To evaluate the atomization and evaporation processes of liquid fuel, there are several laser diagnostics available in present. In this paper, the recent progress in laser diagnostics for atomization and evaporation will be introduced, as two categories: atomization and evaporation. The diagnostics for the former includes the primary breakup from liquid jet to ligaments or droplets and the secondary atomization from a bigger droplet to a smaller one, and the latter includes the droplet evaporation and the vapor distributions in a spray.

To characterize the structural and dynamic properties of soft materials and small particles, information on the relevant mesoscopic length scales is required. Such information is often obtained from traditional static and dynamic light scattering (SLS/DLS) experiments in the single scattering regime. In many dense systems, however, these powerful techniques frequently fail due to strong multiple scattering of light. Here I will discuss some experimental innovations that have emerged over the last decade. New methods such as 3D static and dynamic light scattering (3D LS) as well as diffusing wave spectroscopy (DWS) can cover a much extended range of experimental parameters ranging from dilute polymer solutions, colloidal suspensions to extremely opaque viscoelastic emulsions.

This paper discusses the improvement of peak resolution of static light scattering particle size measurement by application of modern iterative solvers for ill-posed problems. Static light scattering particle size measurement has many advantages such as wide range, short measurement times, and large number of measurable particles. However, the ability to separate a mixture of two different sized particles is limited. For example, if a sample contains similar sized (about 2:1 or lower ratio of particle sizes) particles, there is a possibility to fail to resolve individual peaks. That is, the obtained distribution will have one peak instead of the expected two. To overcome this disadvantage, we investigated the iterative solvers. In recent years, a number of algorithms for illposed inverse problems have been developed. We tested such algorithms by numerical simulations. In this computing experiment, the MRNSD method showed high resolution for single peak mixture samples. Finally, we measured a mixture of two sizes of polystyrene latex (PSL), 1.6 micron and 3.0 microns and a mixture of three sizes of PSL, 1.6 micron, 3.0 micron and 6.0 micron by light scattering and analyzed the data with the MRNSD method. We also analyzed the samples by image analysis and compared the results.

It is important to understand the mechanism of mixing and atomization of the diesel spray. In addition, the computational prediction of mixing behavior and internal structure of a diesel spray is expected to promote the further understanding about a diesel spray and development of the diesel engine including devices for fuel injection. In this study, we predicted the formation of diesel fuel spray with 3D-CFD code and validated the application by comparing experimental results of the fuel spray behavior and the equivalence ratio visualized by Layleigh-scatter imaging under some ambient, injection and fuel conditions. Using the applicable constants of KH-RT model, we can predict the liquid length spray on a quantitative level. under various fuel injection, ambient and fuel conditions. On the other hand, the change of the vapor penetration and the fuel mass fraction and equivalence ratio distribution with change of fuel injection and ambient conditions quantitatively. The 3D-CFD code used in this study predicts the spray cone angle and entrainment of ambient gas are predicted excessively, therefore there is the possibility of the improvement in the prediction accuracy by the refinement of fuel droplets breakup and evaporation model and the quantitative prediction of spray cone angle.

Monte Carlo modeling of light transport in multi-layered tissues (MCML) has been used for simulating light transport in human skin layers. The Monte Carlo simulations can perform ray tracing of light on the basis of optical energy. A hybrid simulator combining MCML with Mie scattering theory (HMCS) has been developed in this study to analyze light propagating in human skin on the amplitude basis. The HMCS and MCML are compared in terms of diffused light intensity profile in the skin surface and photon fluence in the penetration for the three-layered model of skin tissue.

The vector ray tracing (VRT) model is used to simulate the optical caustic structures near the primary and the secondary rainbow angles of oblate water droplets. The evolution process of the optical caustic structures in response to shape deformation of the water droplet is discussed. The dependence of the caustic structures on equatorial radius, refractive index and aspect ratio of the droplet are studied and the curvatures of the two rainbow fringes are calculated.

