Quartz Lens Research Articles

Enhancing the optical properties of organic fluorine compound-encapsulated AlGaN-based ultraviolet light-emitting diodes with Ni/Au reflective electrodes

The development of AlGaN-based high-efficiency UVC-LEDs capable of effectively eliminating viruses and bacteria is desired. In this study, we demonstrate a significant improvement in optical output power (LOP) by applying optical interference technology and organic fluorine compound packaging technology. Experiments and calculations revealed that an improvement in LED die LOP was achieved through adjusting the optical length to approximately 0.7·λ n, resulting in an amplification of light intensity caused by the interference of light emitted perpendicular to the die. Furthermore, by coating the LED die with an organic fluorine compound and packaging it in a quartz lens, the LOP increased by a factor of 1.5. Ray-tracing analysis showed that, due to optical interference, the LOP of the LED die was more dependent on the light output from the top surface than from the side.

Solid–Liquid Hybrid‐State Organic Lens for Highly Efficient Deep Ultraviolet Light‐Emitting Diodes

Deep ultraviolet light‐emitting diodes (DUV‐LEDs) are considered to be the most promising ultraviolet light sources for effective and fast sterilization under the worldwide spread of the coronavirus disease (COVID‐19). However, it reminds challenging to promote the light extraction of DUV‐LEDs owing to the strong DUV light absorption of conventional encapsulation materials. Herein, solid–liquid hybrid‐state gels (SLHGs) to fabricate organic lenses for DUV‐LEDs, which largely enhance the light extraction efficiency without sacrificing the working stability, are proposed. Solid‐state cross‐linked networks of polydimethylsiloxane are used in the SLHG structure to maintain the liquid components of silicone oil and demonstrate excellent formability, DUV transparency (over 90% transmittance in the UVC range), and thermal stability. The radiant power of DUV‐LEDs (275 nm) with the optimized SLHG organic lens is enhanced by 52.5% compared to a commercial quartz lens, achieving a record packaging optical effiency of 1.31 among solid‐state packaging DUV‐LEDs. A sterilization evaluation for SARS‐CoV‐2 demonstrates that the inactivation time can be reduced by ≈25% using the SLHG organic lens. Consequently, herein, a feasible and effective method to enhance the optical performance of DUV‐LEDs and advance their promising potential for disinfection applications is provided.

Analysis of the optical quartz lens centering process based on acoustic emission signal processing and the support vector machine

A method was proposed for analyzing the optical glass lens centering process, and experiments on biplane quartz lenses were performed to determine the material removal rate (MRR) for the hard, brittle material. This study used acoustic emission–sensing technology to monitor the MRR and reconstruct the original shape of the lens. The MRR was evaluated, and an error of 17.87% was obtained. A Taguchi experiment was combined with signal analysis to optimize the process parameters, and a support-vector machine was trained to classify the quality of the grinding wheel; the model had accuracy 98.8%. By using the proposed analysis method, workpiece quality was controlled to an edge surface roughness of < 2 μm, a lens circularity error of < 0.01 mm, a crack length of < E0.1, and an optical axis error of < 150 μrad.

Enhanced Light Extraction of DUV LEDs by Using a Quartz Lens With Three-Dimensional Structure

AlGaN based deep ultraviolet light-emitting diodes (DUV LEDs) have wide applications in many fields, such as air and water purification, disinfection, and biochemical inspection. However, the wall plug efficiency (WPE) of DUV LEDs is relatively low for these applications, which is due to the low light extraction efficiency (LEE) yielding limited light output from LED package. In this work, we proposed a quartz lens with three-dimensional (3D) structure to enhance the light extraction of DUV LEDs. The optical models of DUV LEDs were established and the optical performances of DUV LEDs were investigated by using optical simulation. The DUV LEDs with the 3D quartz lens exhibit higher light efficiency than those with traditional quartz lens structure. Compared with the traditional structure, the light output power of the 3D lens structure is enhanced by 25.93% at the current of 140 mA and the packaged DUV LED can achieve a wide light angle of 153.2°. It is attributed to the significant light extraction enhancement of the sidewall emission from DUV LED chip.

