<title>Abstract</title>
Metasurface lenses (metalenses) offer an ultrathin and simple optical system with dynamic functions that include focal length tuning. In this study, a rotational varifocal (i.e., moiré) metalens based on octagonal single-crystal silicon pillars was designed and fabricated to realize a high transmittance, whole 2<italic>π</italic> phase coverage, and polarization insensitivity for visible wavelengths. The moiré metalens consists of a pair of cascaded metasurface-based phase lattices and the focal length can be adjusted from negative to positive by mutual rotation. The fabricated moiré metalens demonstrated a focal length that can be tuned from −36 mm to −2 mm and from 2 to 12 mm by mutual rotation from −90° to 90°, and the experimental measurements agreed well with theoretical values at the design wavelength of 633 nm. Imaging was demonstrated at three distinct wavelengths of 633, 532, and 440 nm.

Objective: In dentistry, dentists perform many treatments with a few visually magnified information. About deep area of root canals, it commonly relies on exploration carried out with the fingers of the dentist, because the root canal entrance is very small to be observed. In clinical practice, the intraoral camera and endoscopic systems are separate devices, and there are no sensors to capture both pictures of the whole tooth and those inside the root canal. Objective of this research is to combine the intraoral camera and endoscopic system facilitating to use clinical practice. Methods: We propose an endoscopic system based on the thin image fiber, SOPROLIFE intraoral camera as an image sensor, and a new adaptor to connect the two parts. We observed resolution charts with 50, 25, 10, and 5 line pairs (LP)/mm patterns. The acquired images are processed to both remove fixed-pattern noise using robust principal component analysis and enhance contrast. Results: The acquired images containing all LP/mm patterns were clear and showed higher contrast after processing. Visibility of the processed images is 1.7, 1.6, 2.2, and 1.9 times higher than that of the raw images for 50, 25, 10, and 5 LP/mm patterns, respectively. Conclusion: Our fabricated endoscopic system based on the SOPROLIFE intraoral camera could observe 50, 25, 10, and 5 LP/mm patterns. After image processing, the noise was reduced, and high-contrast images were obtained. Significance: This system can be considered as a further step toward facilitating noninvasive and contactless systems in clinical practice.

The protection of environment, in a specific manner air component, is one of the most impbrtant objectives established by national and international organizations. Air pollutants are generally detected by electronic instrumentation containing dedicated units from capturing to processing and displaying. With the deterioration of anthropic activities due to, for example, increasing of car traffic, increasing of heavy industrial activities, and subsequent greenhouse effects, the nature of required value becomes very complex and attention must be paid to "stealth" pollutants and mechanisms that produce them. That is why, beyond traditional pollutants, attention must be paid to specific classes of pollutants such as dusts vectoring fixed in inodorous gases, and other components included in gaseous substances as dioxins and furans. This paper illustrates results of experimental activities within a review approach for detecting pollutants based on advanced technology using nanoparticle through helium microwave-induced plasma, sensors exploiting perovskite structures and thermography for detecting harmful gases. Longterm detection of dioxins is also illustrated. (C) 2016 Elsevier Ltd. All rights reserved.

A laser-based emission-type diagnostic technique using laser-induced breakdown spectroscopy (LIBS) for the in vivo analysis of tooth enamel is described. The system aims to improve the promptness of laser dental treatment and accuracy of identifying early caries from healthy teeth. Our research group has been developing the LIBS system for various applications. In addition to the research on the LIBS system, a novel microdental endoscope to observe fractures near the root apex has been developed in a recent study. The LIBS system for dentistry presented in this paper is the first attempt to combine the techniques of the microdental endoscope and the spectroscopic measurement from our group. In the LIBS operation, not only the elemental information is obtained, but also the pulse-operated-condensed laser generates microsized plasma on the surface of the materials when it removes trace substances. The combination technique using LIBS with the microdental endoscope allows noncontact dental diagnosis with chemical analysis and dental treatment at the same time.

With the development of dental instruments, such as dental microscopes and cone beam computed tomography, the precision of current dental diagnosis and treatment has greatly improved. However, the observation of deep periodontal pockets, fractures near the root apex, and collaterals of root canals is difficult using these instruments. To solve these problems, we developed two types of micro-image sensors that can be used for the observation of root canals. The first image sensor is an external-irradiation probe that uses an external light source. This probe has high resolution and a wide field of view. The other sensor is an internal-irradiation probe, which can be used to observe an image and transmit the illumination light with a single probe. The external-irradiation probe has an image fiber with a diameter of 600 mu m and a gradient index (GRIN) lens. The internal-irradiation probe has an image fiber with a diameter of 300 mu m, a GRIN lens, and 40 optical fibers with a diameter of 40 mu m each as a light source. Using these probes, we captured the image of a resolution chart; line spaces with the widths of 10-100 mu m were observed using both types of probes. The evaluations of the visibility of the captured image showed higher measurement values than those of commercially available endoscopes. We will apply this ultra-compact image sensor to various fields besides dentistry, such as medical and industrial applications.

