A double-time model software correlator with 5ns time resolution was presented. This correlator includes 12 independent linear correlators. A simple algorithm used for counting the number of photon signals and computing the correlation function on line, was complied by using the graphical programming language Labview8.2. By using of a photomultiplier tube (PMT), a National Instruments Model PXI-5152 high-speed acquisition board, a National Instruments Model PXI-8105 control system, correlation functions can be worked out in real time over time scales of 5μs and processing in blocks down to time scales of ~10ms. Its performances were tested by using polystyrene spheres and silicon dioxide spheres diluted in water. These two kinds of nanoparticles are in different sizes. The correlation functions computed indicate that our correlator is feasible to compute the correlation functions in photon correlation spectroscopy (PCS).
The real-time detection of plasma fluorescence spectrum in reaction chamber is significant for optimizing running parameters of the plasma syntonization enhanced system and finding sample reaction state. This paper present the new type detection system of fluorescence spectrum. This system applies a principle of control light beam transmitting by entrance pupil and viewing field, and rotated method of optical tube. It can monitor fluorescence spectrum of pointed position in reaction chamber. Some designed essentials about plan of detection range, position optical path and optical path of detecting plasma fluorescence spectrum in the system are introduced in detail. The system features are that it can aim at pointed positions of big luminophor and measure spectrum. It especially suit to real-time detect for plasma states in range nearly substrate holder. This system can applied in PECVD and some research as Chemiluminescence reaction chamber.
Based on the analysis of Dynamic Light Scattering(DLS) technique, and toke the measurement of SiO2 particle (size from 200nm-1300nm) using BI-200SM Goniometer as an example, this paper discussed the factors and the effects brought by these factors on measurement result. The analyzed factors include: poly of particles, inversion algorithm, irradiate time of laser on particles, surrounding temperature and the kind of liquid. Some phenomena was observed, such as: the difference among results by different algorithms changed with the change of particles' poly, the measurement result increased slightly as time went on, the size of particles increased greatly as the temperature was increased, the scattering light intensity was been depressed badly and the liquid with particles appeared unusually transparent and clean when SiO2 particles were put into ethanol.
It is very important to understand size and shape of PM2.5 (particulate matter smaller than 2.5μm in aerodynamic diameter) for further studying composition and characteristics of particulate matter in atmosphere. The PM2.5 was collected using no-filter membrane method. The PM2.5 images were observed by Differential Interference Contrast (DIC) Microscopy with 12 million pixels digital static camera, and the images with fine resolution 300nm were obtained. Some images of particles assorted by physical method were presented. In order to count and measure the particles, these images were processed by a series of methods, such as color channel extracting, contrast enhancing, background flattening, Gauss filtering, and scaling with standard objective micrometer, on the Image-Pro Plus (IPP) software platform. The design considerations of parameters in analyzing process were also discussed in detail. The statistical data of particle size and number of PM2.5 were obtained. Results show that the total number of particles <2.5μm in this measurement is made up of 97%, and 29.13% is the particles <1μm.
This paper describes a technique that inspects the dust emission volume by scattering-light energy characteristic of the dust particles. The scattering-light energy characteristic information, including total energy, peek value energy and the positions of peek value energy, are extracted from the scattering light received by a two-dimension cuneal image sensor. A common inspecting principle of dust emission volume and the two-dimension cuneal image sensor that realizes the measurement of scattering-light energy are discussed. According to the characteristic that the real part of refractive index influences less on the normalized distribution of scattering light the angle smaller than 30°, the center of a two-dimension cuneal image sensor is placed at the optical axis of focal plane of Fourier lens and is capable of receiving scattering light energy within forward angle 2.8°. Experiments were made with a simulating dust emitting experimental instrument and obtained scattering light energy characteristic information for dust emission volume 50mg, 100mg, 150mg, 200mg, 300mg, 400mg, 500mg and 600mg. We point out that dust emission volume can be inspected by scattering-light energy characteristic, and suggest that it is necessary to establish a database that shows the relationship between dust emission volume and scattering-light energy and to measure the size distribution of dust particles.
The UV fluorescence method for real-time monitoring concentration of sulfur dioxide is advanced method in the world at present. Some technical details of its sensor are interesting problems for instrument specialist and user. This paper introduces some design problems of Opto-electronic system with center wave 213.8nm of excitation light source and picking up signal over a range of wavelength 250-400nm. There problems include of spectrum optimal matching, elements characteristic, optimization of sensor system and analyze of experiment result. This research outcome will use to monitoring sulfur dioxide of smoke emitted from power plant.
The measurement of the dust emitting quantity is one of the important target in the environment monitoring of polluted sources. The design problem of measurement instrument for dust emitting quantity by light scattering principle are discussed in this paper. We have been investigated size distribution of dust particle emitting from thermal power plants. Light energy contribution of dust particle is studied by simulative experimental equipment. And we used a Self Scanning Photodiode Array (SSPA) in multi-ring cuneal to detect and transform the scattering energy and studied the influence of the size distribution of dust on scattering energy at small angle. We think that when design an instrument for dust emitting quantity by light scattering principle, we must consider that the size distribution of dust has influence on the light energy contribution and side scattering caused by small particles has influence on forward received single.
Based on the diffusion approximation theory, this paper researched quantitatively the influence of the thickness, the absorption coefficient, the scattering coefficient, and the anisotropy coefficient on the ultrashort laser pulse transmitted through turbid biological tissues. After transmitting through the turbid media, several picoseconds laser pulse will be widened by the diffusive scattering. The various medium parameters have much different influences on the intensity and shape of the transmitting ultrashort laser pulse. The paper concluded that the basic optical parameters of tissues can be acquired by analysing the pulse shape, and that the change of the pulse shape is mainly influenced by the scattering other than absorption. The research results can be used in optical diagnostics.
Different methods of optical imaging of biological media based on time-resolved and low-coherence techniques are discussed, including the use of streak camera, Kerr gate, electronic holography and the low-coherence interferometry. The time-resolved techniques use ultrashort laser pulses and the photons traveling different paths can be detected selectively because they have different time of flight. The low-coherence techniques use light sources with broad spectrum and low coherence length to achieve high resolution.