Evaluation and correction of laser scattering-based particle size measurements at high obscurations using the Monte Carlo method.

High turbidity and its associated multiple scattering phenomena can often lead to an underestimation of the particle size for the laser scattering method. To investigate the light scattering characteristics and evaluate the effect of high-obscuration particle systems, a Monte Carlo model has been developed based on Mie's theory. A compact setup was utilized to perform a series of experiments on three certified reference materials (CRMs) at different concentrations. Both the scattered light energy distribution and the obscuration were measured simultaneously. The inversion results of the particle size indicate a continuous increase in deviation from the nominal value as the obscuration rises. According to the conventional single scattering model, the inversion errors fall within 5% for obscuration levels ranging from 0.15 to 0.2. However, for a higher obscuration, the error can reach approximately 15%. Thus, a correction method has been proposed by introducing an improved model matrix that includes the multiple scattering contribution for the data inversion, which exhibits a significant enhancement in the accuracy of particle size measurements under high obscuration conditions. For all three types of particles being studied, the error was successfully reduced to within 5.0%.

The Development of a Novel Headspace O2 Concentration Measurement Sensor for Vials.

In the process of manufacture and transportation, vials are prone to breakage and cracks. Oxygen (O2) in the air entering vials can lead to the deterioration of medicine and a reduction in pesticide effects, threatening the life of patients. Therefore, accurate measurement of the headspace O2 concentration for vials is crucial to ensure pharmaceutical quality. In this invited paper, a novel headspace oxygen concentration measurement (HOCM) sensor for vials was developed based on tunable diode laser absorption spectroscopy (TDLAS). First, a long-optical-path multi-pass cell was designed by optimizing the original system. Moreover, vials with different O2 concentrations (0%, 5%, 10%, 15%, 20%, and 25%) were measured with this optimized system in order to study the relationship between the leakage coefficient and O2 concentration; the root mean square error of the fitting was 0.13. Moreover, the measurement accuracy indicates that the novel HOCM sensor achieved an average percentage error of 1.9%. Sealed vials with different leakage holes (4, 6, 8, and 10 mm) were prepared to investigate the variation in the headspace O2 concentration with time. The results show that the novel HOCM sensor is non-invasive and has a fast response and high accuracy, with prospects in applications for online quality supervision and management of production lines.

Development and application of an optimal three-wavelength combination for liquid film measurement with absorption spectroscopy.

In the simultaneous measurement of liquid film temperature and thickness based on multi-wavelength absorption spectroscopy, selecting optimal wavelength combinations can significantly improve the measurement accuracy. In the work, the absorption spectra of e-liquid at different temperatures were measured firstly. And ten sets of two-wavelength and three-wavelength combinations were then established based on five specific wavelengths from the absorption spectra, respectively. And the measurement accuracy of all the combinations were validated with a home-made calibration system. Among them, an optimal three-wavelength combination were selected. Finally, the evaporation processes of e-liquid films at three initial thicknesses (921/780/629 µm) on a horizontal quartz plate were then investigated with the optimal combination. The variation trends of film temperature and thickness measured by the combination were consistent with imaging method and thermocouple. It was found that the optimal three-wavelength combination could achieve high accuracy in simultaneous measurement of liquid film temperature and thickness.

On-Demand Integrated Quantum Memory for Polarization Qubits.

Photonic polarization qubits are widely used in quantum computation and quantum communication due to the robustness in transmission and the easy qubit manipulation. An integrated quantum memory for polarization qubits is a useful building block for large-scale integrated quantum networks. However, on-demand storing polarization qubits in an integrated quantum memory is a long-standing challenge due to the anisotropic absorption of solids and the polarization-dependent features of microstructures. Here we demonstrate a reliable on-demand quantum memory for polarization qubits, using a depressed-cladding waveguide fabricated in a ^{151}Eu^{3+}:Y_{2}SiO_{5} crystal. The site-2 ^{151}Eu^{3+} ions in Y_{2}SiO_{5} crystal provides a near-uniform absorption for arbitrary polarization states and a new pump sequence is developed to prepare a wideband and enhanced absorption profile. A fidelity of 99.4±0.6% is obtained for the qubit storage process with an input of 0.32 photons per pulse, together with a storage bandwidth of 10 MHz. This reliable integrated quantum memory for polarization qubits reveals the potential for use in the construction of integrated quantum networks.

Simultaneous measurement of liquid film thickness and temperature on metal surface.