We report a new laser scanning device to be used in a laser-induced breakdown spectroscopy (LIBS) system. The system consists of a tunable lens, a cold mirror that transmits infrared wavelengths, two galvano mirrors, a condenser lens, and an optical axis adjusting laser. Conventional laser scanning technologies have two main applications: (i) in the industry, for drawing simple dots/lines with high power lasers; and (ii) in laser art projections, where far more complex illustrations and animations using visible lasers have been achieved. These two applications have been developed separately. Our scanning system combines the advantages of both these technologies by employing high-strength galvano mirrors as well as a driving system that meets the international laser display association (ILDA) standard. Moreover, by assembling the electrically controlled tunable lens, any measuring point where the generation of laser-induced plasma is needed, can be reached in a given space.

Recently, AT-cut quartz resonators have found widespread use as RF and high-sensitivity devices. In these applications, further miniaturization and high-frequency stability are required. To achieve a high quality (Q)-factor and high productivity, the authors have proposed a novel resonator shape in which the surface is machined as a three-dimensional stripe-like structure. This shape is called quasi-convex. In this paper, we discuss the design and fabrication of quasi-convex resonators to verify their effectiveness. First, with regard to the height of the convex part and the pitch of the quasi-convex pattern, the optimal resonator design is discussed on the basis of the results of a finite-element method simulation. Then, prototypes of the quasi-convex resonators fabricated by deep reactive-ion etching and micro electro-mechanical systems fabrication technology are presented. In our experiments, the highest Q-factor is obtained when the height ratio of the convex part was 5% and the pitch is 100 μm. In addition, the Q-factor of the quasi-convex resonators is seven times greater than that of ordinary plane-shaped resonators, as confirmed using vacuum equipment. © 2014 The Institute of Electrical Engineers of Japan.

The purpose of this research is to detect the atomic spectrum of cesium using laserinduced breakdown spectroscopy (LIBS). In this study, pollucite ((Cs,Na)(AlSi2)O6.nH2O) was used as a test sample for the LIBS measurement. LIBS is a useful tool for the determination of the elemental composition of various materials and it does not require any preprocessing step. The Nd:YAG laser was operated at 1064 nm to generate a 50-mJ Q-switched pulse with a width of 8 ns (full width at half maximum, FWHM). The breakdown emissions were dispersed by a grating with a groove density of 1200 lines/mm and the resulting electrical signal was recorded using a streak camera. The plasma intensity was optimized with respect to the background. Spectral measurements were carried out after an appropriate delay time to allow for the decay of the continuum radiation. In the experiments, 100 laser shots were used to record data for each spectrum in ambient air. The results of the experiments showed that the atomic signals corresponding to pollucite were obtained easily by LIBS measurements. Thus, spectrum peaks due to cesium, sodium, aluminum, and silicon are observed. In particular, the characteristics of the cesium spectrum play an important role in establishing the LIBS system for environmental monitoring, which may be used to detect radioactive elements emitted from nuclear plants. © (2013) Trans Tech Publications, Switzerland.

This report describes an optical sensing system for fine particle detection using a combination of two techniques: laser-induced breakdown spectroscopy (LIBS) and laser-induced incandescence (LII). We have improved laser measurement systems applied for small-particle analysis. We have determined elemental composition and density of particles using LIBS and have been able to measure particle size using LII. Controlling the power density of the light source of the present system allowed switching from LIBS to LII. LII temporal analysis was conducted using a streak camera, which was also used for LIBS analysis. The LII technique allows in situ measurement of the average primary particle size of nanoscale soot particles.

A camera module employing spherical single-element lens imaging system (SSLIS) is introduced in this study. This type of imaging system can be used in compact digital cameras or mobile phone cameras, and it provides the advantages of simple design, reduced device bulkiness, and reduced manufacturing costs. When compared with conventional camera modules, our system produces radially variant blurred images, which can be satisfactorily restored by means of a polar domain deconvolution algorithm proposed in our previous study. In this study, we demonstrate an improved version of this algorithm that enables full-field-of-view (FOV) image restoration instead of the partial FOV restoration obtained via our previous algorithm. This improvement is realized by interpolating the upper and arc-shaped boundaries of the panoramic polar image such that the ringing artifacts around the center and four boundaries of the restored Cartesian image are greatly suppressed. The effectiveness of the improved algorithm is verified by image restoration of both computer simulated images and real-world scenes captured by the spherical single lens camera module. The quality of the restored image depends on the overall sparsity of all the point spread function (PSF) block Toeplitz with circulant blocks (BTCB) matrices used to restore a radially blurred image. (C) 2012 Optical Society of America

