Difference between Optical and Geometrical length?

In summary, the difference between optical and geometrical length is that optical path length takes into account the index of refraction, while geometrical length does not. Optical path length is commonly used to calculate phase shifts in interferometers.
  • #1
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Difference between Optical and Geometrical length!?

I'm having this question since 2 times now in the theoretical part of the exam & still I couldn't find anything about it in the book neither in google.
Can anyone who's more experienced in Optical Physics give me the answer to this please !?
 
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  • #2
Optical path length depends upon the index of refraction encountered; it is the same as geometrical length when the index of refraction is everywhere equal to 1.

See http://en.wikipedia.org/wiki/Optical_path_length

Optical path length is often used as the difference between two optical paths: then the difference in optical path length - this is used to calculate the phase shift between coherent light sources traveling the two paths, as in an interferometer.
 

1. What is the difference between optical length and geometrical length?

Optical length refers to the actual distance traveled by light in a medium, while geometrical length refers to the straight-line distance between two points.

2. How are optical and geometrical lengths related?

In most cases, the optical length is longer than the geometrical length due to the refraction of light in a medium.

3. Can you provide an example of how optical and geometrical lengths differ?

One example is when light travels through a prism. The geometrical length is the straight-line distance between the entry and exit points of the prism, while the optical length is longer due to the refraction of light within the prism.

4. Are there any situations where the optical length and geometrical length are the same?

Yes, in a vacuum, the optical and geometrical lengths are the same as light does not experience any refraction.

5. How does the difference between optical and geometrical lengths affect scientific experiments?

The difference between optical and geometrical lengths is important to consider in experiments that involve light, such as measuring the speed of light or studying the behavior of light in different mediums. It is also essential in fields such as optics and astronomy where precise measurements of light are necessary.

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