We developed high-temporal-resolution, full-field optical angiography for use in vascular occlusion tests (VOTs). In the proposed method, undersampled signals are acquired by a high-speed digital camera that separates the dynamic and static speckle signals. The two types of speckle signal are used to calculate the short-time modulation depth (STMD) of each of the camera pixels. STMD is then used to realize high-temporal-resolution, full-field optical angiography. Phantom and biological experiments conducted and demonstrated the feasibility of using our proposed method to perform VOTs and to study the reaction kinetics in microfluidic systems.
A multi-wavelength null ellipsometer with variable incident angle has been developed recently. The ellipsometer consists
of five parts, mainly including a source set with three semiconductor lasers, a rotating component with step motor,
sample stage of variable incident angle, detector, and the system of computer control procedure and data processing
procedure. The light source set is composed of three semiconductor lasers at a wavelength of 635nm, 532nm, and 780nm
respectively and prisms used for dividing a beam of laser into two beams. An improved formula of ellipsometric
parameters (named psi and delta) has been adopted to obtain more accuracy data, as a quarter-wave plate at the
wavelength of 635nm is used as the compensator for the multi-wavelength null ellipsometer. In order to make the
instrument meet the need of ellipsometric parameters measurement of different types of substrate samples, a novel
iterative algorithm is presented. Experimental results show that the accuracy of the ellipsometric parameters can reach to
0.01°, and the precision of film thickness is 0.1nm.
A simulated annealing-simplex downhill hybrid algorithm is presented to solve the problems of ellipsometric data
inversion. Basing on Monte Carlo technique of simulated annealing algorithm, the hybrid algorithm uses simplex
downhill algorithm to get the local optimization and avoids the local optimization to get the global optimization by
Metropolis accepting principle, then the global optimum ellipsometric data are obtained quickly. A typical model with
single-layer absorbing film was dealt with by the hybrid algorithm and the simulated annealing algorithm respectively in
numerical simulation experiments. The results show that the hybrid algorithm is feasible, credible and ascendant in
ellipsometric data inversion. Furthermore, with the same testing conditions and inversion precision, the hybrid algorithm
can save time with two quantity degrees, so it will be found more applications in practice.
Based on the method of space filtering, a subassembly of space filter consisting of lens and filter is introduced and a conventional null ellipsometer has been improved to measure large roughness surface and film with large roughness interface. From theory, the possibility of using space filter in null ellipsometer to get ellipsometric parameters of large roughness surfaces corresponding to the smooth surface is analyzed, and primary experiment is carried out. Experiment results show that the improved null ellipsometer can obtain preferable repeatability and accuracy of optical parameters of large roughness surface and film with large roughness interface.
Total suspended particles (TSP) are one of the main atmospheric pollutants. The ingredients are very complex, mainly including black carbon (C),organic compound, inorganic compound and biologic component, which will do great harm to human's health. During environmental monitoring, the airborne suspended particle always is an index for evaluating the quality of atmosphere. In this article, possible mixture of TSP is proposed to determine its ingredients and content by photoacoustic spectroscopy. The normalized photoacoustic (PA) signal of the sulfur powder, mixtures of sulfur and black carbon in different proportions are obtained respectively. Simulation with linear equation says that the PA signal has a certain relationship with the content of sample. The normalized PA spectroscopy of various materials is acquired via examining the sample of the powder of cupric sulfate mixed with nitro compound (2, 5 -methoxybenzoic-4nitro-dehyde), Portland cement, residual particles of automobile exhaust pipe, ash of power plant's stocks. The experimental results have important reference value to the practical analysis of TSP, it also provides new possible methodology to the environmental monitoring.
A new method of double point sources interference scanning image for phase object is proposed in the paper. Based on the principle of the light interference, the expressions of the period and its displacement of the interference fringes have been deduced theoretically. The pictures of the fringes are gained by the CCD camera and the data are processed by the image processing technology. A gray-level image and a pseudo color image of the phase object are reconstructed. The scanning image intensity displayed by this method is linear to the phase. The phase accuracy could reaches π/10 ~ π/25, and the range of phase varies from 0 to 2π. The ray path of the experimental system is simple, and the operation is easy.
Air pollution monitoring is an important aspect of environmental protection. The pollutants to be detected are usually more than one in air or smoke monitoring. Researching new techniques that can meet the demand of detecting the pollutants at the same time is important and necessary. The paper researched the method of detecting multi-parameters in one optical fiber gas sensing system. The system used multi-wavelength and time division multiplex technique to detect the concentration of SO2 and NO2 simultaneously based on gas' spectra absorption principle. The light differential absorption formula was deduced. The two strong and weak absorbing wavelengths were chosen as signal and reference relatively. To every gas, optical coupler and narrow-band optical filters were used to generate signal and reference light from a high brightness LED. The central wavelength of filters is identical to the strong or weak absorption wavelength respectively. The multi-channel signals were switched to one light beam using a 4x1 optical switch controlled by computer in designed time sequence. The output light after absorbing by gas was coupled on a high sensitivity PIN detector. To achieve high detecting sensitivity, the light source was modulated by a pulse signal. The power and temperature control circuits were also used to stabilize the output power and wavelength of light source. After differential absorption process, the concentration of different gas can be deduced in one set of common optical and electrical sensing system.
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.
The measuring of geometrical profile and tread defects of wheel set is an important step for the safety of train vehicle running. The paper researched an automatic measuring system of comprehensive parameters of wheel set based on optoelectronic detecting technique. The system used precision laser displacement sensor, digital image processing and motion control technology to realize the non-contact automatic measuring of wheel set parameters. The tread and flange profile were captured using laser source and high resolution CCD sensor. The image SNR was gained through narrow band-pass optical filters which wavelength matched with laser source. In order to detect the irregular tread failures formed in running of train vehicle, the paper used precision laser displacement sensor to scan the tread and acquire the position while the wheel set was rotating slowly. The displacement data of different positions were transformed to digital image. Then digital image processing and mode recognition algorithm was used to distinguish and judge the failures. The repeatability and accuracy of the system can meet the demand of wheel set maintaining.
Based on the principles of geometry optics and photometry, the light energy propagating through optical fiber and monochromator has been analyzed respectively in the paper. The expressions of the utilization ratio of light energy for coupling between the common extended source and the fiber and the monochromator has been deduced theoretically. The relationships between the utilization ratio and relative aperture of convex lens, numerical aperture of the fiber, relative aperture of the monochromator and object distance are discussed. The experimental results are consistent with the theoretical analyses. The conclusions are useful and helpful for us to conduct optical experiments and utilize and choose extended source and convex lens when we work on the coupling system between the extended sources and optical fiber and monochromator.
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 paper researched a detecting system of wheelset based on real time image acquisition and processing. The system used linear laser diode sources to illuminate the wheel treads, and the profiles are obtained by high sensitive CCD. The paper researched the dynamic image acquisition, spatial transformation, image enhancement, image segmentation and measurement algorithms. By analyzing the geometric shape of the wheel tread profile, the parameters such as the flange height, the flange thickness, the angle of flange and the back to back distance can be deduced. Then the wearing degree of the wheel can be calculated, and the more important is that the next maintaining date can be predicted. It's crucial for the safety and stability ofrunning wheelset.
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