The flow and evaporation of liquid films widely exist in various industrial fields. The investigation into liquid films is essential to design and optimize the relevant industrial processes. In this work, a simultaneous measurement method of liquid film thickness and temperature on metal surface based on diode laser absorption spectroscopy (DLAS) was proposed, and a corresponding measurement system was developed. First, static liquid films of 200-800 µm on the horizontal metal plate were studied, ultrasonic pulse-echo method (UPEM) and thermocouple were employed to compare with DLAS data. It revealed that the relative deviations of film thicknesses and temperatures measured by different methods were 3.3% and 2.0%, respectively. Furthermore, the evaporation processes of static liquid films were investigated. For the liquid films with different initial thicknesses (490.0/624.6/744.5 µm), the average relative deviations of the film thicknesses and temperatures measured by different methods were 0.1%/0.8%/4.1% and 0.1%/2.6%/3.0%, respectively. Finally, the flow processes of liquid films at different initial temperatures (40.0/60.0/80.0 °C) on the inclined metal plate were researched. It was found that the variation trends of the liquid film thicknesses and temperatures measured by different methods were in good agreement. In the stable stages of flow processes, the average relative deviations of liquid film thicknesses and temperatures measured by different methods were 9.0%/8.4%/5.1% and 3.6%/1.2%/2.5%, respectively. This work is helpful to understand the heat and mass transfer mechanisms in the evaporation and flow processes of liquid films.

[Observation of Aerosol Optical Properties and New Particle Formation in the Yangtze River Delta].

In a recent field campaign focused on air quality study, aerosol optical properties, particle number concentration, and PM2.5 components were monitored in Changzhou, Jiangsu Province, from May 27 to June 27, 2019. An array of instruments were deployed that included scanning mobility particle size spectrometer (SMPS), aethalometer (AE33), cavity attenuation phase shift single albedo monitor (CAPS-ALB), monitor for aerosols and gases in ambient air (MARGA) and RT-4 organic carbon/elemental carbon (OC/EC) carbon analyzer to study the ① changes in chemical composition and optical parameters of the new particles generated during the campaign period. ② comparison of the aerosol extinction coefficient recorded by these instruments and measured value in the reconstruction of IMPROVE (interagency monitoring of protected visual environment) and the calculated coefficient using MIE theory model were carried out. During the entire campaign, two new particle generation events were observed and also found that the particle size continued to increase from 4 nm to 64 nm. It was monitored that in the initial stage of new particle generation, sulfate contributed greatly. The measured average aerosol extinction coefficient during the period of particle generation, using these instruments was 95.40 Mm-1, while the average aerosol extinction reconstruction using the IMPROVE model was observed to be 140.20 Mm-1. The theoretical calculations based on Mie theory model yielded an average extinction coefficient of 93.54 Mm-1. It was found that the average aerosol extinction in Changzhou is lower than the average value of the urban aerosol extinction coefficient, which is measured to be 300 Mm-1 in China, during this period. The deployment of multiple instruments in a single campaign is more desirable because the combination of all observations helped in better characterization of the physicochemical properties of ambient aerosols from various aspects, including particle size spectrum and chemical composition.

On-Demand Quantum Storage of Photonic Qubits in an On-Chip Waveguide.

Photonic quantum memory is the core element in quantum information processing (QIP). For the scalable and convenient practical applications, great efforts have been devoted to the integrated quantum memory based on various waveguides fabricated in solids. However, on-demand storage of qubits, which is an essential requirement for QIP, is still challenging to be implemented using such integrated quantum memory. Here we report the on-demand storage of time-bin qubits in an on-chip waveguide memory fabricated on the surface of a ^{151}Eu^{3+}:Y_{2}SiO_{5} crystal, utilizing the Stark-modulated atomic frequency comb protocol. A qubit storage fidelity of 99.3%±0.2% is obtained with single-photon-level coherent pulses, far beyond the highest fidelity achievable using the classical measure-and-prepare strategy. The developed integrated quantum memory with the on-demand retrieval capability represents an important step toward practical applications of integrated quantum nodes in quantum networks.

Development of a two-line DLAS sensor for liquid film measurement.