A novel numerical technique is presented to calculate the T-matrix for a single particle through the use of the volume integral equation for electromagnetic scattering. It is based on the method called Coupled Dipole Approximation (CDA), see O. J. F. Martin et al.¹. The basic procedure includes the parallel use of the Lippmann-Schwinger and the Dyson equations to iteratively solve for the T-matrix and the Green’s function dyadic respectively. The boundary conditions of the particle are thus automatically satisfied. The method can be used for the evaluation of the optical properties (e.g. Müller matrix) of anisotropic, inhomogeneous and asymmetric particles, both in far and near field, giving as output the T-matrix, which depends only on the scatterer itself and is independent from the polarization and direction of the incoming field. Estimation of the accuracy of the method is provided through comparison with the analytical spherical case (Mie theory) as well as non-spherical cubic ice particles.

Drop-sizing is indispensable in research and development of spray systems. Unfortunately, the commercial drop-sizing devices are generally expensive. Cheaper devices would be helpful for the researches on their beginning stage. One of the authors developed the simple system of drop-sizing and has been opened for academic researchers. The system was based on the laser diffraction method using an image sensor for obtaining the angular distribution of scattered lightintensity from droplets. But the system had several imperfections. They were basically owing to the shortage of lightintensity dynamic-range of the image sensor. The system was improved much by putting a small circular awning on the image sensor. The newly developed system is outlined, and the results of trial measurements are presented in this paper.

Fuel volatility has a great effect on its evaporation processes and the mixture formation and thus combustion and emissions formation processes in internal combustion engines. To date, however, instead of the actual gasoline or diesel fuel, many researchers have been using single-component fuel in their studies, because the composition of the former is too complicated to understand the real physics behind the evaporation and combustion characteristics. Several research groups have reported their results on droplets evaporation in a spray of multi-component fuel, carried out both numerically and experimentally. However, there are plenty of difficulties in quantitative determination of vapor concentration and droplet distributions of each component in a multicomponent fuel spray. In this study, to determine the vapor phase concentration and droplet distributions in an evaporating binary component fuel spray, a laser diagnostics based on laser extinction by droplet scattering and vapor absorption was developed. In practice, measurements of the vapor concentration distributions of the lower (n-tridencane) and higher (n-octane) volatility components in the binary component fuel sprays have been carried out at ambient temperatures of 473K and 573K, by substituting p-xylene for noctane or α-methylnaphthalene for n-tridecane. p-Xylene and α-methylnaphthalene were selected as the substitutes is because they have strong absorption band near 266nm and transparent near 532nm and, their thermo-physical properties are similar to those of the original component. As a demonstration experiment, vapor/liquid distribution of the lower boiling point (LBP) and higher boiling point (HBP) components in the binary component fuel spray have been obtained.

The effect of biodiesel produced from waste cooking oil (WCO) on the particulate matters (PM) of a direct injection (DI) diesel engine was experimentally investigated and compared with commercial diesel fuel. Soot agglomerates were collected with a thermophoretic sampling device installed in the exhaust pipe of the engine. The morphology of soot particles was analyzed using high resolution transmission electron microscopy (TEM). The elemental and thermogravimetric analysis (TGA) were also conducted to study chemical composition of soot particles. Based on the TEM images, it was revealed that the soot derived from WCO biodiesel has a highly graphitic shell-core arrangement compared to diesel soot. The mean size was measured from averaging 400 primary particles for WCO biodiesel and diesel respectively. The values for WCO biodiesel indicated 19.9 nm which was smaller than diesel’s 23.7 nm. From the TGA results, WCO biodiesel showed faster oxidation process. While the oxidation of soot particles from diesel continued until 660°C, WCO biodiesel soot oxidation terminated at 560°C. Elemental analysis results showed that the diesel soot was mainly composed of carbon and hydrogen. On the other hand, WCO biodiesel soot contained high amount of oxygen species.

In order to clarify the effect of high-pressure injection on soot reduction in terms of the air entrainment into spray, the air flow surrounding the spray and set-off length indicating the distance from the nozzle tip to the flame region in diffusion diesel combustion were investigated using 300MPa injection of a multi-hole injector. The measurement of the air entrainment flow was carried out at non-evaporating condition using consecutive PTV (particle tracking velocimetry) method with a high-speed camera and a high-frequency pulse YAG laser. The set-off length was measured at highpressure and high-temperature using the combustion bomb of constant volume and optical system of shadow graph method. And the amount of air entrainment into spray until reaching set-off length in diffusion combustion was studied as a factor of soot formation.