Among few existing applications of Microstructured Optical Fibers, a new device for measurement of low gas concentration was designed. Developed set-up based on a Photonic Bandgap Fiber (PBGF), which was used as a gas cell. Proposed technique allowed reducing gas sample volume to 0.01 cc. The gas flow inside core of fiber was simulated and result was confirmed experimentally. During the experimental work several types of fibers of various parameters were specially designed, produced and used. Core diameters ranged from 10.9 μm to 700 μm. Various cutting techniques for fibers were investigated. © 2008 The Institute of Electrical Engineers of Japan.

This study reports on the development of an optical gas sensor device with an absorption peak at a selected wavelength using UV plasmon resonance absorption. The structure of the gas sensor device consists of a single nanoscale Al plates vertically aligned on a glass substrate. The absorption spectrum depends on the dimensions of the Al plate and substrate, and the angle of incidence, and was optimized by calculating the electric field through finite element simulation using COMSOL Multiphysics 6.0. The results show that by controlling the x-directional pitch, it is possible to induce plasmon resonance at wavelengths matching the absorption wavelengths of ozone and ammonia with only one dimension. Using the design dimensions, the gas sensor device was fabricated and the structure was observed.

In this study, dielectric metasurface holograms employing single-crystal Si as the meta-atom were fabricated. The angular spectral method calculated the phase distribution and represented it by an array of octagonal c-Si pillars with different widths at a resolution of 16384 x 16384. The design values of the metasurface are the pitch
between the pillars is 280 nm, the height of the pillars is 400 nm, the diameter of the pillars is 140 nm to 210 nm, and the size of the hologram is 4.5 mm square. The substrate was patterned by electron beam lithography, and the Si pillars were formed by reactive ion etching. White light was incident on the fabricated holograms for projection. The projected 3D images were successfully observed with the naked eyes.

High transmittance multicolor metasurface holograms were fabricated using SiN pillars as meta-atom. The phase distribution on the hologram surface was calculated by the iterative Fourier transform method at the design wavelengths of 445 nm, 532 nm, and 633 nm. The fabricated hologram showed successful projection of color image with high brightness and color matching to the target image. The average transmittance calculated by microspectroscopy was 98％, which was much higher than that of previous studies.

© 2017 IEEE. This paper describes a preliminary test for sum-frequency generation (SFG) spectroscopy analysis of lipid polymer membranes. The SFG technique is used to analyze surface and structural information of molecules at gas-solid, gas-liquid, liquid-solid interfaces. A specially designed SFG system, which allows to analyze orientational polarization of polymer molecules at interfaces between a lipid polymer membrane and liquid/gas/solid, is being developed in our laboratory. A laser-induced damage threshold test of lipid polymer membranes was conducted in an early stage of this work.

In dentistry, endodontic treatment becomes necessary when dental caries progresses deep into the tooth and reaches the dental pulp or the periapical tissue. A large part of this treatment is performed without direct observation of the root canals. Previously, we reported a prototype of a dental endoscope. In this study, we attempted to develop a novel image sensor for dental endodontic diagnosis and treatment that allows capturing an image of the fine constructions inside the root canals. Our fabricated probe contains an image fiber, a GRIN lens, and optical fibers as light sources. These materials are encased inside a stainless steel tube to ensure the durability. In previous experiments, we attempted to connect all materials in one step. However, the captured images had deviations along the center axis between the image fiber and GRIN lens. To solve this problem, we considered a new, two-step method for connecting the two materials. In this method, an image fiber and a GRIN lens with the same diameter were placed on stages capable of three-dimensional fine positional adjustments at a resolution of 0.01 mm. The surfaces of the materials were connected under observation through a microscope. An evaluation of the captured images showed that the deviations in the previous images were 22.4 µm along the X-axis and 45.7 µm along the Y-axis. In contrast, the deviations with the new method were 16.7 µm and 8.9 µm along the X-axis and Y-axis, respectively. Therefore, the new method greatly improved precision along each axis. With this method, our fabricated probe could capture and evaluate images more efficiently. We are now trying to fabricate and evaluate a new image sensor.

