonance sensors operating in visible region

We present the theoretical results of the optimization of lossy mode resonance sensors at visible wavelengths. Both angular and spectral interrogations are carried out for absorbing indium tin oxide (ITO) films placed on glass prism. The inclusion of a low-index layer between the prism and the lossy (ITO) layer can produce an efficient refractive index sensor for bio/chemical applications. Further increase in sensitivity can be achieved by changing the index of the prism. It is shown that the sensitivity has strong dependence on the index of prism. Sensitivities as high as 4670 nm/RIU for spectral mode and 67 deg/RIU for angular mode with small values of full width at half maximum (FWHM) can be achieved. Dependence of sensitivity and FWHM on refractive index and thickness of low-index matching layer is also investigated.

Experimental demonstration of lossy mode and surface plasmon resonance generation with Kretschmann configuration

Lossy mode resonances (LMRs) and surface plasmon resonaces (SPRs) are obtained experimentally with a Kretschmann configuration using a BK7 glass prism with all sides polished and coated with indium tin oxide (ITO). The properties of ITO allow for obtaining LMRs and SPRs with the same experimental setup. The results are corroborated with a numerical method for calculation of the reflection in the Kretschmann configuration.

Novel optical current sensor for metering and protection in high power applications

ABSTRACTA clamp-on optical current sensor prototype for metering and protection applications in high power systems was developed and characterized. The system is based on the Faraday effect in a low birefringence, high Verdet constant, 8 cm long SF57 Schott glass prism. It was incorporated in a nylon casing suitable for clamp-on applications in the power line. The sensor operation was tested at 630 nm, 830 nm, and 1550 nm to access its applicability in remote interrogation via fiber links. Optimal operation at 830 nm is reported with a linear response up to 65.28kA, with 0.1 or 0.2 accuracy class considering a nominal currents of 1.2 and 0.3 kA (root mean square), respectively. Twelve calibrations procedures performed over six days showed an estimated maximum error of 11 m A. Preliminary measurements were made from 40 to 400 Hz. The sensor was exposed to transient signals less than 10 µs that demonstrated its use in protection applications.

Artificial halos

Judged by their frequency and beauty, ice halos easily rival rainbows as a prominent atmospheric optics phenomenon. This article presents experimental halo demonstrations of varying complexity. Using a single commercially available hexagonal glass prism, a variety of artificial halos can be simulated. The experiments include laser beam path analysis, a modified classic spinning prism experiment, and a novel Monte-Carlo machine for three-dimensional rotations. Each of these experiments emulates different conditions of certain halo displays, and in combination, they allow a thorough understanding of these striking phenomena.

STM-induced light emission from vacuum-evaporated gold film

A vacuum evaporation system has been used to evaporate gold film on glass substrate in order to probe the scanning tunneling microscope-light emission (STM-LE) from the evaporated film. The surface morphology of the evaporated Au film has been checked by atomic force microscope (AFM). In order to estimate the appropriate thickness of the Au film, which is essential for the enhancement of STM-LE in the prism-coupled geometry, a theoretical calculation has been performed. Our theoretical simulation revealed that the light emission from the prism-coupled STM junction is strongly enhanced when the Au film has a thickness of 40 nm. AFM observation also showed that the morphology of the gold films strongly depends on the cleanliness of glass substrates and the deposition temperature. Relatively smooth surface was observed when a 40-nm-thick Au film was evaporated at room temperature on the preannealed glass substrate. Finally, the evaporated films were deposited on the flat bottom of a hemispherical glass prism, and STM-LE from the tip–sample gap into the vacuum (tip-side emission) and into the prism (prism-side emission) were measured. It was found from the experimental results that the prism-side emission is much stronger than the tip-side emission by virtue of the enhancement of the prism-coupled geometry.