Application of microwave irradiation for chemical processes, such as emulsification and polymerization, has been reported [1,2]. Surfactant free emulsion can be produced with the help of microwave irradiation. Surface tension is an important property for the industrial process such as foaming/defoaming, wetting/dewetting and flotation. Similarly, the interfacial tension plays crucial role in separation and mixing process of two immiscible liquids, which are important unit operations of the fundamental chemical engineering. In practice, surface and interfacial tensions are often altered by introducing surfactants. In our previous research [3,4], specific property for surface tension of water droplet with salt under microwave radiation was found. For example, lower surface tension after the radiation was measured. The formation of nano-bubble will explain this behavior. Normally, the surface tension of aqueous solution increases with the salt concentration because cation and anion collect water molecule more strongly as a solvation. However, the exact mechanism of surface tension reduction by microwave radiation is not clear. We tried not only measurement of surface tension but also convection in the droplet during microwave radiation. This study investigates the influence of microwave on surface tension of aqueous solution. Moreover, relation between the concentration, temperature and droplet shape, which are related with surface tension.

The acquired images of interferometric particle sizing techniques are characterized by intense fringe pattern overlapping in dense droplet and bubble areas, which hinders the image processing process and subsequent information extraction. Methods employed, such as thresholding and the Hough transform and template cross-correlation, exhibit weaknesses when processing such dense areas of interest. We investigate the viability of applying the wavelet transform (WT) for the detection of the fringe pattern centers and the evaluation of the particle size. We present the basics of the WT using the Mexican hat, which exhibits excellent localization properties and present two different alternatives routes in detecting the fringe patterns in the compressed and uncompressed fringe pattern cases. We found that in comparison to the most reported methods for image evaluation, such as intensity thresholding and plain cross-correlation, the WT is a very efficient tool for detecting the patterns, even in images with high-number fringe pattern areas. The usage of the WT for the sizing of the imaged droplets and bubbles is also examined, in comparison to the Fast Fourier Transform (FFT).

In this study, microwave irradiation is applied to a liquid droplet and the surface tension, the circulation flow and temperature of water droplet are measured dynamically under the irradiation. The droplet was allowed to return to its original temperature after the irradiation, it was found that water surface tension remained well below its original value for an extended period of time. Surface tension reduction shown similar effect of ”impurity“ at molecular level during the microwave, and some “memory” after microwave, which might be caused by nano-bubble. On the other hand, microwave can introduce the circulation flow of higher rotation speed and will be expected to be applied for non-contact stirring method.

Introducing water into spray combustion systems, by either water-in-oil emulsification or supplementary water injection, is one of the major techniques for combustion improvement and NO_x reduction. Plentiful researches are available on combustion of water-in-oil emulsion fuel drops. The emulsified liquid is a heterogeneous mixture of immiscible liquids. One component forms the continuous phase and the other component forms the discrete phase. The discrete phase consists of globules of the one fluid that are suspended in the continuous phase fluid. Water-in-oil emulsions are commonly considered for combustion applications because emulsions can result in micro-explosion, thereby reducing the average drop diameter to enhance liquid vaporization, and suppressing the formation of soot and NO_x. However, the water addition generally does not exceed about 20% for smooth engine operations[!, 21. The combustion characteristics and micro-explosion of emulsion drop were studied by many researchers. The micro-explosion of water in fuel emulsion drops was caused by very fast growth of superheated water vapor bubbles, its superheat limits must be lower than the boiling point temperature of the fuel. These bubbles were primarily governed by the pressure difference between the superheated vapor and the liquid, and by the inertia imparted to the liquid by the motion of the bubble surface[3 6 In this study, we used a coaxial nozzle to generation the multi-component drop. The different type of water-in-oil fuel drops called the compound drops. Unlike an emulsion drop, a compound drop consists of a water core and a fuel shell, which can originate from the phase separation of emulsion[7, 81 or a water drop colliding with a fuel drop[9, 101 Burning and micro-explosion of compound drops have been found to be distinct from those of emulsion drops[9-111 Wang et al.[9 , 101 studied the combustion characteristics of collision merged alkane-water drops. The merged drops appeared in adhesive and inserted manners. The drop ignition delay time increased with increasing water content. The average burning rate of alkane-water drops decreased with increasing water content. In the burning process, hexadecane-water drops exhibited flash vaporization or flame extinction. Heterogeneous explosion was occasionally observed in drops with trapped air bubbles. The air bubbles were assumed to be the nucleation points of the heterogeneous explosions. Chen and Lin[11 studied the characteristics of water-in-dodecane compound drop with different water content, diameter of drop and environmental oxygen concentration. The vaporization rate increased with increasing environmental oxygen concentration. The compound drops micro-exploded during the burning process in a random way. The number of micro-explosions was majorly influenced by drop diameter, followed by environmental oxygen concentration. Water content had a weaker effect on micro-explosion. As available literature and research results of compound drop burning are scarce, their combustion and micro-explosion behaviors are still poorly understood. In this regard, we changed the drop nature as compound drops to study their combustion characteristics and micro-explosion phenomena.