The development of dental instruments such as dental microscope and cone-beam computed tomography has greatly improved the precision of current dental treatments. However, observation of fractures near the apex collateral of the root canal remains difficult when using these instruments. In this study, we developed two types of probes: an ‘external-irradiation system’ and an ‘internal-irradiation system’. The external-irradiation probe is composed of an image fibre with a diameter of 500 μm and a gradient-index lens (GRIN lens) with the same diameter as the image fibre. The internal-irradiation probe is composed of an image fibre, GRIN lens, and five optical fibres for illumination, with diameters of 300, 250, and 65 μm, respectively. In an observation experiment of the resolution chart using these probes, both probes could observe lines and spaces of 10–100 μm using an external light source. To evaluate resolution, visibility was measured for each image, and higher visibility was observed as the lines and spaces were increased. We attempted to illuminate the observation area with optical fibres inside the probe
however, it was difficult because of the low intensity of the light. Furthermore, we observed the actual root canal of an extracted tooth. In future, we would like to redesign the GRIN lens and a suitable offset of the optical fibres.

This chapter describes the elemental analytical technique of the fine particles using atomic emission spectroscopy system for an environmental pollution monitoring. Based on our previous measurement reports, differences of the usage between the laser-induced breakdown spectroscopy (LIBS) system and the helium-microwave-induced plasma-atomic emission spectroscopy (He-MIP-AES) system are explained. Both systems were developed to allow to fulfil the criteria prescribed by the Ministry of Environment, Japan, for measuring the chemical components of particulate matter (PM) by introducing additional original sampling systems. In current environmental monitoring systems, PMs are typically collected on trapping filters placed across Japan and classified as either suspended particulate matter (SPM) or PM2.5 depending on the size. The collected PMs are subsequently analysed with automated measurement instruments such as a piezo balance and with methods such as beta ray attenuation and light scattering. While these measurement methods allow the mass concentration of PMs in the air to be obtained at hourly intervals, the chemical composition of individual particles is analysed with time-intensive laboratory procedures. In contrast, the LIBS and He-MIP-AES measurement system allow the chemical compositions and particle sizes to be measured simultaneously in real time.

My research focused on improving the performance of AT-cut high-frequency quartz resonators, which have been used in a wide range of applications including frequency generators, frequency control of telecommunication systems. New research findings about optimal design of AT-cut high-frequency quartz resonators fabricated by newly developed etching process were presented through improving energy trapping and reducing spurious vibration couplings. The simulation and experimental verification were carried out, and the effectiveness of the optimal design was validated. The main optimal design works include five cases.

In this paper, we discuss electroplating method to deposit platinum catalyst called platinum black on the both-side of sensor on a quartz wafer to improve sensitivity of hydrogen sensors using quartz resonators. By increasing current density until th limiting current density, the platinum black films were deposited on the electrodes of sensors in a stable. Under the constan current condition, controllability of film thickness of platinum black by time was confirmed. As a result of comparison to th sputtered platinum thin film catalyst, the platinum black catalyst showed higher catalytic activity.

The entrance of a tooth root canal is very small to the naked eye, and in most cases, dentists operate blindly to perform the treatment using an instrument. Particularly, the observation of fractures near the root apex and collaterals of root canals is difficult even using the latest dental instrument. To solve these problems, we attempted to develop a novel dental endoscope. In this study, we developed micro image sensors that can be used for observation of root canals and evaluation of the image sensor visibility. Previous methods have only single line visibility; however, the new method enables evaluation of the sectional visibility in the screen area. Compared with commercially available image sensors, the new image sensor has more than two times higher sectional visibility. Hence, the most focusing area can be analyzed and the aforementioned problems can be solved to improve image sensors. Moreover, not only the micro image sensors but also other sensors can be evaluated quantitatively using this new method.

With the development of dental instruments such as dental microscopes and techniques like cone-beam computed tomography (CBCT), the precision of dental treatment has greatly improved. However, the observation of fractures near the apex collateral of root canals using these instruments remains difficult. In this study, we developed two types of probes that employ external and internal irradiation, respectively. The external-irradiation probe comprises an image fiber and a gradient-index (GRIN) lens, each with a diameter of 500 mu m. The internal-irradiation probe comprises an image fiber 300 mu m in diameter; a GRIN lens 250 mu m in diameter; and five optical fibers for illumination, each 65 mu m in diameter. Both probes observed lines and spaces 10 to 100 mu m in width on a sample when using a light source from the outside. The visibility of the obtained images increased with the width of the lines and spaces. The illumination of the observation area with the optical fibers inside of the probe was difficult because of a lack of light. In this study, we obtained high-resolution pictures of a root canal. In the future, we will re-design the lens to determine a suitable offset for the optical fiber.

