LVI. Investigations in optics, with special reference to the spectroscope
LVI. Investigations in optics, with special reference to the spectroscope
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DOI：
10.1080/14786447908639715
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发表时间：
1879-12
期刊：
影响因子：
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通讯作者：
Lord Rayleigh F.R.S.
中科院分区：
文献类型：
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作者：
Lord Rayleigh F.R.S.
478瑞利勋爵的光学研究。近似于一个平面，这将回答的目的，符合家庭的表面最有可能beproduced;在第二种情况下，家庭的椭圆或双曲曲面能够（与适当的重点）给予良好的定义只包含一个对称成员-完美的平面。为了通过实验检验理论结果的正确性，必须保持与真实表面相适应的焦点，并且不允许重新调整，因为通过重新调整，其误差可能在或多或少的程度上得到补偿。还有一个困难，前面的考虑没有涉及到，仍然有待提及。在检验平面的普通方法中，通过测量通过望远镜观察远点时所需的焦点变化，首先是直接的，然后是在表面反射后，发现当反射更倾斜时，检验更精细。直接根据波动理论的原理计算镜子的焦距，可以最好地理解对明显不一致的解释。设ACB（图8）为（抛物面）镜的弧，其反射平行光线GA、tt D、KB（图8）。聚焦到F。AD= y，DF= f，CD= t。在计算各种光线的延迟时，我们将把与在D处反射的HD一致的光线在F处的相位作为标准（如由平面镜ADB反射），而不是在
478 Lord Rayleigh's Inve~ tlgatioT~ s in Optics. approximating to a plane, which will answer the purpose, coincides with the family of surfaces most likely to beproduced; in the second case the family of ellipsoidal or hyperbolic surfaces capable (with suitable focus) of giving good definition contains only one symmetrical member--the perfect plane. In order to test experimentally the correctness of the theoretical result, it would be necessary to retain the focus suitable to the true surface, and not to allow a readjustment by which its errors may be in greater or less degree compensated. A further difficulty~ not touched by the preceding considerations, still remains to be mentioned. In the ordinary method of testing plane surfaces by measuring the change of focus required when a distant point is viewed through a telescope, first directly, and then after reflection in the surfacej the test is found to be more delicate as the reflection is more oblique. The explanation of the apparent inconsistency will be best understood by a calculation of the focal length of mirrors, founded directly upon the principles of the wave theory. Let ACB (fig. 8) be an arc of a (parabolic) mirror, which reflects parallel rays GA, tt D, KB Fig. 8. to a focus F. AD= y, DF= f, CD= t. In calculating the retardations of the various rays~ we will take as standard the phase at F of a ray coincident with HD~ reflected at D (as by a plane mirror ADB) instead of at