A pseudo-operational trial: An investigation into the use of longwave reflected UV imaging of cyanoacrylate developed fingermarks

This work presents a pseudo-operational study on plastic bags for the detection of latent fingermarks with various types of cyanoacrylates, including the two-step process with basic yellow 40 (BY40) staining and one-step fluorescent cyanoacrylates, Lumicyano and Polycyano. The use of longwave reflected UV (LWRUV) was employed as part of sequential development for all processes; however, detected marks were not unique as subsequent BY40 staining detected these marks as well. The use of BY40 in the sequence is very important, as without its inclusion many fingermarks would be missed. The study also investigated the use of a standard glass camera lens for LWRUV imaging and compared observations to a specific crystal quartz lens designed for UV imaging. The standard glass lens was able to detect all the marks detected with the crystal quartz lens. Lumicyano detected the lowest overall number of marks and both one-step fluorescent cyanoacrylate processes yielded less marks when compared to the two-step process; however, the use of BY40 after Lumicyano and Polycyano resulted in an increase of detected fingermarks. The use of BY40 did not have a major detrimental effect on subsequent LWRUV imaging, although there was no added evidential value.

Luminescence of Femtosecond Laser-Processed ZnSe Crystal

The ZnSe single crystal treatment in air environment with linearly polarized Ti/sapphire femtosecond (fs)laser pulses of the energy density of around 0.04-0.05 J/cm2 with central wavelength of 800 nm and the pulse duration of 140 fs at a repetition rate of 1 kHz generates the laser-induced periodic surface structures (LIPSSs). The setup with a cylindrical quartz lens at normal incidence allowed processing a relatively large area of the ZnSe sample in one pass of the laser beam. Morphology analysis of LIPSS by scanning electron microscopy (SEM) and image processing reveals the existence of two periods of around 200.0 nm and 630.0 nm simultaneously. All LIPSSs demonstrate the orientation perpendicular to the laser beam polarization. The possible nature of LIPSS formation on ZnSe single crystal is caused by the synergetic influence of the interference mechanism involving surface plasmon polaritons and hydrodynamic effects of surface morphology modification. The fs-laser-induced changes of carrier concentrations in ZnSe specify obtained periods of high spatial frequency LIPSS. The influence of femtosecond laser processing on luminescent properties of ZnSe single crystal has been studied by an analysis of the photoluminescence (PL) and X-ray luminescence (XRL) spectra of laser-treated and untreated areas in the visible region of spectrum at room and low temperatures. The PL spectra and XRL spectra, as well as temperature dependencies of XRL spectra or thermally stimulated luminescence curves, demonstrate a good correlation for untreated and fs-laser-treated ZnSe surfaces. Specific PL bands related to the extended structural defects do not appear for LIPSS at the ZnSe sample under an excitation of 337 nm (3.68 eV). The Relative intensities and position of separate components of observed luminescence bands after ultrashort laser treatment do not change significantly. Thus, the structural perfection of the ZnSe single crystal surface is preserved.

Synthesis of Colloidal Silver Nanoparticles in Various Liquid Media Using Pulse Laser Ablation Method and Its Antibacterial Properties

The silver nanoparticles (AgNPs) have been applied as an antibacterial agent in consumer products, cosmetics, and food industries. In this present work, AgNPs were synthesized in various mediums of polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), and chitosan using the pulse laser ablation synthesis method. Experimentally, a pulse Nd:YAG laser beam (1064 nm, 7 ns, 30 mJ) was directed using a silver mirror and focused using a quartz lens with a focal length of 30 mm on a silver metal plate placed in a petri dish containing liquid mediums for 120 min to produce colloidal silver nanoparticles. The results certified that All AgNPs have a spherical shape with polydisperse size in all media, including PVP, PEG, and chitosan. The smallest AgNPs have been produced in PVP medium with an averaged smallest size of 11.62 nm. Based on this result, PVP is the preferred medium to produce AgNPs with the smallest size and good stability. The produced silver nanoparticles have been successfully employed as an antibacterial agent, which is experimentally demonstrated by using Escherichia coli and Staphylococcus aureus. The result certified that the produced silver nanoparticles could effectively kill the bacteria with a killing percentage of 99.6 to 100%.