This paper reports on a helium-microwave-induced plasma-atomic emission spectroscopy (He-MIP-AES) system with two-way spectroscopic analysis that fulfills the criteria prescribed by the Ministry of Environment, Japan, for measuring the chemical components of particulate matter (PM). The He-MIP-AES system is a reconstruction of a commercial particle analyzer system. In current environmental monitoring systems, PMs are typically collected on trapping filters placed across Japan and classified as either suspended particulate matter (SPM) or PM2.5 depending on the size. The collected PMs are subsequently analyzed with automated measurement instruments such as a piezo balance and with methods such as beta ray attenuation and light scattering. While these measurement methods allow the mass concentration of PMs in the air to be obtained at hourly intervals, the chemical composition of individual particles is analyzed with time-intensive laboratory procedures. In contrast, the presented measurement system allows the chemical compositions and particle sizes to be measured simultaneously in real time.

This chapter describes the validity and usefulness of laser-induced breakdown spectroscopy (LIBS) measurements enhanced by argon nanobubbles. The use of argon nanobubbles in the LIBS system revealed higher sensitivity as compared to other conventional methods that are used for LIBS solution measurements. To create the nanobubbles, argon gas was pumped into water, forming bubbles less than 100 nm in diameter. The solution of dissolved argon bubbles was used to measure (1) the atomic spectrum of hydrogen (λ = 656 nm) from the water molecules (H2O) in the solution, and (2) the atomic spectrum of nitrogen (λ = 399.5) from the air bubbles in the solution. These experimental results demonstrated that argon nanobubbles are able to instantaneously retain plasma during the excitation/relaxation period, which is essential for highly sensitive spectral measurements. The intensity of nitrogen spectra (measurement (2)) obtained from the argon-air nanobubbles in water was much higher than that of the spectra obtained from normal LIBS air measurements.

In this work, a new method for real-time in-situ environmental monitoring of measured radioactive elements is presented. Currently, germanium semiconductor detectors are used for the analysis of radioactive materials. Germanium semiconductor detectors exhibit sensitivities much higher than those exhibited by other analytical instrumentation techniques. However, the equipment is lab-based and cannot address the need for on-site monitoring. Moving radioactive samples is strictly legally prohibited for safety reasons. The frequency of use is limited by the facility installation space, workforce supply considerations regarding safety, legal considerations for carrying and storing radioactive samples, and waste disposal methods. The presented method using laser-induced breakdown spectroscopy (LIBS) offers an affordable sensing system that can be applied at point-of-use for environmental analyses to provide an indication of impending problems. The applicable range of conventional LIBS, which has been used only to determine the elemental composition, is expanded to obtain an estimate of the isotope ratio by measuring the variation due to temporal changes in the atomic disintegration products. This method takes full advantage of LIBS, such that no pretreatment of the measured sample is required. In this work, a confirmation test for the LIBS measurement of cesium and barium based on the results of the disintegration of cesium is demonstrated as part of a preliminary survey for developing a monitoring system for actual radioactive materials.

A contactless sensing system for nano-sized carbonaceous particulate matter using laser-induced incandescence (LII) and laser-induced breakdown spectroscopy (LIBS) is presented. The LIBS technique allows detecting elemental composition and density of the SPMs, and LII technique allows to measure particulate size. LII technique is temporal resolved method that enables measurement of soot particulate sizes in a combustion process. In the case of the measured material consisting of a carbonaceous element, it is easy to determine the particulate diameter distribution derived from the time-profile of emission attenuation signals during cooling process, because the cooling behaviour is characteristic of the particulate diameter in LII technique. However, in actuality, the SPMs consist of several different types of elements. By using LIBS technique, the elemental analysis is able to conduct easily.

We developed a focal positioning system for laser sensing instruments. The positioning system consists of x- and y-axis galvano mirrors and a high-speed response tunable lens. It allows for quick adjustment of the measuring position with high resolution and repeatability afforded by the galvano mirrors, which enable the plotting of 10,000 focal points per second, and the tunable lens, which allows adjustment of the focal length within 2.5 ms (10%-90% step). For laser measurements, the location information of the laser spot on the sample is the key parameter to determine the quantitative difference in chemical compositions at different locations. Furthermore, if the sample changes location systematically with some temporal variation, quick correction before changing the default position is required to prevent missing the target. The laser spot positioning system we present here can play an important role in obtaining multi-plot measurements for complicated surface topologies and dynamic micro-samples.

In this paper, dimension optimization of supporting portion was carried out for an originally designed high-frequency fundamental AT-cut quartz resonator, which has a firstly applied peripheral electrode and 10-μm-thin vibration portion to generate above 150 MHz fundamental thickness-shear vibration. Using three-dimensional finite element modeling, it is the first time
dimensions of supporting portion were optimized through improving energy trapping and reducing vibration couplings. Based on optimization results, resonators with different dimensions were fabricated and their Q-factors were measured. The experimental results were very consistent with the optimization results. Improvement of the resonator's performance ensured the validation of our method.

