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Optical Path Length

by Joeseye
Tags: length, optical, path
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Mar8-12, 12:11 PM
P: 4

My homework constantly refers to something called the optical path length, L - I'm not exactly sure what this is. It's in the equation below. This question is in relation to astrophysics and dust extinction in the Interstellar Medium.

Relevant equations:

Dust optical depth, τλ = Ng∏a2L


My best guess is that it's something to do with the penetration distance into a cloud(???).

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Mar8-12, 05:12 PM
P: 11,689
Hmm. Optical depth is something different from optical path length. Optical depth should be related to optical extinction (light absorption by a medium). Optical path length is usually the physical distance of the path that light follows through a system, multiplied by the index of refraction of the medium. L*n in other words.

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