Effect of quartz lens structure on the optical performances of near-ultraviolet light-emitting diodes.

Near-ultraviolet light-emitting diodes (NUV-LEDs) have been a rising UV light source for identification, resin curing, ink-printing, and illumination. In pursuit of more extensive application in different fields, their optical performances are obliged to be better. In this paper, we investigated the effect of a quartz lens structure on the optical performances of NUV-LEDs. The feature size of the quartz lens was optimized by optical simulations. When the quartz lens has the optimized feature size with a height above 1.8 mm while adding a silicone layer between the chip and the lens, the NUV-LEDs achieve the highest light efficiency, and exhibit a smallest light spot and largest light energy at the center region. Furthermore, different lenses were prepared and applied in the packaging of NUV-LEDs. As a consequence, the light output power of NUV-LEDs with a silicone layer is enhanced by 20.19% at the current of 220 mA. The light output power of NUV-LEDs is enhanced by 38.66%, 43.98%, and 53.30%, respectively, by using the different quartz lenses at the current of 220 mA, and the NUV-LED achieves the highest luminous intensity by 0.098 cd and smallest output light angle by 106.0°. It is attributed to the significant refraction effect of the quartz lens, which improves the optical performances of NUV-LEDs.

Superoscillatory quartz lens with effective numerical aperture greater than one

We report super-resolution high-numerical-aperture and long-working-distance superoscillatory quartz lenses for focusing and imaging applications. At the wavelength of λ = 633 nm, the lenses have an effective numerical aperture of 1.25, a working distance of 200 μm, and a focus into a hotspot of 0.4λ. Confocal imaging with resolution determined by the superoscillatory hotspot size is experimentally demonstrated.

Rejection of the biophoton hypothesis on the origin of photoreceptor dark noise.

Rod photoreceptors of the vertebrate retina produce, in darkness, spontaneous discrete current waves virtually identical to responses to single photons. The waves comprise an irreducible source of noise (discrete dark noise) that may limit the threshold sensitivity of vision. The waves obviously originate from acts of random activation of single rhodopsin molecules. Until recently, it was generally accepted that the activation occurs due to the rhodopsin thermal motion. Yet, a few years ago it was proposed that rhodopsin molecules are activated not by heat but rather by real photons generated within the retina by chemiluminescence. Using a high-sensitive photomultiplier, we measured intensities of biophoton emission from isolated retinas and eyecups of frogs (Rana ridibunda) and fish (sterlet, Acipenser ruthenus). Retinal samples were placed in a perfusion chamber and emitted photons collected by a high-aperture quartz lens. The collected light was sent to the photomultiplier cathode through a rotating chopper so that a long-lasting synchronous accumulation of the light signal was possible. The absolute intensity of bio-emission was estimated by the response of the measuring system to a calibrated light source. The intensity of the source, in turn, was quantified by measuring rhodopsin bleaching with single-rod microspectrophotometry. We also measured the frequency of discrete dark waves in rods of the two species with suction pipette recordings. Expressed as the rate constant of rhodopsin activation, it was 1.2 × 10-11/s in frogs and 7.6 × 10-11/s in sterlets. Approximately two thirds of retinal samples of each species produced reliably measurable biophoton emissions. However, its intensity was ≥100 times lower than necessary to produce the discrete dark noise. We argue that this is just a lower estimate of the discrepancy between the hypothesis and experiment. We conclude that the biophoton hypothesis on the origin of discrete dark noise in photoreceptors must be rejected.