In this paper, we present a point spread function (PSF) filtering technique for solving the radially variant blur restoration problem. Radially variant blur is generated by a spherical single-element lens imaging systeth (SSLIS) that is embedded in an experimental camera module. The restoration of this category of blur is carried out in a polar coordinate system using polar PSFs at different fields of view (FOVs). However, restoration using large PSFs tends to introduce severe ringing artifacts in the restored image owing to the nonsparse nature of these PSFs. We show in this paper that the PSF filtering technique can effectively minimize ringing artifacts by filtering out some PSF pixels with an intensity lower than the threshold intensity. As a result, a nonsparse PSF becomes a sparse PSF, which is for good restoration results. The effectiveness of the PSF filtering technique was validated by visual comparison using three test images captured by the SSLIS camera module. In addition, a systematic way to determine the optimal filtering coefficient for a PSF at any FOV within the FOV range is also introduced.

In this paper, we propose a low cost diagnostic system for dental therapy. This system is capable of carrying out real time observation inside the narrow root canals of oral cavity with high precision and without blind areas using a single graded-index image fiber (GRIN image fiber). The system uses the GRIN image fiber to irradiate the sample to be observed and return the sample image back to the CMOS image sensor of the microscope through the same image fiber, which is different from conventional system that uses separate fibers for illumination and observation. The results suggest that this device can illuminate and observe sample patterns of up to 10 mu m line and space widths with approximately the same quality as those illuminated by external light source. This precision is sufficient to detect cracks and collaterals of the root canals.

This paper demonstrates the validity and usefulness of laser-induced breakdown spectroscopy (LIBS) measurements enhanced by argon nanobubbles. The use of argon nanobubbles in the LIBS system revealed a higher sensitivity than that of conventional methods for LIBS solution measurements. To make the nanobubbles, argon gas was pumped into water, forming bubbles less than 100 nm in diameter. The solution of dissolved argon bubbles was used for the following measurements: (1) the hydrogen atomic spectrum (lambda = 656 nm) from the water molecules (H2O) in the solution and (2) the nitrogen atomic spectrum (lambda = 399.5 nm) from the air bubbles in the solution. These experimental results demonstrated that the argon nanobubbles have the ability of instantaneous plasma retention during the excitation/relaxation period, which is essential for highly sensitive spectral measurements. The intensity of nitrogen spectra (measurement (2)) obtained from the argon-air nanobubbles in water was much higher than that of the spectra obtained from normal LIBS air measurements.

This report presents a new cesium sensing method that uses laser-induced breakdown spectroscopy (LIBS). Conventionally, beta rays and germanium semiconductor detectors have been used for Cs-137 analysis. These methods typically require laboratory-scale analytical facilities. On the other hand, LIBS allows for direct elemental composition measurement of samples regardless of their physical state without preprocessing or laboratory facilities. Even if it is nearly impossible to separate isotopic data from the spectrum of an LIBS measurement, measurement of cesium levels is important for investigating the causes of abnormal radiation levels because the abundance of cesium is low under normal conditions. We report on cesium spectra results as measured by LIBS; the measurements were of sufficient resolution to obtain quantitative information for calculating the expected quantity of radioactive cesium from the isotope ratios.

Increasing functional density of portable electronic devices has led to the explosive growth in the array-based package (ABP) usage, however, the decreasing I/O pitch of ABPs and the consequent smaller pads and solder joints, along with the introduction of brittle lead-free solder alloy, make the interconnect reliability of portable electronic devices more challenging. In this paper, triaxial strain gage array technology was used for monitoring the strain response of laptops under various field use conditions, including rotating a screen, knocking keys, holding a laptop, and so on. The failure analysis results for the ABP assemblies subjected to the above loadings indicated that there was obvious positive correlation between the extents of solder joint damage and strain level around the corresponding areas. In addition to assessing the interconnect reliability risk during different events, the triaxial strain gage array technology can also be applied to compare the impact of mechanical structure design modifications to the solder joint reliability and determine the optimal design.

This paper describes the semi-quantitative analysis of metal nanoparticle ink using laser-induced breakdown spectroscopy (LIBS). LIBS can be used to obtain information about the density and chemical composition of silver particles or copper particles, even ultrafine particles. Metal particles have been attracting much attention because of their increased use in new micro-nano technologies. In this work, LIBS was used as a fine metal particle measurement system for nanometallic materials used in printing. Good spectral peak resolutions were obtained when the Ag spectra were recorded at wavelengths of 328.068 nm and 338.289 nm and Cu spectra at 324.754 nm and 327.396 nm.

