Path length/Optical Path length Problem 1. Light of 520 nm travels in a material
ID: 1413193 • Letter: P
Question
Path length/Optical Path length Problem 1. Light of 520 nm travels in a material having index of 1.46. a. If the light makes 24 oscillations while in the layer, how thick is the layer? b. How long (in seconds) does it take the light to traverse the layer? c. How far would the light travel in this much time in a vaccuum? d. How many of the 520 nm waves fit in this distance? e. Multiply the layer thickness from “a” by n and compare to the distance in “c”. f. Write a sentence that will help you review the meaning of “Optical Path Length” for the final exam using this example.Explanation / Answer
lambda=520nm
n1=1.46
oscillations=24
a) Thickness=lambda*24/n1=8.548µm
b) v=d/t...t=d/v=n1*thickness/c=4.16x10^-14 seconds
c) In vacuum, n=1. Therefore d=v*t=c*4.16x10^-14=12.48µm (distance traveled in vacuum)
d) d/lambda=12.48µm/520nm=24 oscillations
e) 8.548µm*1.46=12.48µm is the same as d
f) The wavelength is different depending on where it is propagating and it reduces its value by the effect of the refraction index.