CN115931732A - Magnetic rotation spectrum multi-pass absorption cell based on steady static magnetic field and gas sensing device - Google Patents
Magnetic rotation spectrum multi-pass absorption cell based on steady static magnetic field and gas sensing deviceDownload PDFInfo
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Abstract
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Translated fromChinese技术领域technical field
本发明涉及气体检测技术领域，具体涉及一种基于稳态静磁场的双波长磁旋转光谱多通吸收池及顺磁性样品气体传感装置。The invention relates to the technical field of gas detection, in particular to a dual-wavelength magnetic rotation spectrum multi-pass absorption cell and a paramagnetic sample gas sensor device based on a steady-state static magnetic field.
背景技术Background technique
氮氧化物(NOX＝NO+NO2)的来源主要包含人类活动如化石燃料燃烧、生物质燃烧等，和自然过程如土壤中的微生物过程、野火和闪电等，其是地球对流层中的重要痕量气体，在调节大气中很多痕量气体和自由基的化学性质和生命周期方面起着至关重要的作用。基于此，高灵敏度、实时、同步检测NOx的浓度具有重要的意义。目前NOx的浓度主要通过化学发光法进行测量，但这种技术方案对其它氮化合物如过氧乙酰硝酸盐和硝酸具有交叉敏感性。同时，这种方案对NO和NO2的检测速率较慢，时间分辨率往往达到分钟量级及以上。The sources of nitrogen oxides (NOX ＝NO+NO2 ) mainly include human activities such as fossil fuel combustion, biomass combustion, etc., and natural processes such as microbial processes in soil, wildfires, and lightning, etc., which are important in the earth's troposphere. Trace gases play a crucial role in regulating the chemical properties and life cycles of many trace gases and free radicals in the atmosphere. Based on this, it is of great significance to detect the concentration of NOx with high sensitivity, real-time and synchronously. Currently NOx concentrations are mainly measured by chemiluminescence, but this technical solution has cross-sensitivity to other nitrogen compounds such as peroxyacetyl nitrate and nitric acid. At the same time, the detection rate of NO andNO2 in this scheme is relatively slow, and the time resolution often reaches the order of minutes and above.
磁旋转光谱利用在塞曼分裂吸收线附近观察到的磁圆双折射来实现对顺磁性分子的检测。在外部纵向磁场的作用下，顺磁性分子的旋转-振动跃迁会塞曼分裂成ΔMJ＝+1和ΔMJ＝-1两个分量。当线偏振光(可认为是左旋圆偏振光和右旋圆偏振光的叠加)通过浸入外部磁场的顺磁性分子时，其偏振面由于磁圆双折射而发生旋转。通过对该旋光信号的测量，可实现顺磁性分子浓度的检测。磁旋转光谱通过借助一对相互接近正交的偏振器而大幅度降低了激光强度噪声，从而显著提高了系统的检测灵敏度。此外，磁旋转光谱信号一般不会受到抗磁性分子(例如水汽和CO2)的影响，因而可实现顺磁性分子如NO、NO2等的高选择性测量。Magnetic rotation spectroscopy exploits the magnetic circular birefringence observed near Zeeman splitting absorption lines to enable the detection of paramagnetic molecules. Under the action of an external longitudinal magnetic field, the rotational-vibrational transition of paramagnetic molecules will be Zeeman-split into two components, ΔMJ =+1 and ΔMJ =-1. When linearly polarized light (which can be considered as a superposition of left-handed circularly polarized light and right-handed circularly polarized light) passes through a paramagnetic molecule immersed in an external magnetic field, its plane of polarization is rotated due to magnetic circular birefringence. By measuring the optical rotation signal, the detection of the concentration of paramagnetic molecules can be realized. Magnetic rotation spectroscopy greatly reduces laser intensity noise by using a pair of polarizers that are nearly orthogonal to each other, thereby significantly improving the detection sensitivity of the system. In addition, magnetic rotation spectroscopy signals are generally not affected by diamagnetic molecules (such as water vapor and CO2 ), so high selectivity measurement of paramagnetic molecules such as NO and NO2 can be achieved.
