基于多模二极管激光的汞气监测技术研究
发布时间：2018-09-17 07:48
【摘要】：汞是一种有毒的重金属元素,若过量排放,不仅会对工农业生产造成重大影响,还会威胁到人们的身体健康。我国汞污染较严重,并且几年前就已颁布条款控制汞的排放,所以现在对汞尤其是气态汞进行有效的监测变得越来越重要。近些年,随着光电技术的发展,很多化学监测方法逐渐被简单、高效、造价低廉的光学监测方法所取代,而在光学监测技术中,光谱学监测方法已成为主流方向。本课题主要针对元素汞,对象包括大气中和工厂排放废气中的气态汞。进行气态汞的监测,不仅有助于脱汞效率的提高,还对环境污染监测及改善有重要意义。本文提出利用可调谐多模二极管激光器倍频技术和和频技术产生中心波长253.7 nm的紫外激光的方法,结合关联光谱技术,经自动峰值检测及广义线性拟合的算法得出样品气室中的汞浓度,从而实现汞的连续监测。汞的吸收谱线很窄,对253.7 nm波长的光有强吸收。在倍频实验中,可调谐多模绿光二极管激光的中心波长为505 nm。通过电流和温度的控制,并在加外腔的情况下可将其波长调至507.3 nm,由BBO晶体的倍频效应得到253.7 nm的紫外光。经计算得到,合成紫外光强度为16.6 nW,且在1 m路径,4 s积分时间下,汞浓度测量灵敏度达到0.07μg/m~3,且汞浓度测量线性动态范围大约是0~45μg/m~3。最后对该系统的气体选择性和实用性进行了测试并完成了汞浓度的连续监测。在和频实验中,应用中心波长在687 nm的可调谐多模红光二极管激光器和中心波长在401 nm的可调谐多模蓝光二极管激光器,经BBO晶体产生和频效应进而获得253.7 nm的紫外光,并分别在红光和蓝光激光器上施加扫描信号,进行双路扫描。经计算得到,合成紫外光强为1.0 nW,在1 m路径,10 s积分时间下,汞浓度测量灵敏度达到0.13μg/m~3。汞浓度测量线性动态范围大约是0~36μg/m~3,并给出了线性范围与非线性范围相应的解析式。通过改变两激光器温度我们对系统稳定性进行评估并完成汞的挥发与扩散的连续监测。
[Abstract]:Mercury is a toxic heavy metal element, if excessive emissions, not only will have a significant impact on industrial and agricultural production, but also threaten the health of people. Mercury pollution is serious in our country, and some years ago, some provisions have been issued to control mercury emissions, so it is becoming more and more important to monitor mercury effectively, especially gaseous mercury. In recent years, with the development of optoelectronic technology, many chemical monitoring methods have been replaced by simple, efficient and low-cost optical monitoring methods. In optical monitoring technology, spectroscopic monitoring methods have become the mainstream direction. This paper focuses on elemental mercury, including gaseous mercury in atmospheric and factory exhaust gases. Monitoring of gaseous mercury not only contributes to the improvement of mercury removal efficiency, but also plays an important role in monitoring and improving environmental pollution. This paper presents a method of generating ultraviolet laser with center wavelength of 253.7 nm using tunable multimode diode laser frequency doubling and sum-frequency technology, combined with correlation spectroscopy. The mercury concentration in the sample chamber is obtained by the automatic peak detection and generalized linear fitting algorithm, and the continuous monitoring of mercury can be realized. The absorption line of mercury is very narrow and has a strong absorption at 253.7 nm wavelength. In the frequency doubling experiment, the center wavelength of tunable multimode green diode laser is 505 nm.. The wavelength can be adjusted to 507.3 nm, under the control of current and temperature, and the wavelength can be adjusted to 507.3 nm, under the condition of adding external cavity. 253.7 nm ultraviolet light can be obtained from the frequency doubling effect of BBO crystal. The calculated results show that the UV intensity is 16.6 nW, and the sensitivity of mercury concentration measurement is 0.07 渭 g / m ~ (-3) at 1 m path / 4 s integral time, and the linear dynamic range of mercury concentration measurement is about 0 ~ 45 渭 g / m ~ (-3). Finally, the gas selectivity and practicability of the system were tested and the mercury concentration was continuously monitored. In sum-frequency experiments, tunable multi-mode red diode lasers with central wavelength of 687 nm and tunable multi-mode blue diode lasers with central wavelength of 401 nm are used to obtain 253.7 nm ultraviolet light through sum-frequency effect generated by BBO crystal. Scanning signals are applied to red and blue lasers, respectively, and double-channel scanning is carried out. The calculated results show that the sensitivity of mercury concentration measurement is 0.13 渭 g / m ~ (-3) at 1 m path / 10 s integral time when the UV intensity is 1.0 nW,. The linear dynamic range of mercury concentration measurement is about 0 ~ 36 渭 g / m ~ (3), and the analytical formulas of linear range and nonlinear range are given. By changing the temperature of the two lasers, we evaluate the stability of the system and complete the continuous monitoring of the volatilization and diffusion of mercury.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN249;TN23