(i – δ) curve of a prism in ray optics in the light of the refined unambiguous angles of incidence and refraction

This paper makes use of the unambiguous definitions of angles of incidence and refraction offered by the author in 2005 to make an extensive study of the theoretical behavior of the (i – δ) curve of a prism in ray optics. Novel relations have been achieved for the explicit dependence of the final angle of emergence (i2) as well as the net deviation (δ) on the unambiguous primary angle of incidence (i1). Considering a glass prism with angle, A=60° and refractive index, μ=1.5, the theoretical relations developed have been subsequently employed to predict the graphical behavior of each of the (i1 versus i2) curve, (i1 versus (i2−i1)) curve, and (i1 versus δ) curve. Though the quantitative interpretation of the peculiar nature of the (i1 versus δ) curve of a prism follows from the relevant relation derived in the paper, qualitative interpretation regarding the peculiar trend of variation of the net deviation (δ) with the unambiguous primary angle of incidence (i1) has also been provided on the basis of the (i1 versus i2) as well as (i1 versus (i2−i1)) curves.

Intensity distribution of the parhelic circle and embedded parhelia at zero solar elevation: theory and experiments.

We describe the individual contributions to the intensity distribution of the parhelic circle for plate-oriented hexagonal crystals at exactly zero solar elevation using geometrical optics. An experimental as well as theoretical study of in-plane ray paths provides details on the mechanism for several halos, including the parhelia, the 120° and 90° parhelia, a blue edge, and the Liljequist parhelia. Azimuthal coordinates for associated characteristic features in the intensity distribution are compared with experimental data obtained using a spinning hexagonal glass prism.

Sensitivity Parameter Analysis of Graphene Based Bimetallic Surface Plasmon Resonance Biosensor

In this paper, we have studied theoretically the effect of bimetallic silver/ gold layer on sensitivity of the graphene based surface plasmon resonance (SPR) biosensor. Here, silver layer (instead of chromium and titanium) is used as an adhesive layer in between gold and BK7 glass prism. The optimized thickness of silver/gold layers reported in literature has been used for the analysis of various sensitivity parameters of the biosensor. A computational simulation is performed to analyze the nature of plasmon dip shift with respect to the addition of graphene layer and binding layer respectively.

Light and Optics. Frontiers in light & optics. Introduction.

![Figure][1] Glass prisms like the one shown here (reputedly owned by Isaac Newton and now in the collection of the Whipple Museum of the History of Science, University of Cambridge) were used to split white light into its constituent colors. PHOTO: © JOE MCNALLY. PHOTOGRAPHED AT THE

Development of Electrochemical and Optical Based Biosensors

During recent years, rapid and highly selective determination of nucleic acid (in particularly, DNA) has gained much importance in the field of disease diagnostics, gene analysis, tissue matching, forensic and environmental protection. Various techniques have been employed for DNA detection like fluorescence, surface plasmon resonance (SPR), quartz crystal microbalance (QCM), piezoelectric, electroluminiscene, and electro-chemical. Among all these techniques, electro chemical and SPR based biosensors for nucleic acid detection have attracted researchers worldwide due to their high sensitivity, low detection limit, fast response time, wide detection range, good reliability, easy handling and portability. DNA based biosensors rely on the immobilization of a single-stranded oligonucleotide probe onto a surface to recognize by hybridization its complementary target sequence. The probes are typically short oligonucleotides that are capable of hybridizing with specific and unique regions of the target nucleotide sequence. Due to formation of double helical structure between complementary strands, a change in current or SPR angle could be easily observed. In the present study, an effort has been made towards the development of ZnO matrix based biosensors for the detection of Meningitidis using electrochemical (Amperometric) and SPR techniques. The surface plasmon modes have been excited at the ZnO-gold interface in the Kretschmann configuration using a right angled BK7 glass prism (np =1.517) with the help of a laboratory assembled system. The shift in SPR reflectance curve for increasing concentration of target DNA ranging from 10 to180 ng/μl were recorded which shows the promising application of SPR technique towards biosensing. The Sensitivity of the ZnO thin film using SPR is found to be about 0.031°/(ng/μl) with the minimum detection limit of 5 ng/μl. Zinc oxide nanostructures possessing flower-like morphology have been synthesized onto platinized silicon substrate by simple and economical hydrothermal method. The electrochemical sensing response behaviour of the DNA bioelectrode (ssth-DNA/ ZNF/Pt/Si) has been studied by both differential pulse voltammetric (DPV) as well as impedimetric techniques. The fabricated DNA biosensor can quantify wide range of the complementary targets sth-DNA in the range 5–240 ng/μl with good linearity (R=0.98), high sensitivity (168.64μAng/μl/cm2) and low detection limit of about 5ng/μl.