目前磁旋转光谱主要通过交流螺线管线圈感应电磁场，然后在单个浸入纵向磁场的腔体中实现单一组分的检测。然而在这种交流磁场中存在功耗高和发热多的局限性，同时每个腔体只能实现单一组分的检测，无法满足在单个腔体中实现多组份同步测量的需求。At present, magnetic rotation spectroscopy mainly induces electromagnetic fields through AC solenoid coils, and then realizes the detection of a single component in a single cavity immersed in a longitudinal magnetic field. However, in this AC magnetic field, there are limitations of high power consumption and high heat generation. At the same time, each cavity can only realize the detection of a single component, which cannot meet the needs of synchronous measurement of multiple components in a single cavity.
发明内容Contents of the invention
本发明要解决的技术问题为克服现有技术中的不足之处，提供一种基于稳态静磁场的双波长磁旋转光谱顺磁性样品传感装置。The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art, and provide a dual-wavelength magnetic rotation spectrum paramagnetic sample sensing device based on a steady-state static magnetic field.
本发明采用了以下技术方案：The present invention adopts following technical scheme:
一种基于稳态静磁场的磁旋转光谱多通吸收池，包括双波长多通池和设置在双波长多通池上的永磁环，所述双波长多通池包括用于形成具有容纳待测气体的气腔，和固定在所述气腔进气端的第一凹面镜、出气端的第二凹面镜，所述永磁环套设在所述双波长多通池上，并与所述双波长多通池同轴设置，所述永磁环自双波长多通池的进气端至出气端依次设置14个，每个所述永磁环的大小和形状一致，任意两个相邻永磁环的间距在0～10mm，所述永磁环排布长度与所述双波长多通池长度相适配，且自所述双波长多通池的中心分别向进气端和出气端方向呈对称排布。A magnetic rotation spectrum multi-pass absorption cell based on a steady-state static magnetic field, comprising a dual-wavelength multi-pass cell and a permanent magnetic ring arranged on the dual-wavelength multi-pass cell, the dual-wavelength multi-pass cell includes a The air cavity of the gas, and the first concave mirror fixed at the inlet end of the air cavity, and the second concave mirror at the gas outlet end, the permanent magnetic ring is sleeved on the dual-wavelength multi-pass pool, and is connected to the dual-wavelength multi-pass pool. The through pool is arranged coaxially, and the permanent magnetic rings are arranged in sequence from the inlet end to the air outlet end of the dual-wavelength multi-pass pool. The size and shape of each permanent magnetic ring are the same, and any two adjacent permanent magnetic rings The spacing of the permanent magnet rings is 0-10mm, and the arrangement length of the permanent magnet ring is adapted to the length of the dual-wavelength multi-pass cell, and is symmetrical from the center of the dual-wavelength multi-pass cell to the air inlet end and the gas outlet end. arranged.
优选的，所述第一凹面镜和第二凹面镜的中心均设置有用于连通气腔和外界进行气体交换的气孔，所述第一凹面镜和第二凹面镜上还均设置有两个与所述气孔设置位置相避让的通光孔。Preferably, the centers of the first concave mirror and the second concave mirror are provided with air holes for communicating with the air cavity and the outside world for gas exchange, and the first concave mirror and the second concave mirror are also provided with two The air holes are provided with light holes whose positions avoid each other.
优选的，所述通光孔的直径在1～3mm，位于同一凹面镜上的两个通光孔设置位置相避让，且二者不处于同一半径线上。Preferably, the diameter of the light-through hole is 1-3mm, and the two light-through holes on the same concave mirror are arranged to avoid each other, and the two are not on the same radial line.
优选的，所述第一凹面镜和第二凹面镜的大小相同，直径为25～60mm，曲率半径500～1000mm，所述第一凹面镜和第二凹面镜的凹面相对设置，设置间距100～500mm。Preferably, the size of the first concave mirror and the second concave mirror are the same, with a diameter of 25-60 mm and a radius of curvature of 500-1000 mm. 500mm.
优选的，所述永磁环材质为钕铁硼，永磁环的横截面和环臂的断面均为旋转对称形状，多个永磁环构成的纵向静磁场的磁场强度为100～500高斯。Preferably, the material of the permanent magnet ring is NdFeB, the cross section of the permanent magnet ring and the section of the ring arm are both rotationally symmetrical shapes, and the magnetic field strength of the longitudinal static magnetic field formed by a plurality of permanent magnet rings is 100-500 Gauss.
