Bilingual edition: English is preserved and Chinese follows each unit. Terminology uses the confirmed v20260916 glossary; automated semantic review remains traceable.
中英双语版：英文原文完整保留，中文紧随对应单元；术语采用 v20260916 确认表，自动语义审校结果可追溯。

Sodium Doublet on Fabry-Perot

钠双线在法布里-珀罗干涉仪中

The image at left below shows the appearance of the interference fringes of the sodium doublet produced by Fabry-Perot optics. This is the appearance at one position. As the micrometer is adjusted to increase the mirror spacing, the appearance changes as the fringes merge together. If the micrometer is advanced until the fringes look the same again, then you have advanced one of the fringe sets one full order with respect to the other. This allows you to calculate the wavelength difference. The video at right shows the progression which is used to determine the wavelength difference.

左边的图像显示了由法布里-珀罗光学产生的钠双线的干涉条纹外观。这是在某一位置的外观。当微分尺被调节以增加镜面间距时，外观会变化，因为条纹会相互融合。如果微分尺继续调节直到条纹看起来相同 again，那么你已经将一个条纹集相对于另一个条纹集移动了一个完整的波长差。这允许你计算波长差。右边的视频展示了用于确定波长差的进程。
Fabry-Perot geometry
法布里-珀罗几何
Fabry-Perot resolution
法布里-珀罗分辨力
Index

Interference concepts

Example of sodium doublet
索引干涉概念 示例：钠双线
 
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Doublet Separation, Fabry-Perot

双折射分离，法布里-珀罗

The resolvance of the Fabry-Perot interferometer is sufficient to resolve closely spaced spectral doublets like the sodium doublet and the hydrogen-deuterium doublet.

法布里-珀罗干涉仪的分辨能力足以分辨 closely spaced 的谱双峰，如钠双峰和氢-氘双峰。

The experimental procedure yields a distance of movement of the interferometer mirror which allows the doublet separation to be calculated from the relationship

实验程序得到干涉仪镜片的移动距离，这使得可以通过以下关系计算双合分隔
Show
显示
The average wavelength of the doublet must be known from other measurements to make use of this relationship.
For average wavelength = λ = = nm
对于平均波长 = λ = = 纳米
中文译文中的待填/计算数值依次对应：1：wa 2：w。实际数值以上方原输入框为准。
and interferometer carriage movement = mm
干涉仪移动量 = 毫米
中文译文中的待填/计算数值依次对应：1：d。实际数值以上方原输入框为准。
the doublet separation is
双重分裂是
 = = nm
= = 纳米
中文译文中的待填/计算数值依次对应：1：sra 2：sr。实际数值以上方原输入框为准。
Fabry-Perot resolution
法布里-珀罗分辨力
双重线的平均波长必须通过其他测量来确定，才能利用这一关系。
 Index

Interference concepts
索引干涉概念
 
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Doublet Separation Expression

双重线分离表达式

Subraction of the two distances obtained in the doublet experiment gives the following expression:

This expresses the fact that the shorter wavelength has gained an order on the longer wavelength. Combining terms gives

这表达了短波长比长波长多了一个数量级的事实。合并项得

Substituting this back into the top equation gives

将此代入上一公式可得

The relationship for the doublet separation is then

双重态分离的关系式为
Calculation
计算
Fabry-Perot interferometer
法布里-珀罗干涉仪
Calculation
计算
双缝实验中得到的两个距离相减得到以下表达式：
 Index

Interference concepts
索引干涉概念
 
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Doublet Separation, Experiment

双分子分离实验

The experimental procedure involves examining the interference fringes of the light at normal incidence ( angle = 0°) such that constructive interference is produced by one wavelength of the doublet

实验过程涉及在正常入射（角度=0°）条件下考察光的干涉条纹，使得通过双线的一条波长产生 constructive interference。

while the other wavelength is adjusted to a half-integer condition. This can be seen in the interference pattern as a weaker ring half-way between the stronger interference maxima. This corresponds to

而另一个波长被调整为半整数条件。这可以在干涉图样中看到，表现为在较强干涉极大值之间较弱的环。这对应于

Advancing the micrometer until this condition occurs again provides data from which the doublet separation can be calculated.

将微米尺推进直到该条件再次出现，可以获取用于计算双峰间距的数据。
Show doublet
expression
展示双重表达式
Fabry-Perot interferometer
法布里-珀罗干涉仪
Index

Interference concepts
索引干涉概念
 
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