Papers by Keyword: Focusing

Abstract: Neutron beam is a very useful probe for material characterization and non-destructive testing. There are a number of plans to construct neutron instrumens using focusing mirror to improve beam quality with higher intensity and smaller spot size. In this paper, an ellipsoidal mirror made by a metal substrate is proposed. As the metal substrate, electroless nickel is adopted because of its amorphous structure, machinability and relatively large critical angle of neutron reflection. The design of ellipsoidal neutron focusing mirror is made by considering the neutron reflectivity. A mirror is fabricated by ultrahigh precision cutting and 1^st polishing process, and the form accuracy of 5 μm P-V with surface roughness of 0.7 nm Ra is obtained. Through this experimental fabrication, the feasibility of the proposed method is verified.

Abstract: A new high-precision method to orient the ultrasonic linear array signals was proposed in this paper. First, the FastICA algorithm was used to de-noise the ultrasonic linear array signals; then the TCT algorithm is used to focus the ultrasonic linear array signals to greatest extent to cumulate the position information of broadband signals, the FastDOA is used to estimate the direction-of-arrival (DOA) of focused narrowband signals to speed up the calculation after focusing; Then, the application of partial discharge detection using this method was studied, the estimated accuracy of the method was simulated with different SNR(Signal to Noise Ratio) at first, the results show that the errors of DOA were about 2°;At last, the results from some experiments show that the errors were about 3.5°, which indicates that this estimation method is with a good accuracy.

Abstract: A TR and ultrasonic focusing wheel probe is designed for some special engineering testing item. Ultrasonic TR thickness testing and focusing detection can be carried out without coupling medium. With the testing system and the probe set on a control machine car, aligned and marginal testing for steel plates quality and the thickness testing of corroded pipe wall can be accomplished by dry couple method. The processing method of detection signal and the design of peripheral circuit are also introduced in this paper.

Abstract: The purpose of this paper is to put up a device for urinary sediment detection with a homemade microscope and a CCD, and to test the feasibility of the device. In this study, we use a capillary to absorb the urinalysis control (UC) which is diluted 500 times, and drip it into a counting pool of a urinary sediment quantitative analysis board (USQAB). In this setup device, we detect 30 counting pools in this analysis board with microscopic examination in total. Further, we count the number of red blood cells (RBC) and white blood cells (WBC) of every counting pool, and calculate the average number of RBC and WBC of 30 counting pools. Though this detection device, we are able to get 30 groups of imaging results clearly while the number of RBC and WBC in each counting pool fluctuates around the mean value. The result indicates that the setup detection device in this experiment is simple and feasible.

Abstract: A collimator is one of the most popular optical instruments used in optical workshop and parallelism of the beams is the key technical indicator of collimator. A great deal of efforts has been expended to ensure reticle locate at the focal plane. In this paper, a new laser differential confocal collimator alignment method is proposed for precision alignment of collimators. Based on this principle an experimental setup is built up and used to align two collimators whose focal lengths are 600mm and 1000mm and f-numbers are both 10.The wave-front parallelism error of the laser differential confocal system and the tested collimator is measured by the verified experiment based on scanning penta prism method. At last some influence factors alignment precision is analyzed. Theoretical analysis and experimental results show that the alighment precision based on laser differential confocal method can reach to 0.004mm.and can be a high-efficiency approach to align collimators, especially in industry production.

Abstract: The performance improved of focusing deep hyperthermia inductive heating for breast cancer treatment using magnetic fluid nanoparticles with magnetic shielding system has been presented in the paper and the results are discussed. It is a technique challenge in hyperthermia therapy is to control locally heat the tumor region up to an appropriate temperature to destroy cancerous cells, without damaging the surrounding healthy tissue by using magnetic fluid nanoparticles and cylindrical metal shielding with aperture. We show that the magnetic field intensity can be controlled by changing the aperture size to suitable. In addition, the position of the heating can be controlled very well with the magnetic fluid together with shielding system. In the simulation, the inductive applicator is a ferrite core with diameter of 7 cm and excited by 4 MHz signal. Results have shown that the temperature increments depend on the magnetic fluid nanoparticles. In addition, the magnetic field intensity without damaging the surrounding healthy tissue when used magnetic shielded system. These results demonstrate that it is possible to achieve higher temperatures and to focus magnetic field intensity where the nanoparticles and magnetic shielding system are used.