优选的，所述永磁环的横截面为圆形，永磁环的外直径100mm，内直径60mm，环臂的断面为矩形，环臂的厚度25mm。Preferably, the cross section of the permanent magnet ring is circular, the outer diameter of the permanent magnet ring is 100 mm, the inner diameter is 60 mm, the section of the ring arm is rectangular, and the thickness of the ring arm is 25 mm.
优选的，所述永磁环共设置14个，永磁环自双波长多通池的中心向进气端或出气端方向设置的间距依次为0，0，1，3，4，10mm，靠近双波长多通池的中心的两个所述永磁环间距离为0mm，14个永磁环构成的纵向静磁场磁场长度为386mm，磁场强度为300高斯。Preferably, there are 14 permanent magnetic rings in total, and the distances between the permanent magnetic rings from the center of the dual-wavelength multi-pass cell to the air inlet or outlet are 0, 0, 1, 3, 4, 10 mm, close to The distance between the two permanent magnet rings in the center of the dual-wavelength multi-pass cell is 0 mm, the length of the longitudinal static magnetic field formed by the 14 permanent magnet rings is 386 mm, and the magnetic field strength is 300 Gauss.
本发明还提供一种使用上述磁旋转光谱多通吸收池的传感装置，该装置包括信号源、激光源、和依次设置在激光光路上的起偏器、磁旋转光谱多通吸收池和检偏器，所述信号源通过加法器分别连接第一激光源和第二激光源，第一激光源和第二激光源的出射光由起偏器起偏后，自第一凹面镜进入所述磁旋转光谱多通吸收池，并在气腔内经过次反射后自第二凹面镜穿出，进入检偏器，所述检偏器的出光端依次设置有用于检测和采集激光旋光信号的光电探测器、锁相放大器，所述锁相放大器还与所述信号源电连接，获得参考信号。The present invention also provides a sensing device using the above-mentioned magnetic rotation spectrum multi-pass absorption cell. A polarizer, the signal source is respectively connected to the first laser source and the second laser source through the adder, the outgoing light of the first laser source and the second laser source is polarized by the polarizer, and then enters the The magnetic rotation spectrum multi-pass absorption cell passes through the second concave mirror after secondary reflection in the air cavity and enters the polarizer. A detector and a lock-in amplifier, the lock-in amplifier is also electrically connected to the signal source to obtain a reference signal.
优选的，所述起偏器和检偏器成对设置，包括与第一激光源对应的第一起偏器、第一检偏器，与第二激光源对应的第二起偏器、第二检偏器，所述第一起偏器与第一检偏器偏振面之间的相对偏转角度为θ1，第二起偏器与第二检偏器偏振面之间的相对偏转角度为θ2，θ1和θ2均满足80°＜θ＜100°，且θ≠90°。Preferably, the polarizer and the analyzer are arranged in pairs, including a first polarizer and a first analyzer corresponding to the first laser source, a second polarizer corresponding to the second laser source, a second A polarizer, the relative deflection angle between the first polarizer and the polarization plane of the first analyzer is θ1 , and the relative deflection angle between the second polarizer and the polarization plane of the second analyzer is θ2 , both θ1 and θ2 satisfy 80°<θ<100°, and θ≠90°.
优选的，所述信号源输出两路正弦波信号，并分别与加法器输出的三角波信号叠加后，输入第一激光源和第二激光源，所述两路正弦波信号之间的频率相差1～10KHz。Preferably, the signal source outputs two sine wave signals, which are respectively superimposed with the triangular wave signals output by the adder, and then input to the first laser source and the second laser source, and the frequency difference between the two sine wave signals is 1 ~10KHz.
优选的，所述激光源还包括激光控制模块，所述加法器分别与第一激光控制模块电连接控制所述第一激光源产生出射光，与第二激光控制模块电连接控制所述第二激光源产生出射光，所述激光源的调制频率大于10KHz。Preferably, the laser source further includes a laser control module, the adder is electrically connected to the first laser control module to control the first laser source to generate outgoing light, and is electrically connected to the second laser control module to control the second The laser source generates outgoing light, and the modulation frequency of the laser source is greater than 10KHz.
