Papers by Keyword: Laser Technology

Abstract: This work discusses the design of flexible laser micromilling technology for fast prototyping of metal oxide based (MOX) gas sensors in SMD packages as an alternative to traditional silicon clean room technologies. By laser micromilling technology it is possible to fabricate custom Micro Electro Mechanical System (MEMS) microhotplate platform and also packages for MOX sensor, that gives complete solution for its integration in devices using IoT conception. The tests described in the work show the attainability of the stated results for the fabrication of microhotplates.

Abstract: In order to improve the wear resistance of the surface of thick copperplate, A layer of Ni-Co-Cr alloy on thick copperplate surface is performed by laser –hybrid cladding process. In laser cladding processing, it is known that it is difficult to get good metallurgical bonding between the layer and copperplate. Micro-arc deposition technology is developed to get a thin alloy layer on the surface of thick copperplate, and then using laser cladding method to make thick coating. Micro organization analysis and wear resistance comparison experiments are taken to the specimen. From the microscopic structure analysis, it can be seen that the deposition and substrate form favorable metallurgy bonding, as a narrow metallurgical bonding zone, about 20μm in width. The micro- structure photos show that the coating is more compact, and crystal grains are refined grain composed of γ-Ni, Cr₇C₃ and CrB. The micro-hardness of the cladding zone is between 650HV~850HV, which is much higher than the copper substrate. Roughness measurement of the specimens shows that the cladding layer is smoother. The experiment’s result shows that laser-arc hybrid cladding can perform coating of Ni-Cr alloy, metallurgy bonding with the copperplate, on its surface.

Abstract: The use of laser cladding (LC) technology for the improvement of surface properties in various mechanical design applications has given rise to the development of application-oriented composites. The present paper furnishes relevant notes on an experimental approach to the design optimization of experiments regarding WC-Co based layers obtained by laser cladding. The current paper emphasizes the influence of parameter variation on the characteristics of the deposited layer and reports the manner in which the heat input and the laser power density influence the microstructure.

Abstract: In order to realize single longitudinal mode (SLM) output, an erbium-doped fiber (EDF) laser with fiber ring cavity is proposed which uses an un-pumped EDF saturated absorber as a SLM selector. Ring cavity length, coupler ratio and insertion loss which affect ring cavity filter performance are analyzed theoretically and simulated numerically. Un-pumped EDF length and Er³⁺ concentration are analyzed theoretically and simulated. Research shows that, the bigger coupling output ratio of ring cavity, the greater transmission peak; the greater mode line width; the shorter ring cavity length, the wider free spectral range; the bigger coupling loss, the smaller transmission peak; when the difference between two cavities length is big, cursor effect is not obvious. Laser threshold increases with absorber length increasing; the bigger saturated absorber concentration, the higher laser threshold.

Abstract: Mathematical-physical model of powder stream in coaxial powder feeding was established. The concentration fields of powder stream of coaxial nozzle of different size and powder mass flow rate were analyzed. The concentration field and morphology of the powder stream were detected by CCD camera. The results show that the size of coaxial nozzle and powder mass flow rate are major factors affecting the powder stream. The mathematical-physical model and experimental data provide theoretical basis for laser cladding manufacturing.

Abstract: We explore a simulation model of drilling micro-hole in sticking plaster heated with a dual CO2 laser beam. This paper applied numerical simulation of temperature by using finite element analysis software Ansys to study a model of drilling on sticking plaster. A dual CO2 laser spot sizes ranged from 0.15 to 0.2mm radius with axial irradiance power levels of 50-100w. For temperatures above 450°C, sticking plaster would be vaporized. The size of ventilation holes changed with beam power and laser spot diameter. The width of the hole is increases with the increasing laser diameter and with the increasing laser power. These results can guide to laser drilling experiments.

Abstract: Laser induced interstitial thermotherapy (LITT) is a useful method for the treatment of tumors. In order to control the treatment of LITT, a new local control technique has been put forward. A functional near infrared spectroscopy (fNIRS) system was used. The temperature of biological tissue is regarded as the most important indicator for treatment of LITT. So, the propagations of near infrared laser in normal tumors and liver tumors were simulated with Monte Carlo method. Based on the distribution of light in normal tumors and liver tumors, the temperature distribution inside tissue under laser irradiation has been retrieved. Furthermore, the influences of laser power and action time on the temperature field were studied. The results show that the normal tumors and liver tumors have different light absorption with laser beam. The difference of temperature distribution in tissues with the same laser power is useful to apply in control the treatment of laser-induced interstitial thermotherapy for liver tumors. It is confirmed that the fNIRS can be a useful local control technology for LITT.

Abstract: The dynamic tilting of high-precision turntable has a very significant impact on the parameters of measurement and processing during the operation.In order to achieve long-term stability and control the turntable’s dynamic tilting angle at the second level, only improving the mechanical precision of the turntable is not realistic, and it may greatly enhance the cost of the turntable. A precision turntable dynamic tilting test method based on laser and CCD technology is put forward in this paper. The system uses laser as the light source, and uses CCD image sensor to receive the reflected signal of the turntable. According to the amount movement of the laser spot on the CCD target surface and the corresponding geometric relationships, we can measure the inclination error of the turntable. During debugging analysis and practical application, it proves that the system can achieve differentiate accuracy at the second level and meet the needs of online measurement.

Abstract: This paper aimed to solve the problems that traffic detector which was used in china, can't satisfies the multifunction and high-accuracy needs of the domestic traffic survey and traffic volume measurement.We designed a traffic detection system based on laser and piezoelectric technologies,which is made up of laser speed sensor, laser scanning sensor, piezoelectric axle shaft sensor, data acquisition unit, software system and server, and their application was discussed in detail. The working principles of laser speed sensor, laser scanning sensor, piezoelectric axle shaft sensor were presented, and the detection parameters of the system were put forward. The whole structure and data processing flow of software system were also pointed out. Through test verification, the multifunction and high-accuracy characteristics of the system were verified. This traffic detection system has great significance for enhancing the research level of the domestic traffic survey and traffic volume measurement.

Abstract: The principle of laser welding of combined translucent thermoplastic and absorbance thermoplastics is that laser transmit through translucent material and shoot at laser absorptive material, where the material absorb energy and melt down to complete welding. This paper studied the applicability of basic law of laser transmission welding beam mechanism and light absorption process – Beer-Lamber Law to plastic materials. Numerical simulation model of melting depth was established. Single factor relevance curve and double factor relevance surface were drawn with MATLAB; Impact of laser power, distance between weld zone and lens and scanning speed to melting depth was quantitatively analyzed on melting depth, which provided effective reference for setting parameters in the experiment.