This paper describes the quantitative analysis of silver nanoparticle ink using laser-induced breakdown spectroscopy (LIBS). LIBS can be used to obtain information about the density and chemical composition of silver particles, even ultrafine particles. Metal particles have been attracting much attention because of their increased use in new micro-nano technologies. In this work, LIBS was used as a fine metal particle measurement system for nanometallic materials used in printing. This paper reports new developments for quantitative analysis of silver nano particles. Good spectral peak resolutions were obtained when the spectra were recorded at wavelengths of 328 nm and 338 nm. © 2011 IEEE.

This report describes a real-time sensing system for the detection and analysis of fine metal particles using laser-induced breakdown spectroscopy (LIBS). In conventional particle measurement methods, the scanning mobility particle sizer (SMPS) is widely used to obtain particle size distributions. However, when more details on particles are required, another chemical analysis must be performed separately from the one involving the SMPS. Hence, it is difficult to obtain the size and composition of fine particles in real time by conventional methods. By the proposed LIBS method, it is possible to obtain information on the density of fine particles as well as the chemical components of even ultrafine particles. Metal particles are focused on because the use of metal nanoparticles is expanding with emerging micro- and nanotechnologies. This work describes the use of the LIBS system as a fine metal particle monitoring system in a fabrication process using nanometal materials.

This paper reports a novel method for evaluating strain gages. In this method, the evaluated gage is attached at a specific location of coupon board, and then deflects 5 known distances by steps by the insertion of shims with different thicknesses. The strain for each bended status is recorded and can be compared against expected variation. If the principle strain values and corresponding angles within the tolerance, the gage passes the test and can be applied in practical strain measurement with increased confidence, otherwise it will be deprived of the qualification to accept. Moreover, this method combines with accredited gages can also be used to find and eliminate many errors due to gage placement, gage attachment, measurement equipment setup, and lead wires. In order to prove the validity of the given method, three types of gages from various suppliers at are evaluated, and the results of test broadly consistent with technical backgrounds of their respective manufacturers.

This paper presents a new sensing system for carbonaceous nanoparticle measurement using a laser-induced incandescence (LII) technique. Our research group has improved the laser-induced breakdown spectroscopy (LIBS) system used for quantitative analysis. Although the basic principles of LIBS quantitative measurements are well understood, several uncertainties remain concerning complete descriptions-especially for particle size measurement. The elemental composition and density of the particles are determined using LIBS, and particle size measurements are accomplished with the help of LII. In the case of the present system, with temporally resolved LII, measurement of soot primary particle sizes is feasible in a combustion process derived from the ratio of emission signals after a laser pulse because the cooling behaviour is characteristic of the particle size. The LII temporal analysis was performed by a streak camera, which was also used for LIBS analysis. The LII technique allows in situ measurement of the average primary particle size of nanoscale soot particles. © 2011 The Institute of Electrical Engineers of Japan.

In this paper, we propose an advanced approach to particle analysis, involving laser-induced breakdown spectroscopy (LIBS) and laser-induced incandescence (LII) temporal analytical techniques. Various technical properties of fine particles are analyzed via LIBS and LII. LIBS is a useful tool for determining the elemental composition and relative concentration of various materials, whereas LII facilitates the measurement of particle size. Both techniques do not require any pre-processing. The combined use of the LIBS and LII techniques enables highly synergistic fine particle measurement. In the LIBS section, we propose spectrometric analysis via a novel ink-jet technique, and we discuss the effectiveness of Ar as a surrounding gas. In the LII section, we compare the calculated particle size prediction with the experimental results. © 2011 Springer-Verlag Berlin Heidelberg.

This report describes a new sensing system for carbonaceous particles detection using combination with two techniques of laser-induced breakdown spectroscopy (LIBS) and laser-induced incandescence (LII). Our research group has improved LIBS system applied for quantitative analysis. Although the basic principal of the LIBS quantitative measurements were well understood, several uncertainties still remained for complete description especially for the particle size measurement. Elemental composition and density of the particle were determined by using LIBS. Particle size measurement was accomplished with the help of LII. On the presented system, only controlling the power density of the light source allowed to switch from LIBS to LII.

The setup, micro-droplet sampling system combined with a gas-flow system for measurement using laser-induced breakdown spectroscopy (LIBS) is introduced. This setup was designed for high sensitive quantitative analysis using ink-jet technology and gas-flow assistance. The setup presented here allowed precise detection of a uniform volume of 30-μm micro-droplet location for guiding it into a 53.2-μm beam spot area, under the effects of any ambient gas. In this paper, experimental results with the use of two kind of ambient gasses
air and argon gas, were compared in order to find proper time-delay values for time-resolving spectroscopy. From time-gated spectroscopy analysis of these experiments, different relaxation time spectral data were obtained. This result indicates that in the case of using argon ambient for assistance, broader range of time-gate setting is required as compared with the case of using air ambient. Sensitive LIBS measurement for trace elements was shown by using the proper gate-setting value. © 2009 The Institute of Electrical Engineers of Japan.