本发明的有益效果在于：The beneficial effects of the present invention are:
本发明利用非等间距排布的永磁环阵列感应稳态静磁场，从而在静态塞曼分裂下通过调制激光波长来有效改变磁圆双折射，最终产生法拉第旋转光谱信号。采用永磁体替代电磁感应稳态静磁场，可有效规避交流螺线管线圈感应电磁场时存在的能耗高和发热多的局限性，推动磁旋转光谱发展成为与传统直接吸收光谱、波长调制光谱功耗相当的高灵敏痕量气体检测装置。The invention utilizes permanent magnetic ring arrays arranged at non-equal intervals to induce a steady-state static magnetic field, thereby effectively changing magnetic circular birefringence by modulating laser wavelength under static Zeeman splitting, and finally generating Faraday rotation spectrum signals. The use of permanent magnets to replace the electromagnetic induction steady-state static magnetic field can effectively avoid the limitations of high energy consumption and high heat generation when the electromagnetic field is induced by the AC solenoid coil, and promote the development of magnetic rotation spectroscopy into a function comparable to traditional direct absorption spectroscopy and wavelength modulation spectroscopy. Highly sensitive trace gas detection device with comparable consumption.
偏振旋转角度Θ可以表示为Θ＝ΔnLπ/λ，其中λ为激光波长，L为线偏振光与顺磁性样品在磁场中相互作用的有效光程，Δn＝nR-nL为右旋圆偏振光与左旋圆偏振光的折射指数之差。本发明引入双波长多通池可以有效增加两束不同波段线偏振光与两种不同顺磁性样品之间的相互作用，从而放大法拉第旋转角度，提高磁旋转光谱的检测灵敏度。The polarization rotation angle Θ can be expressed as Θ=ΔnLπ/λ, where λ is the laser wavelength, L is the effective optical path of the linearly polarized light interacting with the paramagnetic sample in the magnetic field, and Δn=nR -nL is the right-handed circular polarization The difference between the refractive index of light and left-handed circularly polarized light. The introduction of the dual-wavelength multi-pass cell in the present invention can effectively increase the interaction between two beams of linearly polarized light of different wavelength bands and two different paramagnetic samples, thereby enlarging the Faraday rotation angle and improving the detection sensitivity of the magnetic rotation spectrum.
本发明提供的基于稳态静磁场的磁旋转光谱多通吸收池具有单腔双光路的特性，可满足两束不同波段的激光同时进入单个腔体中，实现两种顺磁性样品的同步检测，克服目前磁旋转光谱只能在单个腔体中检测单一顺磁性样品的缺陷。The magnetic rotation spectrum multi-pass absorption cell based on the steady-state static magnetic field provided by the present invention has the characteristics of single cavity and double optical path, which can satisfy two laser beams of different wavelength bands entering a single cavity at the same time, and realize the simultaneous detection of two kinds of paramagnetic samples. It overcomes the defect that current magnetic rotation spectroscopy can only detect a single paramagnetic sample in a single cavity.
另外，本发明中根据实验需求：激光源的波长和激光功率可根据检测样品及检测灵敏度的需要进行相应的调整；双波长多通池的光程可通过采用White池或高精细度腔增强型吸收池的形式进行优化，提高线偏振光与顺磁性样品之间的相互作用，改善检测极限；多通池凹面反射镜的优化设计可将双波长磁旋转光谱扩展为三波长(或更多波长)磁旋转光谱用于多组份顺磁性分子的同步检测；永磁体感应出的均匀磁场长度及强度可根据实际检测灵敏度的需要通过调整永磁环的数目、大小等进行相应的调整，从而满足各种检测需求。In addition, according to the experimental requirements in the present invention: the wavelength and laser power of the laser source can be adjusted according to the needs of the detection sample and detection sensitivity; the optical path of the dual-wavelength multipass cell can be enhanced by using a White cell or a high-precision cavity The form of the absorption cell is optimized to improve the interaction between linearly polarized light and paramagnetic samples and improve the detection limit; the optimized design of the concave reflector of the multi-pass cell can expand the dual-wavelength magnetic rotation spectrum to three wavelengths (or more wavelengths) ) magnetic rotation spectrum is used for synchronous detection of multi-component paramagnetic molecules; the length and strength of the uniform magnetic field induced by the permanent magnet can be adjusted according to the actual detection sensitivity by adjusting the number and size of the permanent magnetic rings, so as to meet Various testing needs.
