Focal length equation from Radii of Curvature and refractive index of lens

AI Thread Summary
The discussion focuses on finding an equation for the focal length of a biconvex lens based on its radii of curvature, thickness, and refractive indices. The original poster seeks a reliable reference for this equation, as well as a more general version that includes the refractive index of the surrounding medium. They mention a Wikipedia link but express the need for additional credible sources. Ultimately, the poster finds the information they were looking for through further research and suggests that optics textbooks, such as Hecht, contain the relevant equations. The conversation highlights the importance of reliable references in optics calculations.
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Hi all,

I'm looking for an equation which will give me the focal length of a biconvex lens given that we know both Radii of curvature, the thickness of the lens and the refractive index inside and outside.

An equation is given on wikipedia here http://en.wikipedia.org/wiki/Focal_length as

d5d9b5b95cf3fd9ea7f2549ae4ee8fa6.png


I need something I can reference though and I can't see this equation anywhere else I look. Also I need a more general version of the equation which involves the refractive index of the substance surrounding the lens.
Could anyone point me to a derivation of this formula or lead me in the right direction?

I also need to find a legitimate source for the back focal distance shown on the same page of wikipedia:

30eebfeda11493b69809a64439377125.png


Thanks all!

EDIT: Found what I was looking for, just needed a bit more snooping!
http://physics.tamuk.edu/~suson/html/4323/thick.html
 
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Any decent optics textbook (e.g. Hecht) should have that equation, in a chapter on thick lenses.
 

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