The infrared remote sensing monitoring technology based on the absorption characteristics of gas molecules can detect gas components at long distance, real-time and multi-gas simultaneously.In this paper,we present the method of ethylene gas identification based on infrared absorption characteristics and carry out the field verification experiment of ethylene gas by infrared spectrometer. The effective experimental data are processed and analyzed by differential method and correlation coefficient method. The results indicate that the method can effectively identify the gas with high accuracy, and the research results provide a new technical approach for the effectively identification of gas.
Manipulation of thermal radiation on metal materials attracted tremendous amount attentions in the past decades. In this study, we successfully designed simulated and manufactured three kinds of periodic micro-patterns on the nickel surface and realized the manipulation of the radiation spectrum and the polarization of nickel. The patterns which were applied to excite the surface plasmons were manufactured by the advanced ultrafast laser micro-machining technique. The experimental results of the thermal radiation showed good agreement with the simulation results. This low cost and designable method could pave the way for the future infrared applications.
Femtosecond (fs) laser is proved a powerful tool in the field of 3-dimensional internal micromachining inside the transparent dielectrics. There are already many types of femtosecond laser systems widely applied nowadays, among which Ti: sapphire femtosecond laser and femtosecond fiber laser are the two most frequently used typical femtosecond laser systems. However, according to our study, the differences in the laser parameters between these two femtosecond laser systems may induce significant discrepancy in manufacturing internal hollow structures inside the polymethyl methacrylate (PMMA) substrate. The experimental results show that when a 65fs laser beam is focused inside the PMMA substrate and scans a route of a straight line at an average power of 1.5W and 1 kHz repetition rate, a hollow microchannel is successfully fabricated and no melted region is found around the microchannel. However, if the PMMA substrate is constantly irradiated with the 1.5W laser pulses that generated by a 400fs femtosecond fiber laser system at a repetition rate of 100 kHz, a growing hollow cavity is observed and a melted-resolidified region is formed around the cavity. According to the numerical simulation of heat accumulation effect, we explain the ‘heat accumulation effect’ caused in the femtosecond fiber laser manufacturing and the ‘cold processing property’ of the Ti: sapphire femtosecond laser processing, respectively. These experimental and numerical results may broaden the understanding of thermal effect during the process of the femtosecond laser micromachining and provides more opportunities in the manufacturing of polymeric integrated microfluidic chip with laser direct writing technology in the future.
The purpose of this paper is to review laser trimming and precision control of alloy strip resistors, which is extensively applied for electronic vehicles and other power electronics. This mini review especially introduces the laser trimming of background, methodology, mechanism, influencing factor and main problem in details. The existing problems and the future development trend of laser trimming are also discussed.
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