附图说明Description of drawings
图1为基于稳态静磁场的磁旋转光谱多通吸收池的结构示意图；Fig. 1 is the schematic structural diagram of the magnetic rotation spectrum multi-pass absorption cell based on the steady-state static magnetic field;
图2为图1的侧视图；Fig. 2 is the side view of Fig. 1;
图3为本发明使用磁旋转光谱多通吸收池的传感装置的结构示意图；Fig. 3 is the structural representation of the sensing device using the magnetic rotation spectrum multi-pass absorption cell of the present invention;
图4为磁旋转光谱多通吸收池的凹面镜上形成的不同半径的同心环形光斑分布示意图；Fig. 4 is the schematic diagram of the distribution of concentric annular spots of different radii formed on the concave mirror of the magnetic rotation spectrum multi-pass absorption cell;
图5为利用本装置获得的300ppb NO2和NO的磁旋转光谱信号。Fig. 5 is the magnetic rotation spectrum signal of 300ppb NO2 and NO obtained by using this device.
图中标注符号的含义如下：The meanings of the marked symbols in the figure are as follows:
10-磁旋转光谱多通吸收池11-双波长多通池111-第一凹面镜112-第二凹面镜12-永磁环13-气孔10-Magnetic rotation spectrum multi-pass absorption cell 11-Dual wavelength multi-pass cell 111-First concave mirror 112-Second concave mirror 12-Permanent magnetic ring 13-Air hole
20-信号源20-signal source
31-第一激光源32-第二激光源33-第一激光控制模块34-第二激光控制模块31-first laser source 32-second laser source 33-first laser control module 34-second laser control module
40-光电探测器50-锁相放大器40-photodetector 50-lock-in amplifier
71-第一起偏器72-第一检偏器73-第二起偏器74-第二检偏器71 - the first polarizer 72 - the first polarizer 73 - the second polarizer 74 - the second polarizer
80-聚焦透镜80-focusing lens
具体实施方式Detailed ways
下面结合附图来对本发明的技术方案做出更为具体的说明：The technical scheme of the present invention is described more specifically below in conjunction with accompanying drawing:
如图1-2所示，一种基于稳态静磁场的磁旋转光谱多通吸收池，包括双波长多通池11和设置在双波长多通池11上的永磁环12，所述双波长多通池11包括用于形成具有容纳待测气体气腔的筒体，和固定在所述筒体进气端的第一凹面镜111、出气端的第二凹面镜112，第一凹面镜111和第二凹面镜112的凹面相对设置，第一凹面镜111和第二凹面镜112的中心均设置有用于联通气腔和外界进行气体交换的气孔13，气孔用于实现顺磁性分子如NO、NO2等的实时交换。As shown in Figure 1-2, a magnetic rotation spectrum multi-pass absorption cell based on a steady-state static magnetic field includes a dual-wavelength
第一凹面镜111和第二凹面镜112上还设置有与气孔13位置相避让的两个通孔用于光束进出，通光孔的直径在1～3mm并应大于激光光束直径，位于同一凹面镜上的两个通光孔设置位置相避让，且二者不处于同一半径线上。实际使用中，通光孔距离的设置满足在反射镜面所呈光斑不重叠。The first
所述永磁环12套设在所述双波长多通池11上，并与所述双波长多通池11同轴设置。永磁环12自双波长多通池11的进气端至出气端一字排开，共设置10～20个，每个所述永磁环12的大小和形状一致，任意两个相邻永磁环12的间距在0～10mm，所述永磁环12排布长度与所述双波长多通池11长度相等，且自所述双波长多通池11的中心分别向进气端和出气端方向呈对称排布。本发明中双波长多通池11的长度在100～500mm之间，永磁环12材质为钕铁硼，构成的磁场长度与双波长多通池11长度基本一致，构成的纵向静磁场强度在100～500高斯范围。The permanent