In this study we introduce the time-shift technique, also known as the pulsed-displacement technique, as a means of measuring size and velocity of spherical particles. The measurement technique is not new, it has been introduced by Semidetnov^[1] in 1985 and more generally discussed by Hess and Wood^[2], Lin et al^[3], Damaschke et al.^[4] and Albrecht et al^[5]. The novelty introduced in this study is the application of the technique to measure non-transparent particles, which are quite common for example in spray drying processes or in paint sprays. In this contribution the basic working principle of the time-shift technique will be reviewed and an optical configuration suitable for the measurement of non-transparent droplets will be presented. The signal generation and processing will be discussed. Example measurements in a milk spray are presented.

High-sensitivity low-coherence dynamic light scattering (LC-DLS) is a powerful technique for measuring particle sizes in dense suspensions without the need for dilution. We have developed an LC-DLS system with a single-mode (SM)- fiber probe system and small container that can be used to hold samples of 10μL in volume. The system can be applied to lysozyme of a few nm in diameter. We have developed an angle-resolved SM-fiber probe system that is able to identify particle motion type and we verified our design by identifying the diffusion modes of particles in a polystyrene suspension.

High-sensitivity low-coherence DLS apply to measurement of particle size distribution of pigments suspended in a ink. This method can be apply to extremely dense and turbid media without dilution. We show the temporal variation of particle size distribution of thixotropy and sedimentary pigments due to aggregation, agglomerate, and sedimentation. Moreover, we demonstrate the influence of dilution of ink to particle size distribution.

We report the work in progress to develop a non invasive and fast optical method allowing characterizing the concentration, aspect ratio and mean size of acicular, nanorod and nanotube shaped particles. This method is based on the analysis of the spectral extinction of nanoparticles illuminated by polarized-light and whose orientation can be controlled by means of electrostatic and/or hydronamical forces. T-Matrix calculations and preliminary experimental results illustrate some aspects and features of this method.

Nanoparticle sizing is the most fundamental measurement for producing nanomaterials, evaluation of nanostructure, and the risk assessment of nanomaterials for human health. Dynamic light scattering (DLS) is widely used as a useful and convenient technique for determining nanoparticle size in liquid; however, the precision of this technique has been unclear. Some international comparisons are now in progress to verify the measurement accuracy of nanoparticle sizing, as a typical example of Asia Pacific Metrology Programme Supplementary Comparison. In this study, we evaluated the precision of DLS technique for nanoparticle sizing and estimated the uncertainty of the DLS data for polystyrene latex suspensions. The extrapolations of apparent diffusion coefficients to infinite dilution and to lower angles yielded more precise values than those obtained at one angle and one concentration. The extrapolated particle size measured by DLS was compared to the size determined by differential mobility analyzer (DMA), atomic force microscopy (AFM), and scanning electron microscopy (SEM). Before the comparison, the intensity-averaged size measured by DLS was recalculated to the number-averaged size, and the thickness of water layer attaching on the surface of particles were added into uncertainty of particle sizing by DLS. After the recalculation, the consistent values of mean particle diameter were obtained between those by DLS and by DMA, AFM, and SEM within the estimated uncertainties.

