基于等离子体光谱特征的空气中激光铁块清洗的研究

Analysis of Laser Cleaning of Iron in Air Based on Characteristics of Plasma Spectra

利用高能Nd:YAG脉冲激光器产生的1.06μm激光,在空气环境下作用于带有严重锈层的铁块诱导产生等离子体,利用改进型ME5000中阶梯光栅光谱仪获得激光冲击铁块等离子体特征发射谱线.实验结果表明,由于样品中包含部分杂质,需激光连续作用且能量到达一定要求,才能与铁作用激发原子谱线;激光分解杂质后,等离子体谱相对强度明显增强,比较首次激光作用和清洗过程中的光谱图,当563.40nm波长处特征谱线强度增大443.11%时,锈蚀铁块已清洗干净,洗净率达99.84%;同时清洗过程中的谱线起伏度也明显降低.因此,分析首次激光作用和清洗中的光谱图,观察标线铁原子谱线分布及相对强度的变化,可以判断样品是否清洗干净.

The intensities of emission spectra of rusty iron plasma induced by Nd： YAG pluse laser, were experimentally studied in air atmosphere. Modified ME5000 echelle grating spectrometer coupled to intensified CCD camera was used to acquire the emission spectrum of laser-induced Fe plasma under the laser shock. The experimental results indicated that continuous laser impacts with certain energy were required to induce the Fe emission spectrum due to the existence of the impurities in the sample. The relative intensities of plasma spectra increased obviously after the impurities were decomposed during the process of laser shock. With the comparison of spectra acquired under 1st laser shock and in the cleaning process, it was shown that when the intensity of the characteristic line at the wavelength of 563.40 nm increased by 443.11%, the rusty iron was cleaned and the cleaning-ratio reached 99.84%. At the same time, the fluctuation of the spectrum decreased obviously during the cleaning. As a result, the changes of spectrum distribution and relative intensity of Fe spectrum lines could be used to judge whether the samples were cleaned or not through an analysis of the spectrum lines under 1st laser shock and those in the cleaning process.