本发明中，双波长多通池11的第一凹面镜111和第二凹面镜112的大小相同，直径为25～60mm，曲率半径500～1000mm，第一凹面镜111和第二凹面镜112的凹面相对设置，设置间距100～500mm也即等于双波长多通池11的长度。双波长多通池11可以采用White池或高精细度腔增强型吸收池等现有的气体吸收池，但气体吸收池主体材料应使用硬塑料等非铁磁性材料，避免对永磁体12产生的磁场造成破坏。In the present invention, the first
在一个具体实施方案中，本发明提供的基于稳态静磁场的磁旋转光谱多通吸收池长386mm，共设置14个钕铁硼永磁环12，永磁环12均为圆形环，其环臂断面为长方形，单个永磁环12的外直径L2为100mm，内直径L3为60mm，环臂的厚度L4为25mm。由于环形磁体所感应的磁场强度受其轴向间距的影响，通过采用高斯计测量在不同环形磁体间距下(间距调节范围为0～10mm)所对应的磁场强度以及均匀度，确定最终环形磁体的设置间距满足：自气体吸收池11的中心向进气端或出气端方向设置的间距依次为0，0，1，3，4，10mm，靠近气体吸收池11的中心的两个永磁环间的距离为0mm。由此构成的静磁场长度约为386mm，纵向磁场强度为300高斯。双波长多通池11与环形永磁体12阵列同轴配合且长度基本一致，可使感应的静磁场有效应用于顺磁性分子的塞曼分裂。In a specific embodiment, the magnetic rotation spectrum multi-pass absorption cell based on the steady-state static magnetic field provided by the present invention has a length of 386mm, and 14 NdFeB permanent magnet rings 12 are arranged in total, and the permanent magnet rings 12 are all circular rings. The section of the ring arm is rectangular, the outer diameter L2 of a single
在实际应用中，永磁环12的数量、形状、大小可根据所需的静磁场强度以及使用的双波长多通池11的长度、直径来调整确定，形状可以是圆环形或方形或六边形等旋转对称图形，本发明不做具体限定。In practical applications, the number, shape and size of the permanent
应用上述磁旋转光谱多通吸收池的传感装置如图3所示，包括信号源20、激光源、和依次设置在激光光路上的起偏器、磁旋转光谱多通吸收池10和检偏器。The sensing device using the above-mentioned magnetic rotation spectrum multi-pass absorption cell is as shown in Figure 3, including a
本装置中，激光源设置两路，分别为第一激光源31和第二激光源32，所述信号源20通过加法器21分别电连接第一激光源31和第二激光源32。信号源20输出一路三角波信号和两路频率相差1～10KHz的正弦波信号，加法器21将三角波信号和两路正弦波信号分别叠加，并分别输至第一激光源31和第二激光源32。本发明中激光光源还包括激光控制模块，加法器21分别与第一激光控制模块33电连接控制所述第一激光源31产生的激光I，与第二激光控制模块34电连接控制所述第二激光源32产生的激光Ⅱ，由于检测的目标分子不同，激光I和激光Ⅱ具有不同的波长。In this device, two laser sources are provided, namely a
第一激光源31和第二激光源32的出射光经过起偏器起偏后，自第一凹面镜111进入所述磁旋转光谱多通吸收池10，并在气腔内经过多次反射后自第二凹面镜112穿出，进入检偏器。起偏器用于建立线偏振光，检偏器用于将线偏振光与顺磁性分子相互作用后的旋光信号转化为调制的光强变化。The outgoing light of the
本装置中，起偏器和检偏器根据激光源数量设置两组，包括与第一激光源31对应的第一起偏器71、第一检偏器72，与第二激光源32对应的第二起偏器73、第二检偏器74。In this device, the polarizer and the analyzer are set in two groups according to the number of laser sources, including the
起偏器和检偏器表面分别镀有与激光波长相对应的增透膜，且其偏转角度互相接近90°，法拉第旋转光谱信号在起偏器和检偏器完全正交时会消失。具体的，所述第一起偏器71与第一检偏器72偏振面之间的相对偏转角度为θ1，θ1可表示为ψ1＝90°-θ1，第二起偏器73与第二检偏器74偏振面之间的相对偏转角度为θ2，θ2可表示为ψ1＝90°-θ2。ψ1或ψ2的选择应满足磁旋转光谱信号的最佳信噪比，磁旋转光谱的信噪比定义为磁选光谱信号的峰值与非吸收位置数据点的标准偏差的比值，通过测量该信噪比与检偏器偏转角度ψ1或ψ2的关系，从而可确定最大信噪比时所对应的角度ψ1或ψ2，其一般在10°范围以内，因此，θ1和θ2取值为80°＜θ＜100°，且θ≠90°。The surfaces of the polarizer and the analyzer are respectively coated with anti-reflection coatings corresponding to the laser wavelength, and their deflection angles are close to 90°, and the Faraday rotation spectrum signal will disappear when the polarizer and the analyzer are completely orthogonal. Specifically, the relative deflection angle between the