This paper describes a 2D detection method of single metal nanoparticles based on photothermal effect. Recently, it has been recognized that in order to utilize metal nanoparticles for optical labels, a real-time 2D detection method of individual metal nanoparticles is desirable. Metal nanoparticles can be detected by the photothermal effect, which is converting light energy to thermal energy, and localized surface plasmon resonance (LSPR). The photothermal effect induced by LSPR makes it possible to magnify an image of individual nanoparticles apparently. Its image can be detected using a single element interferometer for robust detection and performing phase analysis using the Fourier transform method for real-time detection. This paper reports that the phase of interference fringe shifted by the photothermal effect and LSPR was obtained by use of single element interferometer and the Fourier transform method. Furthermore, measuring phase shift induced by photothermal effect and LSPR, locations of single gold nanoparticles were detected by time-resolved phase measurement.

Aerosol component analysis methods for characterizing aerosols were developed for various types of lidars including polarization-sensitive Mie scattering lidars, multi-wavelength Raman scattering lidars, and multi-wavelength highspectral- resolution lidars. From the multi-parameter lidar data, the extinction coefficients for four aerosol components can be derived. The microphysical parameters such as single scattering albedo and effective radius can be also estimated from the derived aerosol component distributions.

AIST proposes new technology of non-contact transport device utilizing Coanda effect. A proposed non-contact transport device has a cylindrical body and circular slit for air. The air flow around non-contact device is turbulent and its flow pattern depends on the injection condition. Therefore we tried visualization of the air flow around non -contact device as the first step of PIV measurement. Several tracer particles were tried such as TiO₂ particles, water droplets, potatoes starch, rice starch, corn starch. Hot-wire anemometer is employed to velocity measurement. TiO₂ particles deposit inside of a slit and clogging of a slit occurs frequently. Potato starch particles do not clog a slit but they are too heavy to trace slow flow area. Water droplets by ultrasonic atomization also deposit inside of slit but they are useful to visualize flow pattern around a non-contact transport device by being supplied from circumference. Coanda effect of proposed non-contact transport device was confirmed and injected air flow pattern switches by a work. Air flow around non-contact trance port device is turbulent and its velocity range is wide. Therefore flow measurement by tracer part icle has traceability issue. Suitable tracer and exposure condition depends on target area.

The phase transformation and hydration of the NaBr and mixed NaBr and Mg(NO₃)₂･6H₂O particle were investigated in a electrodynamic balance (EDB), in which a levitated single particle of diameter about 10-50μm is in dynamic equilibrium with water vapor under controlled conditions. Raman spectroscopy was used to observe the phase transitions in an electrodynamically levitated microparticle. For the deliquescence-mode experiments of a NaBr particle, two steps with a rapid increase of particle mass were corresponded to two phase transitions from NaBr anhydrate particle to the dihydrate solid particle and from the dihydrate to the aqueous solution droplet respectively. In crystallization mode experiments, the NaBr solution droplet recrystallized as the stable anhydrate. In the case of the mixed particle of NaBr and Mg(NO₃)₂･6H₂O, ion exchange reaction took place during the deliquescence-crystallization experiment and the mixed particle of NaNO₃ and MgBr₂･6H₂O was fully formed upon efflorescence.

Control of transport and deposition of charged aerosol particles is important in various manufacturing processes. Aerosol visualization is an effective method to directly observe light scattering signal from laser-irradiated single aerosol particle trapped in a visualization cell. New single particle trap system triggered by light scattering pulse signal was developed in this study. The performance of the device was evaluated experimentally. Experimental setup consisted of an aerosol generator, a differential mobility analyzer (DMA), an optical particle counter (OPC) and the single particle trap system. Polystylene latex standard (PSL) particles (0.5, 1.0 and 2.0 μm) were generated and classified according to the charge by the DMA. Singly charged 0.5 and 1.0 μm particles and doubly charged 2.0 μm particles were used as test particles. The single particle trap system was composed of a light scattering signal detector and a visualization cell. When the particle passed through the detector, trigger signal with a given delay time sent to the solenoid valves upstream and downstream of the visualization cell for trapping the particle in the visualization cell. The motion of particle in the visualization cell was monitored by CCD camera and the gravitational settling velocity and the electrostatic migration velocity were measured from the video image. The aerodynamic diameter obtained from the settling velocity was in good agreement with Stokes diameter calculated from the electrostatic migration velocity for individual particles. It was also found that the aerodynamic diameter obtained from the settling velocity was a one-to-one function of the scattered light intensity of individual particles. The applicability of this system will be discussed.