Abstract: Nowadays, the high-speed economic development has caused significant consumption of energy. While the circumstance is getting severer, solar energy is taken as a kind of clean, environmental friendly resource with infinite storage that has aroused a wide public concern. Photovoltaic and solar thermal are two main categories of solar applications. Because of its high conversion efficiency, low emission and flexible installation, dish Stirling solar power technology is more preferable to be used among the solar thermal area. From the view of practical engineering application, this paper illustrates multiple focusing methods of the current dish Stirling solar power systems in detail, and the comparison of these methods are given to analyze their advantages, disadvantages and their application scenarios. It can be used for the future development of dish Stirling solar power technology and applied as a reference for large dish solar thermal power plants’ installations and tests.

Abstract: Focusing neutron beam with wide wavelength range is an indispensable technique used to compensate for weak signals from tiny samples in various experiments using pulsed neutron beam generated from high intensity proton accelerator facilities, such as J-PARC. Aspherical supermirror device is one of the most effective optical devices for focusing neutron beam with wide wavelength range since it has no chromatic aberration. Stack of aspherical supermirror enables us to focus neutron beams with wide divergence. Thin mirrors with a millimeter thickness are required to minimize the absorption loss of incident neutron beams since the thickness of a mirror shadows the reflective area of the other mirrors. Previously, we developed a fabrication process of a precise millimeter-thick elliptical supermirror. This process consists of noncontact figuring by the numerically controlled local wet etching technique, the finishing of surface without degrading mirror shape by low-pressure polishing, and the ion beam sputter deposition of NiC/Ti multilayers on both sides of the mirror substrate to compensate for film stress. In this paper, we report fabrication of elliptical supermirror with a thickness of 1 mm and development of multiply-arranged neutron focusing mirror device using stacked 4 fabricated elliptical supermirror with a thickness of 1mm.

Abstract: In order to control the focal plane and guarantee the imaging quality of space camera, the focusing system was proposed. Firstly, the reasons of defocusing were analyzed and a solution method was given. Secondly, the system structure and operating principle were introduced. Thirdly, the system design was presented in detail. Finally, the system was experimented. Experimental results indicate that the defocusing amount of camera can be controlled below 10 um and the focusing system satisfies the requirement of system design.

Abstract: Aspherical supermirrors are some of the most useful neutron-focusing optics. We aim to develop multiple aspherical supermirror devices using high-precision figured aspherical focusing supermirrors to focus neutron beams with high intensities, because multiple mirrors collect a very large beam divergence. Thin mirrors with millimetre thickness are required to minimize the absorption loss of incident neutron beams since the thickness of a mirror shadows the reflective area of other mirrors. However, it is difficult to fabricate thin mirror substrates with a form accuracy at the sub-micrometre level by conventional machining. Conventional machining deforms a substrate by machining force and spring back after machining causes figure error. Furthermore the deposition of supermirrors deforms the mirror substrate by film stress. Thus, we developed a new process of fabricating a precise millimetre-thick elliptical supermirror. This process consists of non-contact figuring by the numerically controlled local wet etching technique, the minimization of surface roughness without degrading form accuracy by low-pressure polishing with a polishing pressure less than about 7 kPa (1psi), and the ion beam sputter deposition of NiC/Ti multilayers on both sides of the mirror substrate to compensate for film stress. In this paper, we report on the fabrication results of aplano-elliptical mirror substrate with a thickness of 1 mm.