第一检偏器72和第二检偏器74的出光端依次设置有用于检测和采集来自经过磁旋转光谱多通吸收池10的旋光信号的光电探测器40，和锁相放大器50。锁相放大器50同时与所述信号源20电连接，获得参考信号。检偏器和光电探测器40之间，还设置聚焦透镜80，聚焦透镜80用于寻常光的汇聚，将光电探测器40设置在聚焦透镜90的焦点处，用于更好地检测包含有顺磁性分子浓度信息的寻常光。The light output ends of the
在一个实施例中，利用本装置对NO和NO2进行定量检测，过程如下：In one embodiment, the device is used to carry out quantitative detection of NO andNO , the process is as follows:
首先根据拟实现的顺磁性分子的检测灵敏度确定双波长多通池11的基长为386mm，内径50mm，在其气腔两侧安装一对曲率半径为1000的凹面镜，且每片凹面镜上分别有两个直径为2mm的小孔，由此形成一个光程为24m的双波长多通池。凹面镜的设置可以在单个气腔内部实现双光束的多次来回反射，实现对双组分顺磁性分子的同步探测。如图4所示即为多次反射后反射镜面上形成的不同半径的同心环形光斑分布。First, according to the detection sensitivity of paramagnetic molecules to be realized, it is determined that the base length of the dual-wavelength
根据双波长多通池11的长度，设置永磁环12阵列的长度和间距，获得轴向磁场强度在300高斯左右的均匀磁场，从而建立磁旋转光谱多通吸收池10。According to the length of the dual-wavelength
信号源20分别输出一路三角波信号和两路正弦波信号，加法器21将信号源20输出的三角波信号分别和其中一路正弦波信号相加，然后分别输送进入第一激光控制模块33和第二激光控制模块34用于第一激光源31、第二激光源32的电调制。为获得NO和NO2的法拉第旋转光谱信号，激光源的输出波长分别为1875.8cm-1(5.331μm)和1613.25cm-1(6.199μm)，两路正弦波信号的频率相差10KHz，优选为20KHz和30KHz。The
第一激光源31和第二激光源32的出射光分别经过第一起偏器71和第二起偏器73后建立两束线偏振光，然后进入磁旋转光谱多通吸收池10，线偏振光通过在磁旋转光谱多通吸收池10内部多次来回反射，将其与顺磁性分子相互作用的法拉第旋转效应进行放大，然后经过第一检偏器72和第二检偏器74后将该旋光信号转化为调制的光强变化。The outgoing light of the
两个镀增透膜的CaF2聚焦透镜80分别将经过第一检偏器72和第二检偏器74后的寻常光聚焦到两个光电探测器40上，光电探测器40分别将检测到的调制的光强变化转化为电信号并分别输入与其电连接的两个锁相放大器50。锁相放大器50还接受来自信号源20输出的与两路正弦信号同频的参考信号，用于对两种顺磁性样品磁旋转光谱信号的解调。其中磁旋转光谱信号如图5所示，其包含有NO和NO2分子的浓度信息，从而可实现NO和NO2的定量检测。Two CaF2 focusing lenses 80 coated with an anti-reflection film focus the ordinary light after passing through the
以上仅为本发明创造的较佳实施例而已，并不用以限制本发明创造；尽管参照前述实施方式对本发明进行了详细的说明，本领域的普通技术人员应当理解：凡在本发明创造的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明创造的保护范围之内。The above are only preferred embodiments of the present invention, and are not intended to limit the present invention; although the present invention has been described in detail with reference to the aforementioned embodiments, those of ordinary skill in the art should understand that: Any modifications, equivalent replacements and improvements made within the principles and principles shall be included within the scope of protection of the present invention.
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