Vertical wind speed profiles near the coast were observed using a Doppler Light Detection and Ranging (LIDAR) system at the Hazaki Oceanographical Research Station (HORS) from September 17 to 26, 2013. The accuracies of the theoretical wind profile models of the log profile model and the Monin-Obukov similarity (MOS) theory were examined by comparing them to those of the observed wind profiles. As a result, MOS, which takes into account the stability effects during wind profile calculations, successfully estimated the wind profile more accurately than the log profile model when the wind was from a sea sector (from sea to land). Conversely, both models did not estimate the profile adequately when the wind was from a land sector (from land to sea). Moreover, the wind profile for the land sector was found to include an obvious diurnal cycle, which is relevant to the stability change over land. Consequently, it is found that the atmospheric stability plays an important roll to determine the offshore wind speed profiles near the coast for not only the sea sector but also the land sector.

Various methods have been used to measure the particle size and number density of ultrafine bubbles generated by the ultrafine bubble generator, ultrafineGALF. The presence of particles with diameters of about 100 to 200 nm was indicated by every method that we used before. However, absolute identification of these as ultrafine bubbles rather than some other type of particle was not possible because conventional measurement methods using light generated by a laser and scattered by particles do not distinguish dust particles from bubbles. The present series of experiments, using the resonant mass measurement method, was the first to succeed in clearly distinguishing ultrafine bubbles from other particles. This was due to the use of the resonant mass measurement method, which is capable of distinguishing positively buoyant particles (bubbles) from negatively buoyant particles. In addition, the results from the resonant mass measurement method were compared, in terms of particle size distribution, with this from the particle tracking analysis method, which uses a different measurement principle. The particle size distributions yielded by both methods showed a moderate correlation between the number density results obtained by each.

The present study deals with, for the first time, a measurement of the number of bubbles of submicron in size before and after pressurization. Measurement of ultrafine bubbles of submicron size was conducted and it was clarified that greater number of submicron sized bubbles existed before the pressurization in comparison with that after the pressurization. The application of high pressure of gas for its dissolution into water and the ambient-pressure reduction has a possibility to increase the number of ultrafine bubbles.

In 2010, we succeeded in measuring the sizes of bubbles generated by our GALF (GAs Liquid Foam) bubble generating system, using particle tracking analysis for the first time, and quantitatively confirmed the generation and presence of ultrafine bubbles measuring around 100 to 200 nm in diameter. After that, we also developed a new technology to generate a high density of ultrafine bubbles and launched our ultrafine bubble generating system (ultrafineGALF) in 2011. This report details several independent measurements of bubbles generated in water by ultrafineGALF, using dynamic light scattering, laser diffraction scattering, particle tracking analysis, and the electrical sensing zone method. It was found that the presence of ultrafine bubbles with a diameter of about 100 to 200 nm could be determined quantitatively using any of these methods.

We have developed an ultrafine bubble generating system, ultrafineGALF, upgrading the microGALF system to a flow rate of 0.24 m³/h. The ultrafineGALF system can generate a dense population of more than 10⁹ ultrafine bubbles per ml. The density and size distribution of these bubbles have been measured using a NanoSight measuring instrument, but precision measurement of the number density has become difficult because it now extends beyond the measuring range (1×10⁹/ml) of this instrument. Thus far, the number density of the ultrafine bubbles after dilution has been measured, but few reports are available on the effect of dilution on gas particles, which behave differently from solid particles. In this study, the effect of dilution, which is required to measure the density of ultrafine bubbles at ultra-high densities, was investigated. No large differences due to the use of dilution among three types of samples with different concentrations of ultrafine bubbles were found, although the samples did show slightly different rates of change in the concentration of ultrafine bubbles over time.