32.1 W/m2 continuous wave solar-pumped laser with a bonding Nd:YAG/YAG rod and a Fresnel lens

We report here significant progress in solar-pumped laser collection efficiency with a grooved bonding Nd:YAG/YAG crystal rod. A Fresnel lens was used as the primary solar radiation concentrator. A gold-plated conical pump cavity with a water filled quartz tube lens was used to concentrate the solar radiation from the focal zone of the primary concentrator into a 6-mm-diameter, 95-mm-length bonding Nd:YAG/YAG crystal rod. To the best of our knowledge, it is the first time of a bonding Nd:YAG/YAG crystal pumped by Fresnel lens solar energy collection and concentration system. For 1.03 m2 effective solar radiation collection area, 32.1 W/m2 collection efficiency was obtained, corresponding to a total slope efficiency of 5.4% and an optical-to-optical efficiency of 3.3%. The performance of the grooved bonding crystal rod was compared with the grooved non-bonding crystal rod. The maximum output power from the grooved bonding crystal rod was 22.6% higher than the value from a grooved non-bonding rod. The M2 beam quality factor was also improved from 126 to 61.

Interface Anchored Effect on Improving Working Stability of Deep Ultraviolet Light-Emitting Diode Using Graphene Oxide-Based Fluoropolymer Encapsulant.

The graphene oxide (GO)-based fluoropolymer is first proposed as an interface encapsulant to improve the light extraction efficiency and achieve the ultralong working stability of deep ultraviolet light-emitting diodes (DUV-LEDs), benefitting from its superior interface performance based on an anchored effect. For the GO-based fluoropolymer composite, the anchored structure is designed to effectively and tightly rivet the quartz lens on the DUV-LED chip by using the interface reaction between GO embedded in fluoropolymer and 3-aminopropyltriethoxy-silane grafted on the surfaces. Experimental results show that on the basis of the interface anchored effect, the air voids in the interface layer of DUV-LED are reduced by 84%, leading to an improvement of the light output power by 15% and a decrease of the junction temperature by 5%, by virtue of the sealing characteristics of the 0.10 wt % GO-based fluoropolymer. In addition, the steady working time is dramatically improved by 660% and it was attributed to the good interface anchored bonding of the 0.10 wt % GO-based fluoropolymer. This novel graphene oxide-based fluoropolymer is believed to provide a feasible and effective interface encapsulant to improve the performance of DUV-LEDs.

Design and Assessment of a 2.5-Gb/s Optical Wireless Transmission System for High Energy Physics

We designed, realized, and tested a 2.5-Gb/s optical wireless communication (OWC) system prototype, that should be employed in high energy physics (HEP) experiments, such as the compact muon solenoid (CMS). The system consists of off-the-shelf components, mainly a vertical cavity surface emitting laser (VCSEL) and a PIN photodiode with a proper ball lens. Since it should be used to transmit data among particle sensors in neighboring rings of the CMS, its target distance is 10 cm. Its most attractive feature is that it does not require a (complex) active tracking system because its measured tolerance to misalignment is around <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula> 1 mm (at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$10^{-12}$</tex-math></inline-formula> bit error rate). We also report the X-rays irradiation tests of all components (Quartz lens, VCSEL, and PIN photodiode): None of them showed any degradation up till 238-Mrad (Si) dose. These results indicate that the designed OWC can be a viable solution for future HEP experiments.

