光谱仪基本知识分解

,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text 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level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,|,Creative ways to construct winning e-mails,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,光谱仪器的根本学问A Basic Introduction of Spectrometer Instruments,陈和 北京理工大学 光电学院,Tel：68918398,OPTICS,Spectrometer,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,色散元件,之棱镜,Prism,i,1,i,1,i,2,i,2,偏向角,为,：,对于肯定的入射角，偏向角随折射率n变化。,一般地，波长短，折射率大，偏向角大。,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,最小偏向角条件,对于,单色的入射光,，偏向角,随入射角变化而变化，对于某一个入射角，偏向角存在最小值。,i,1,i,1,i,2,i,2,i1 = i”2,此时：,i”1=i2=/2,min=2i1-,依据折射定律和几何关系可以得到最小偏向角条件：,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,最小偏向角的特点和优势,当棱镜工作在最小偏向角时，入射光和出射光是完全对称的，在棱镜内部光线平行于棱镜底边传播。,设计棱镜光谱仪器时一般使色散棱镜对某个中间波长处于它的最小偏向角位置上进展工作。,对称的光路可以使得棱镜产生的相差球差，像散最小，使得谱线成像质量好，区分率高。,光路对称时，棱镜不产生附加的横向放大率针对一个特定波长而言。,可以充分利用棱镜的有效孔径，使得尺寸最小。,对称光路便利设计使用。,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,棱镜的角色散率,依据角色散率定义，在最小偏向角状况下的棱镜角色散率为：,增加角色散率的方法：,1 减小入射角杂散光影响,2 增大折射顶角全反射限制,3 增大材料色散材料和价格限制,最常用的方法,：,增加棱镜数目。,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,棱镜的区分率,t,D,l,D,+d,d,依据角区分率公式，有：,矩孔衍射打算的最小区分角为：,最小偏向角状况,实际状况,|,Creative ways to construct winning e-mails,棱镜的横向放大率,i,1,i,1,i,2,i,2,D,D,棱镜非主截面的光谱线弯曲,狭缝的像在焦平面上不是一条直线而是一条弯曲的光谱线，弯曲的方向朝向短波方向。,缘由：非狭缝中心的光线进入棱镜时，不是通过棱镜的主截面，而是在倾斜截面上折射，此时的色散率和偏向角都和主截面上的不同。,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,棱镜可用的材料,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,例子,=400nm t=5cm,熔融石英 n=1.47，dn/d=1100cm-1,重燧石玻璃：n=1.81， dn/d=4400cm-1,考虑一等边棱镜，顶角60度，成像透镜焦距f=100mm,角色散率 ：,线色散率 ：,区分率 ：,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,几种常用的棱镜构造,Littrow 棱镜,Amici,棱镜,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,色散元件,之光栅,Gratings,光栅方程：,i和在法线的同一侧，两角度符号一样，取正号,i和在法线的不同侧，两角度符号相反，取负号,d,i,n,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,m=0，全部波长不分开，没有色散，零级光谱,m0，对于肯定的光栅常数和同样的入射角，同一级次不同波长的光在空间向左右两边分开,m0，正级光谱 m0，负级光谱,对于给定光栅的最高光谱级次限制：,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,光栅的角色散率,光栅的角色散率与光栅常数d成反比,光栅的角色散率与光谱级数成正比,光栅的角色散率与衍射角余弦成反比,在靠近法线位置：,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,光栅的区分率,则波长,+d的第m级主亮条纹,：,考虑一块抱负光栅，入射和衍射光线都位于主截面内，假设为正入射i=0，则波长的第m级主亮条纹：,波长的第m级主亮条纹外的一阶微小值满足：,瑞利判据：,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,光栅光谱的叠级和自由光谱范围,等式左边不变，右边可以是不同级次的不同波长，即,这种现象称为光谱的,叠级,。,一个光谱级中不受其他级次光谱重叠的波段称为,自由光谱范围,。,光谱叠级可以用滤光片和预色散消退。