Dynamics of micrometer-sized dielectric objects can be controlled by optical tweezers with scanning light, however, the trapped objects fail to track the scan when drag exceeds the trapping by too quick movement. On the other hand, optical vortices (OVs), which have a property of carrying angular momenta, can directly control torque on objects rather than their position. Laguerre-Gaussian (LG) beams are the most familiar examples of OV and have been studied extensively so far. Revolution of the objects trapped by the LG beams provides typical models of nonequilibrium statistical system, but stable mid-water trapping by the LG beams becomes essential to evaluate physical properties of the system without extrinsic hydrodynamic effects,. Nevertheless, off-axis revolutions of small objects trapped in mid-water by the LG beams have not yet been established with secure evidences. Here we report stable off-axis trapping of dielectric spheres in mid-water using high-quality LG beams generated by a holographic complex-amplitude modulation method. Direct evidence of the three-dimensional off-axis LG trapping was established via estimating the trapping position by measuring the change of revolution radii upon pressing the spheres onto glass walls. Resultantly, the axial trapping position was determined as about half the wavelength behind the beam waist position. This result provides a direct scientific evidence for possibility of off-axis three-dimensional trapping with a single LG beam, moreover, suggests applications as powerful tools for studying energy-conversion mechanisms and nonequilibrium nature in biological molecules under torque.

We have developed a new type of optical coherence tomography using visible-LED sources to investigate light propagation in a make-up skin and measure the thickness of facial foundation. The thickness is estimated by the difference between the three-dimensional tomographic images of a skin replica before and after applying facial foundation. Finally, we demonstrate experimentally that this work is the first step to investigate the relation between the appearance and the light propagation in the make-up skin.

The topographic imaging technique using a backscattered diffusing light is proposed to monitor dynamics of blood vessels depending on the blood flow as a noncontact and noninvasive method. Their depth in skin tissues can be estimated by using the relation between a spatially-integrated backscattered intensity and a probability density function of an optical path-length. The topological image of the blood vessels is obtained per 0.08 sec by the developed system.

Green emitting LiBa_1-xPO4:xTb³⁺ up-conversion phosphors with various concentrations (x=0.1, 0.2, 0.3, 0.4, 0.5) of Tb³⁺ ions were synthesized by solid state reaction method at 1300 □ for 3 hour in air. The impure phases were appeared as Tb³⁺ ion concentration was further increased (x more than 0.2). The luminescence intensity reached a maximum when the concentration of Tb3+ ion was x = 0.2, and then decreased with the increases of the Tb³⁺ concentration due to concentration quenching effect. In addition, it is identified that the d-d interaction plays a major role in the mechanism of concentration quenching of LiBaPO₄:Tb³⁺ and all the chromaticity (x, y) of LiBa_1-xPO₄:xTb³⁺ phosphors are located in the green region (0.33, 0.56 ).

Commercial laser diffraction instruments are widely used to measure particle size distribution (PSD), but the results are distorted for non-spherical (acicular) particles often encountered in practical applications. Consequently the distribution, which is reported in terms of equivalent spherical diameter, requires interpretation. For rod-like and plate-like particles, the PSD tends to be bi-modal, with the two modal sizes closely related to the median length and width, or width and thickness, of the particles. Furthermore, it is found that the bi-modal PSD for at least one instrument can typically be approximated by a bi-lognormal distribution. By fitting such a function to the reported distribution, one may extract quantitative information useful for process or product development. This approach is illustrated by examples of such measurement on industrial samples of polymer particles, crystals, bacteria, and clays.

Printed substrates are manufactured in clean environment to avoid defective productions caused by particle contaminations. However, since area of substrate has become very large in recent years, and the control of surface cleanliness is getting more difficult. In the previous work, the particle detection method in a large surface area of the glass substrate was developed with a simple system using a single-lens reflex digital camera. And the possibility of refractive-index calculation by scattered light of particles from the multi-directions measurement was shown. In this work, in order to utilize the luminance data and the coordinates of the particles obtained by the multi-directional measurement, the particle coordinate transformation and matching methods were studied. This study suggested the particle coordination matching method using OPM algorithm was applicable for detection of particle on the printed substrate. Using this method, particles on substrate surface could be identified using by particle coordinates and luminance acquired by the multi-direction.