Preliminary fluid inclusion microthermometry results from secondary inclusion planes crosscutting a metamorphic quartz lens from the Mecsekalja Zone metamorphic complex

In this study, new microthermometric data of fluid inclusions distributed along planar assemblages crosscutting a metamorphic quartz lens from the Mecsekalja Zone metamorphic complex are presented. Three fluid generations are defined, none of which have previously been identified by earlier paleofluid evaluations of the study area. Petrographic description of the host quartz is provided to identify textures related to crystalloplastic deformation resulting from ductile deformation. The textural relationship of the studied assemblages to the dynamic recrystallization features is discussed. The possible affinities of the fluids introduced in this study to those identified in the region by previous authors are discussed. The affinities and timing of the fluid flow events are discussed based on the physicochemical properties of the fluids. One local carbonic (high XCO2) fluid is recognized. A high- and a moderate-salinity fluid generation are also revealed. The relationship of these fluid generations to those...

Enhanced Optical and Thermal Performance of Eutectic Flip-Chip Ultraviolet Light-Emitting Diodes via AlN-Doped-Silicone Encapsulant

This paper investigated the optical and thermal performance of the nitride-based ultraviolet light-emitting diodes fabricated by the eutectic flip-chip method. A new packaging structure was proposed by introducing a thin encapsulation layer doped with 0.4 wt% AlN nanoparticles (NPs) and uniform quartz lens simultaneously. Experimental results showed that the packaging structure proposed in this paper could significantly enhance the light output power, reduce the junction temperature, and increase the emission angle compared with the encapsulation layer consisting silicone only. When the NPs concentration increased from 0.1 to 0.4 wt%, the light output power increased from 7.6% to 17.4% at the forward current of 800 mA. Meanwhile, the junction temperature decreased by 5.7 °C, while the emission angle increased by 11.3°. What is more, it was found that the enhancement of light output power depended on the NPs concentration and showed the maximum at the concentration of 0.4 wt%. The enhanced light output power was attributed to the additional light scattering and the increased average refractive index resulted from the NPs introduced in the proposed package structure.

Temperature and electron density in femtosecond filament-induced Cu plasma

Laser-induced breakdown spectroscopy (LIBS), which is also known as laser-induced plasma spectroscopy (LIPS), is a very promising spectral analysis technique for detecting elemental composition. The possibility of remote operation of LIBS is one of the properties, which expands the application scope of this technique. The remote LIBS technique is based on a long-range lens. With the increase of focusing distance, it is difficult to tightly focus laser pulse due to the diffraction limits. The size of focusing spot increases with focusing distance increasing. This will require extremely high laser energy. Femtosecond laser filamentation due to optical Kerr effect can be applied to the remote LIBS. During the filament propagation, the waist of laser beam is close to a constant value. The laser intensity inside the filament is about 1013 W/cm2 (intensity clamping). The intensity is sufficient to ablate sample and produce the plasma. It can overcome the influence of the diffraction limit in nanosecond LIBS. Although many researchers have studied the femtosecond geometrical focusing and femtosecond filamentation LIBSs, the spectral characteristics have not been completely understood. In this paper, we study the femtosecond laser filament-induced Cu plasma spectroscopy. Femtosecond laser system is an ultrafast Ti:sapphire amplifier (Coherent Libra). The full-width at the half maximum is 50 fs at a wavelength of 800 nm with a repetition rate of 1 kHz and its output energy is 3.5 mJ. A quartz lens with a focal length of 1 m is used to focus the laser to generate a filament channel. The spectral intensity of produced Cu plasma along the filament channel is measured by using the optical emission spectroscopy, and the distribution of Cu(I) intensity versus the distance between sample and focused lens is obtained. The results indicate that in a longer distance range along the filament, plasma spectroscopy has stronger emission due to the intensity clamping effect in femtosecond laser filamentation. In addition, we also calculate the plasma temperature and electron density by using the Boltzmann plot and the Stark broadening. The plasma temperature and electron density along the filament channel can be divided into three main regions: region 1) from 950 mm to 970 mm, in which the plasma temperature and electron density increase with the increase of distance; region 2) from 970 mm to 1030 mm, in which the change of plasma excitation temperature is opposite to the change of electron density; region 3) from 1030 mm to 1050 mm, in which the plasma temperature and electron density decrease with the increase of distance.