The simultaneous measurements of multiple parameters (film thickness, temperature, etc.) of the liquid films are crucial for the design and optimization of relevant industrial processes. Here, a sensor based on diode-laser absorption spectroscopy (DLAS) was developed to simultaneously measure liquid water film thicknesses and temperatures by combining two diode lasers at different wavenumber positions, 6718.2 cm-1 and 7040.8 cm-1. Serious beam steering effects can be avoided by adding an integrating sphere to improve the performance of the sensor for the investigations of dynamic films. The measurement accuracies of this sensor were firstly validated by a calibration tool with known film thicknesses and temperatures. It revealed that the averaged deviations between the measured film thicknesses/temperatures and the corresponding known parameters were 4.58% and 1.34%, respectively. The sensor was then employed to study liquid film evaporation processes on a horizontal quartz glass plate. The imaging method and the thermocouple were simultaneously employed to obtain the film thicknesses and temperatures to compare with the DLAS results. It showed that the average evaporation rates of the liquid films were 0.34/0.41/0.57 µm/s at different temperatures (340/360/390 K) of the heat gun outlet, respectively, and the evaporation rates increased with the increasing film temperatures. The whole evaporation process can be tracked with the sensor. Furthermore, the sensor was applied to simultaneously determine the variations of liquid film thicknesses and temperatures in a flow channel. It was found that the film temperatures remained almost constant during passage of low-amplitude surface waves at the film temperatures 308/315/323 K.

Numerical prediction of ultrasonic attenuation in concentrated emulsions and suspensions using Monte Carlo method.

For the study of predicting ultrasonic attenuation of mixed particles and probing the effect of interaction between neighboring particles, the Monte Carlo method was investigated to establish a submicron particle size characterization model in concentrated particulate two-phase system and serve as a probability and statistics technique to evaluate the underlying ultrasonic events during the ultrasound propagation. The numerical simulation method was proposed to predict the ultrasonic attenuation characteristics in the two-phase system of silica suspensions and corn oil-in-water emulsions with different particle sizes, ultrasonic frequencies and concentrations. Furthermore, an extension of the well-established single-particle theory of Epstein-Carhart and Allegra-Hawley (ECAH) was carried out, by incorporated in the couple phase model from a hydrodynamic point of view and effective hypothesis both accounted for the ultrasonic wave overlapping effect for the close proximity of particles. The simulation result shows agreement with the results of the ECAH model, the Lloyd & Berry (LB) model and the Waterman model in the dilute limitation, corresponding to glass beads and silica particles respectively. Afterwards, such a method was then applied into mixed particle system, where the mixed iron particles and glass beads with various ratios were set as examples for the purpose of predicting ultrasonic attenuation for the mixed particle systems. After comparing with the experimental results, it is shown that as a function of frequency, the variation of the ultrasonic attenuation coefficient with different mixing ratio manifests a nonlinear tendency. Also noteworthy is that the physical properties of particles play a dramatic impact in influencing ultrasonic attenuation. At higher concentrations, it was validated both in two-phase system of silica suspensions and corn oil-in-water emulsions that the attenuation predicted by Monte Carlo method agreed well with the experimental results of literature, yielding a theoretically increasing but less than linear expected attenuation with particle concentration. Particularly, the critical concentration of deviation from the linear change was obtained and interpreted using the thermal and viscous overlapping theory. The proposed Monte Carlo method presents a novel approach in calculating the attenuation in high particle volume concentration of more than 40% and provides a numerical modeling of particle size measurement in the complex particle-particle interaction condition.

Simultaneous measurement of film thickness, temperature, and mass fraction of urea-water-solutions by multi-wavelength laser absorption spectroscopy.

Quantitative analysis for thickness, temperature, and mass fraction of liquid film is extremely crucial to the relevant industrial processes, but these parameters cannot be determined simultaneously by conventional measurement techniques. In the present work, a novel measurement method based on laser absorption spectroscopy was developed to measure the film temperature, thickness, and mass fraction of urea-water-solutions simultaneously by combining three wavelengths, 1420 nm, 1488 nm, and 1531 nm. Moreover, measurement accuracy of this method was validated by a calibration tool which provided liquid film with known film thickness, temperature, and mass fraction, respectively. It revealed that the deviation between the measured and known parameters with the developed method was 0.86%, 4.58%, and 3.85%, respectively.

A novel method for plastic particle sizing in suspension based on acoustic impedance spectrum.

The objective of this paper is to explore the relationship between the characteristics of plastic particles in suspension and acoustic impedance spectrum and to present a novel non-invasive methodology for both spherical and non-spherical particle sizing. By modifying the ultrasonic attenuation spectral model, theories relating acoustic impedance spectrum to particle characteristics have been established to implement quite a few numerical simulations for the first time, revealing that the acoustic impedance of plastic particles is sensitive to changes in particle concentration and size. Afterwards, experiments were carried out on polystyrene suspensions made by particles with different sizes. On the basis of the theoretical analysis, different transducers were employed over a frequency varied from 10MHz to 100MHz for different particle sizes respectively. Not only were spherical particles chosen for the experiment, but also non-spherical particles with three different size distributions considering the fact that practical particles have irregular shapes. All the samples were verified by optical microscope technique and their comparisons with the experimental results show that the plastic particles with different sizes are distinguishable by using acoustic impedance spectrum.