Papers by Keyword: Infrared Laser

Abstract: The work aim to the reaction mechanism of laser engraving polycarbonate (PC)-based films. The calculation of infrared-laser acting on the PC films, was carried out by using one-dimensional heat conduction model. The power density of laser device required for laser engraving polycarbonate-based films was determined to be 4.86~7.73×10⁴ W/cm². Characterized by the FTIR spectra, SEM, DSC and TGA, the reaction mechanism was studied. The results show that the light-sensitive particles in the PC films absorb the laser energy with wavelength of 1064nm. After reaching the temperature of 509°C, the main chain of PC molecule opened due to the breakage of C-O bond in PC molecular terminal group and C-O bond between PC monomers. As the energy continues to be absorbed, the temperature reach to 610°C, the decomposition products decomposed into carbon black, which can form a black carbon spot.

Abstract: Detection of C₂H₂ gas in transformer oil is significant for diagnosing the operating state assessment of power equipment. The paper develops an infrared laser gas sensor to detect the C₂H₂ gas in transformer oil, and also introduces the system structure in detail. A gas-absorbed laser cell that contains a series of laser reflectors is designed and used in our detection system, which adds the optical path without changing the volume of the cell. 1529.16nm is chosen as the characteristic spectrum line of C₂H₂ gas, and concentration of C₂H₂ gas is quantitatively analyzed based on least square method. The experiment result shows that in certain volume fraction range of acetylene, the absorbance has a good linear relationship with the acetylene concentration, and the minimum detection limit for acetylene is 10μL/L. In general, the developed infrared laser gas sensor can detect C₂H₂ gas in transformer oil effectively.

Abstract: In order to solve the problem that delamination and bur will be easily produced in the process of the carbon fiber reinforced plastic (CFRP) composites, the cutting experiment of CFRP machined by pulsed Nd:YAG laser has been carried out. In the meantime, this paper investigates the mechanism of interaction between infrared laser and CFRP composite material and the quality of kerf influenced by different laser parameters and cutting directions. The study found that choosing appropriate laser parameters and cutting direction are effective means to get smaller heat affected zone (HAZ). This paper analysis the cross section morphology of kerf .The results show that the cross section does not appear stratified phenomenon and the surface is smooth, so the feasibility that infrared laser can be used to cut CFRP composites is verified.

Abstract: A non-contact method of measuring the surface roughness and the thickness of polished silicon wafers using an infrared laser is proposed. The method utilizes the property that the infrared radiation is transmitted through single-crystal silicon. An optical-power meter is used to measure the intensity of an infrared laser beam that is incident to a chamfer on a cornered silicon wafer and which exits from the other side of the chamfer after repeated total reflections inside the wafer. The experimental results show that a significant correlation exists between the intensity of the transmitted infrared radiation and the surface roughness of the silicon wafers, as well as between the intensity and the thickness of the wafers. Therefore, if a calibration curve is pre-set, the surface roughness and the thickness can be estimated from the changes in the intensity of the infrared transmittance.