Composition and metal contents of ore-forming fluids of the Kalguty Mo–W(Be) deposit (Gorny Altai)

Based on results of study of fluid inclusions, we have established the specific fluid regime of formation of the Kalguty Mo–W(Be) deposit (Gorny Altai). Using classical thermobarogeochemistry (cryo- and thermometry) and modern microprobing methods (Raman spectroscopy and LA-ICP-MS), we studied fluid inclusions in quartz of quartz–wolframite veins (ore formation stage I), specific “quartz core” (quartz lens), and pyrite-chalcopyrite-molybdenite paragenesis (ore formation stage II). The results of study show that the quartz–wolframite veins of the Kalguty deposit formed with the participation of reduced W-Sb-bearing fluids with a salt content of up to 5.9 wt.%. Their gas phase consisted of CO2, N2, and CH4. Formation of pyrite-chalcopyrite-molybdenite mineralization involved oxidized hot (530–420 °C) fluids with the average salt content of 9.3 wt.%. Their gas phase was of high density (up to 0.55) and consisted of CO2, N2, and H2S. The pressure of the mineral-forming environment varied from 50 to 25 MPa. The fluids contained Cu, Mo, Bi, and S. The productive greisen-vein Mo–W(Be) mineralization of the Kalguty deposit resulted from the superposition of greisen molybdenite-chalcopyrite mineralization on parageneses of earlier formed quartz-wolframite veins. Oxidized metal-bearing fluids that formed the Mo mineralization of the Kalguty deposit have high contents of S and are geochemical analogs of magmatic metal-bearing ore-forming fluids of the Central Aldan porphyry Cu-Au-Mo deposits, which are genetically related to alkaline massifs. This suggests the significant influence of the mantle source on the formation of the Kalguty rare-metal ore-magmatic system. The same is evidenced from the sulfur isotope composition of chalcopyrite, molybdenite, and pyrite from ore parageneses, falling in the narrow range of δ34S‰ from −1.2 to +2.9 corresponding to the isotope composition of mantle sulfur.

Neutral gas temperature maps of the pin-to-plate argon micro discharge into the ambient air

This study is designed to explore the two dimensional temperature maps of the atmospheric argon discharge consisting of pin-to-plane electrodes supplied by a high voltage DC source. After checking the stability of the micro discharge, the two dimensional image plane focused by a quartz lens was scanned by the fiber probe driven by a 3D Mobile Platform. The rotational and vibrational temperatures are calculated using nitrogen emissions collected by the high resolution spectrometer and high sensitive intensified charge coupled device. The rotational temperature varies from 1558.15 K to 2621.14 K and vibrational temperature varies from 3010.38 K to 3774.69 K, indicating a great temperature gradient due to small discharge size. The temperature maps show a lateral expansion and a sharp truncation in the radial direction. A double layers discharge is identified, where an arc discharge coats the glow discharge.

Fabrication of dual-focus dual-layered microlens

Novel structure of dual-focus microlens array with dual layers is proposed. Dual-focus microlenses formed by combination of dual layers of concentric spherical lenses are fabricated through photo lithography and dry etching processes. The dual lens is formed by combination of a thermally reflowed photo resist lens on a fused quartz lens which is formed by dry etching of the fused quartz substrate.

Near-field light focusing by a slit array in a planar metal film with nonuniform slit dielectric material

We study the interference of evanescent electromagnetic waves generated from multi-slits in a metal film and demonstrate the anomalous bending of light at infrared frequencies due to negative refraction. We also calculate the diffraction of an incident plane electromagnetic waves by a metallic film with an arbitrary linear array of slits, slit separation, and slit dielectric material. In contrast to a double-convex shaped quartz lens, we show that a planar metallic film with a one-dimensional slit array can also focus polarized light in the near-field region when either the slit width or the slit dielectric material becomes spatially nonuniform.