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Physics
Classical Physics
Optics
Lensmaker's equation when the 2 mediums on both sides of the lens are different
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[QUOTE="Charles Link, post: 6457613, member: 583509"] I verified the expression for ## f_2 ##. To do this from first principles, (which I did), you have parallel rays incident from the left, and compute the refraction at the first surface for a height ## h ## using Snell's law with paraxial approximations. Next compute the refraction at the second surface, and finally compute the focal length, where the parallel rays converge on axis, independent of ## h##. It would be a similar calculation for ## f_1 ##. I think the textbook is correct. Note: To compute the angle ## \phi ## of the normal of the curved surface as a function of ## h ##, you can use ## \frac{d \phi}{dh} \approx \frac{1}{R} ##, so that ## \phi=\frac{h}{R} ## in the paraxial ray aprroximation. (Traveling on a circle, ## \frac{d \phi}{ds}=\frac{1}{R} ##, where ## s ## is the arc length. Near the optic axis, ## h \approx s ##). [/QUOTE]
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Forums
Physics
Classical Physics
Optics
Lensmaker's equation when the 2 mediums on both sides of the lens are different
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