Highly sensitive and fast response gas sensor based on a light reflection at the glass-photonic crystal interface

We develop a versatile gas sensor based on the condition for total internal reflection at the glass-photonic crystal interface and corresponding detection scheme for rapid and precise measurement of vapors. The sensor consists of a vapor sensitive photonic crystal film as a Fabry–Perot etalon coated on a solid substrate (e.g., large face of a glass prism or glass slide). Such scheme and specific physicochemical properties of submicron silica particles provide photonic crystal sensor selectivity due to the capillary condensation of ammonia vapor with a sensitivity of 1ppm with a response time of 100ms.

Dispersion compensation in three-photon fluorescence microscopy at 1,700 nm.

Signal generation in three-photon microscopy is proportional to the inverse-squared of the pulse width. Group velocity dispersion is anomalous for water as well as many glasses near the 1,700 nm excitation window, which makes dispersion compensation using glass prism pairs impractical. We show that the high normal dispersion of a silicon wafer can be conveniently used to compensate the dispersion of a 1,700 nm excitation three-photon microscope. We achieved over a factor of two reduction in pulse width at the sample, which corresponded to over a 4x increase in the generated three-photon signal. This signal increase was demonstrated during in vivo experiments near the surface of the mouse brain as well as 900 μm below the surface.

Electron acceleration by surface plasma waves in the presence of static magnetic field

AbstractElectron acceleration is studied during the resonant interaction of launched electron beam with the surface plasma wave (SPW) in the presence of static magnetic field. A configuration of two parallel metal sheets separated by a vacuum region supports the SPW of amplitude maximum on the two parallel interfaces and minimum in the middle. Kretschmann geometry is used to excite surface plasma mode by shinning laser on a glass prism. Dispersion relation of SPW is established in the presence of magnetic field and smaller cut-off frequencies are observed as compared with that of without magnetic field. An electron beam launched in the middle region, experiences a longitudinal ponderomotive force due to SPWs and gets accelerated to the velocity of the order of phase velocity of the surface wave. The energy gained by electron is higher in the presence of magnetic field as compared with zero magnetic field. The electron energy and trajectory are also presented for varying parameters such as amplitude of SPW and magnetic field strength. In the present scheme, electron beams can achieve maximum 550 KeV energy for the SPW amplitude ESP = 1.2 × 1011 V/m, plasma frequency ωp = 1.3 × 1016 rad/s, and cyclotron frequency ωc/ωp = 0.05.

Plasmon waveguide resonance for sensing glycan–lectin interactions

Carbohydrate-modified interfaces have been shown to be valuable tools for the study of protein–glycan recognition events. Label-free approache such as plasmonic based techniques are particularly attractive. This paper describes a new analytical platform for the sensitive and selective screening of carbohydrate–lectin interactions using plasmon waveguide resonance. Planar optical waveguides (POW), consisting of glass prisms coated with silver (50nm) and silica (460nm) layers were derivatized with mannose or lactose moieties. The specific association of the resulting interface with selected lectins was assessed by following the changes in its plasmonic response. The immobilization strategy investigated in this work is based on the formation of a covalent bond between propargyl-functionalized glycans and surface-linked azide groups via a Cu(I) “click” chemistry. Optimization of the surface architecture through the introduction of an oligo(ethylene glycol) spacer between the plasmonic surface and the glycan ligands provided an interface which allowed screening of glycan–lectin interactions in a highly selective manner. The limit of detection (LOD) of this method for this particular application was found to be in the subnanomolar range (0.5nM), showing it to constitute a promising analytical platform for future development and use in a pharmaceutical or biomedical setting.