\[OPL=nd\]
Variables
OPLoptical path length (m)
nrefractive index
dphysical distance traveled by light (m)
Description
What is this formula?
The optical path length formula calculates the effective distance traveled by light inside a medium. It accounts for the refractive index of the material and represents how optical media slow down light propagation.
When to use it
Use this formula when analyzing wave propagation, interference, phase differences, lenses, optical fibers, interferometers, and multilayer optical systems.
Example
A light beam travels through a glass slab.
Data:
n = 1.50
d = 0.020 m
Formula:
OPL = n*d
Substitution:
OPL = 1.50*0.020
Result:
OPL = 0.030 m
The optical path length inside the glass is 0.030 m.
Applications
Interferometry, lens systems, optical coatings, fiber optics, wave optics, holography, microscopy, and photonics engineering.