4.1 Measurement???The refractive index at any wavelength of a piece of homogeneous glass is a function, primarily, of its composition, and secondarily, of its state of annealing. The index of a glass can be altered over a range of up to 1??10-48201;(that is, 1 in the fourth decimal place) by the changing of an annealing schedule. This is a critical consideration for optical glasses, that is, glasses intended for use in high performance optical instruments where the required value of an index can be as exact as 1??10-6. Compensation for minor variations of composition are made by controlled rates of annealing for such optical glasses; therefore, the ability to measure index to six decimal places can be a necessity; however, for most commercial and experimental glasses, standard annealing schedules appropriate to each are used to limit internal stress and less rigorous methods of test for refractive index are usually adequate. The refractive indices of glass ophthalmic lens pressings are held to 5??10-4 because the tools used for generating the figures of ophthalmic lenses are made to produce curvatures that are related to specific indices of refraction of the lens materials.
4.2 Dispersion???Dispersion-values aid optical designers in their selection of glasses (Note 1). Each relative partial dispersion-number is calculated for a particular set of three wavelengths, and several such numbers, representing different parts of the spectrum might be used when designing more complex optical systems. For most glasses, dispersion increases with increasing refractive index. For the purposes of this standard, it is sufficient to describe only two reciprocal relative partial dispersions that are commonly used for characterizing glasses. The longest established practice has been to cite the Abbe-number (or Abbe ??-value), calculated by:
where vD is defined in 3.2 and nD, nF, and nC are the indices of refraction at the emission lines defined in 3.2.
4.2.1 Some modern usage specifies the use of the mercury e-line, and the cadmium C???and F??? lines. These three lines are obtained with a single spectral lamp. 材料属性选择适合应用的光学窗口时,材料属性至关重要,其中包括透光率、折射指数和硬度。这些特性对于确定最适合您需求的理想窗口类型起着决定性作用。下图展示了提供的各种窗口材料及其相应的透射波段。为您的应用选择适当窗口的其他几个关键属性包括折射率、阿贝数、密度和热膨胀系数。下面的选择指南列出了我们可用的窗口基板的光学、机械和热性能及其尺寸和厚度范围。... 我们的IRFS32光纤使用InF3(氟化铟)玻璃生产,并在310
nm - 5.5 µm范围内具有高透过率,而单模工作范围从3.2
µm到5.5
µm。右图展示了它们和标准石英玻璃光纤相比的波长相关衰减率。氟化物玻璃的折射率接近于石英折射率。因此,氟化物玻璃光纤在光纤-玻璃和光纤-石英界面上都具有低回波损耗和菲涅尔反射。折射率、数值孔径(NA)和衰减曲线请在曲线标签中查看。... (5) 若待测试样折射率不在1.3~1.7范围内,则阿贝折射仪不能测定,也看不到明暗分界线。3.阿贝折射仪的校正和保养阿贝折射仪的刻度盘的标尺零点有时会发生移动,须加以校正。校正的方法一般是用已知折射率的标准液体,常用纯水。通过仪器测定纯水的折光率,读取数值,如同该条件下纯水的标准折光率不符,调整刻度盘上的数值,直至相符为止。... 法国数学家柯西发现折射率和光波长的关系,可以用一个级数表示: 其中a,b,c是三个柯西色散系数,因不同的物质而不同。只须测定三个不同的波长下的折射率n(λ),代入柯西色散公式中可得到三个联立方程式,解这组联立方程式就可以得到这物质的三个柯西色散系数。有了三个柯西色散系数,就可以计算出其他波长下的折射率不需要再测量。 除了柯西色散公式之外,还有其他的色散公式。...
where ve is defined in 3.2 and ne, 了解光学窗口
单模光纤介绍
阿贝折射仪原理、使用方法与维护保养
光学经典理论|光学色散详解
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