In this paper, laser-induced breakdown spectroscopy (LIBS) using micro-droplet NaCl solution and set-up for control of micro-droplets are described. Micro-droplets controlling technique is important for solution quantitative analysis. In this study, micro-droplet ejection system for sampling is designed and presented. This micro-droplet ejection system enable a constant volume of the sample liquid to be obtained and it takes advantage of the liquid physical state
the density of the solution can be controlled accurately. The method presented here generates small droplets (diameter 30 μm) by confining the entire volume of the sample material in the laser beam spot area (minimum beam spot diameter: 53.2 μm) and separating it from its surroundings. Using this liquid micronizing method, improved sensitivities are obtained. The Advantage of LIBS is a useful method for determining the elemental composition of various materials regardless of their physical state (solid, liquid, or gas) and without any preprocessing
it is a type of atomic emission spectroscopy (AES). Despite the advantage of qualitative analysis, quantitative analysis is difficult because of sample and plasma fluctuations. Generating constant volume of micro-size sample and proper sample control technique contribute to LIBS quantitative analysis. © (2009) Trans Tech Publications.

A new setup for laser-induced breakdown spectroscopy (LIBS) is introduced. This setup was designed for high sensitive quantitative analysis using the ink-jet technology and gas-flow assistance. The setup presented here allowed precise detection of a micro-droplet for guiding it into a laser beam spot area. The micro-droplet ejection system created constant volume of sample liquid and taking advantage of liquid physical state
density of the solution can be controlled accurately. That means the constant amount of media was maintained in a micro-droplet. This sampling system allowed generating small droplet (diameter 30 μm) confining the whole fixed volume of the sample material in the laser beam spot area (minimum beam spot diameter 53.2 μm), under the effects of any ambient gas. In this paper, the stability with practical use and improvement of detection limit for LIBS measurement is reported. © 2008 IEEE.

A new and reliable set-up for laser-induced breakdown spectroscopy (LIBS) which enabled the precise micro-droplet observation and guiding the solution samples into a laser beam spot area was designed. The method presented here allowed micronizing of the liquid sample confining the whole volume of the sample in the laser beam spot area (minimum beam spot diameter 53.2um, micro-droplet diameter 30-40μm), separating it from its surroundings. As a result, LIBS with the micro-drop ejection system produced greater intensities than the old technique of bulk-liquid measurement based on data from 100 laser pulse shots. Advantages of this method were: strong emissions, no sample splashing, solution density controllability and ho chemical denaturation. This experimental set-up helped to overcome the disadvantage of LIBS with a micro-drop ejection system. © 2008 The Institute of Electrical Engineers of Japan.

A new and reliable evaluating method for a laser induced breakdown spectroscopy (LIBS) quantitative measurement using a micro-droplet sample ejection system is introduced. LIBS has been investigated extensively to establish proper chemical analysis of specimens. There is an indefinable boundary which is ablated or not when laser focusing on the sample. Generating micro-droplets from concentration tuned solution, and leading to the correct beam spot area are important for determining the total amount of media in a droplet. The LIBS measures the sodium chloride concentration of a micro-droplet as a quantitative measurement by recording intensity from the sample plasma. As a result, LIBS with the micro-drop ejection system produced greater intensities than the old technique of bulk-liquid measurement based on data from 100 laser pulse shots.

We have developed high-sensitivity in-situ measurement technology based on photons with visible to ultraviolet wavelength bands. This measurement technology builds on plasmatizing particles technology and a high-sensitivity measurement technology for measuring photons from the plasma. Thus, we have established a technology for measuring particle sizes and the constituent element content of particles with 10% accuracy.

The laser-induced breakdown spectroscopy (LIBS) using micro-droplet sodium chloride solution is presented. Since the 1980s, many liquid miniaturizations of analytical technique for LIBS measurements were reported. The method we present allowed micronizing the sample in such a way that whole volume of a sample was confined in the laser beam spot area (minimum beam spot diameter 53.2μm, microdroplet diameter 50-60μm) and was separated from its surrounding condition. If the sample's physical state was liquid, the density of solution could be controlled as needed. In this paper, originally designed ink-jet system for sampling procedure was presented. According to the new method, improved sensitivity for drawing calibration curves with the aim of the LIBS quantitative measurement were obtained.

The laser-induced breakdown spectroscopy (LEBS) using micro-droplet sodium chloride solution is presented. Micronizing the sample made possible that whole volume of a sample was confined in the laser beam spot area and was separated from its surrounding condition. If the sample's physical state was liquid, the density of solution could be controlled as needed. Originally designed ink-jet system for sampling procedure was presented. According to the new method, improved calibration curves for the LIBS quantitative measurement were obtained.