本文编号：2245209
[Abstract]:Mercury is a toxic heavy metal element, if excessive emissions, not only will have a significant impact on industrial and agricultural production, but also threaten the health of people. Mercury pollution is serious in our country, and some years ago, some provisions have been issued to control mercury emissions, so it is becoming more and more important to monitor mercury effectively, especially gaseous mercury. In recent years, with the development of optoelectronic technology, many chemical monitoring methods have been replaced by simple, efficient and low-cost optical monitoring methods. In optical monitoring technology, spectroscopic monitoring methods have become the mainstream direction. This paper focuses on elemental mercury, including gaseous mercury in atmospheric and factory exhaust gases. Monitoring of gaseous mercury not only contributes to the improvement of mercury removal efficiency, but also plays an important role in monitoring and improving environmental pollution. This paper presents a method of generating ultraviolet laser with center wavelength of 253.7 nm using tunable multimode diode laser frequency doubling and sum-frequency technology, combined with correlation spectroscopy. The mercury concentration in the sample chamber is obtained by the automatic peak detection and generalized linear fitting algorithm, and the continuous monitoring of mercury can be realized. The absorption line of mercury is very narrow and has a strong absorption at 253.7 nm wavelength. In the frequency doubling experiment, the center wavelength of tunable multimode green diode laser is 505 nm.. The wavelength can be adjusted to 507.3 nm, under the control of current and temperature, and the wavelength can be adjusted to 507.3 nm, under the condition of adding external cavity. 253.7 nm ultraviolet light can be obtained from the frequency doubling effect of BBO crystal. The calculated results show that the UV intensity is 16.6 nW, and the sensitivity of mercury concentration measurement is 0.07 渭 g / m ~ (-3) at 1 m path / 4 s integral time, and the linear dynamic range of mercury concentration measurement is about 0 ~ 45 渭 g / m ~ (-3). Finally, the gas selectivity and practicability of the system were tested and the mercury concentration was continuously monitored. In sum-frequency experiments, tunable multi-mode red diode lasers with central wavelength of 687 nm and tunable multi-mode blue diode lasers with central wavelength of 401 nm are used to obtain 253.7 nm ultraviolet light through sum-frequency effect generated by BBO crystal. Scanning signals are applied to red and blue lasers, respectively, and double-channel scanning is carried out. The calculated results show that the sensitivity of mercury concentration measurement is 0.13 渭 g / m ~ (-3) at 1 m path / 10 s integral time when the UV intensity is 1.0 nW,. The linear dynamic range of mercury concentration measurement is about 0 ~ 36 渭 g / m ~ (3), and the analytical formulas of linear range and nonlinear range are given. By changing the temperature of the two lasers, we evaluate the stability of the system and complete the continuous monitoring of the volatilization and diffusion of mercury.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN249;TN23
【参考文献】
相关期刊论文 前5条
1 乐小亮;毛慧;吴晶;刘宇麟;杨立;;高通量固定污染源废气颗粒物中总汞的测定[J];环境监测管理与技术;2015年06期
2 刘思妹;朱毅;郝睿;;国内外汞污染现状及管理措施[J];环境科学与技术;2014年S2期
3 谢伟东;王丽;陆建平;唐燕葵;;广西北部湾地区大气颗粒物中总汞的测定[J];环境科学与技术;2012年10期
4 郑徽;金银龙;;汞的毒性效应及作用机制研究进展[J];卫生研究;2006年05期
5 刘文清,崔志成,刘建国,谢品华,董凤忠,张玉钧,魏庆农;大气痕量气体测量的光谱学和化学技术[J];量子电子学报;2004年02期
相关博士学位论文 前1条
1 娄秀涛;气体监测的可调谐多模二极管激光关联光谱技术研究[D];哈尔滨工业大学;2009年
相关硕士学位论文 前1条
1 武东城;腔增强二极管激光关联光谱技术研究[D];哈尔滨工业大学;2014年
，本文编号：2245209
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