,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,闪烁光栅,原理：对于闪烁光栅，每个刻痕断面都相当于一个小反射镜，当衍射光线主要集中于反射方向上，能量可以集中在所需要的某一光谱级次的波段范围内。,n,n,i,a,d,闪烁光栅的几何参数a和需满足肯定条件：,一、反射方向与需要的衍射方向全都,二、光栅零级主极大方向在单缝的负第一衍射级的微小方向上,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,闪烁波长,对于确定的光栅，对于肯定的入射角，衍射角的方向与反射方向全都的波长，称为光栅的闪烁波长。此时的衍射角称为光栅的闪烁方向。,正如前面所示，此时要满足：,我们将刻槽面与光栅平面的夹角称为闪烁角。上式称为付闪烁条件。,此时的光栅方程：,一般规定m=1时的波长为闪烁波长b，则：,当i=时Littrow装置中，闪烁波长B为：,i=又称为主闪烁条件,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,闪烁光栅的效率,确定效率：在给定的光谱级中，衍射光的通量对入射的单色光通量之比。,光栅效率一般打算于刻槽的轮廓和密度，而且随波长变化。,光栅效率也和入射光的角度以及偏振态有关。,有用波长范围的阅历公式：,闪烁波特长，光栅效率最高，在闪烁波长的两侧效率下降。下降速度随级次增大而加快。,效率大于0.4的波长范围才被认为是有效的工作区域。,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,光栅制作的要求,依据理论计算和实际工作：,一块用于一级光谱的光栅，它的刻线随机误差和周期误差不应超过光栅常数的1%，累积误差不超过光栅常数的10%。,对应用于第m级光谱的光栅，上述误差的许可值将与光栅的光谱级次成反比。,例：,应用1级光谱的1200 L/mm光栅，随机误差和周期误差不大于0.008um，而累积误差要小于0.08um,要到达如此高的精度，技术上的难度极大。,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,光栅的制造方法,1、机械刻划,精选玻璃毛坯，真空镀膜，刻划槽型，检验,3,、全息法制造,玻璃毛坯精选和加工；涂光致抗蚀剂；曝光；化学处理；真空镀膜,2、光栅复制,母光栅清洁，真空镀油，镀铝，配制环氧树胶，毛坯清洁，粘接与固化，分别与修正,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,光栅制造中的缺陷,伴线,刻线间距的偶然的和局部的误差导致谱线轮廓外形简单化，在较高级次的光谱中，靠近谱线会消失微弱的大多不对称的伴线。,伴线相对强度较小时，并不影响区分率，但是影响谱线轮廓的争论。,鬼线,是由刻划中的周期性误差引起的，这样会在真谱线两侧产生对称的假谱线。,有罗兰鬼线和赖曼鬼线两种。,杂散光,刻划中的各种局部误差和随机误差，以及光滑度的缺乏等都会引起杂散光的存在，现在的光栅一般要求杂散光的相对强度小于10-5,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,常用光栅装置类型,Littrow李特洛装置类型,自准直构造，构造简洁，紧凑。,狭缝和光栅之间尽可能近。,用抛物面镜作反射时，可以没有球差，且慧差最小。,谱线弯曲无法消退。,杂散光比较多。,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,Ebert-Fastie(艾伯特-法斯梯)装置类型,通过扫描光栅来获得不同的波长,剩余慧差小。适用于单色仪。,光栅尺寸大的时候不能适用。,简洁产生屡次衍射。,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,Czerny-Turner(切尔尼-特纳)装置类型,此装置是Ebert-Fastier装置的改进版，避开了屡次衍射，能够适用更大的光栅，还可以更好消退球差。,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,光谱仪器设计的根本原则,1、保证仪器的各项根本性能,2、光学系统必需能保证工作要求所需的光学性能,3、仪器的最终综合误差必需在允许范围内,4、构造简洁合理，在指定环境下稳定牢靠，并有足够的寿命,5、留意制造和装调的工艺性，尽可能使用标准件,6、在设计系列化光谱仪器时，应有一统一的基型构造，再依据不同型号的特性按模块组合方式设计整个系列仪器,7、改善易用性，讲究外形美观,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,如何设计一个光谱仪器,一、明确要设计仪器的类型和用途是单色仪还是光谱仪，用在什么地方，需不需要激发光源等，调查争论，确定原始设计数据工作波段，区分率，色散率等，确定总体方案选用何种光学系统，色散系统，机械构造和电子系统。,二、拟定原理方案，进展初步设计计算包括仪器各主要部件参数计算，系统方正，误差计算，精度分析。,三、仪器各部件的具体构造和电路设计出各种设计的详图，编写技术文档，说明书等,四、部件加工，部件调试，整体联调，进展必要的修改光学，电子，机械构造，数据处理等,|,Creative ways to construct winning e-mails,|,Creative ways to construct winning e-mails,例子,设计一个便携式的可见光波段光谱仪,1、工作波长：400-700nm,2、区分率：0.5nm,3、光栅型光谱仪,4、根本构造：光纤准直光栅会聚线阵CCD,光学系统设计,依据接收系统和光纤确定系统各局部的数值孔径和通光孔径,光栅的选取,光栅装置构造确实定,依据光纤的参数设计准直透镜,依据CCD的参数设计会聚透镜,考虑小型化,