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Thin Film Optical Path Difference Calculator

OPD = 2nt·cos θ — conditions for constructive/destructive interference.

Calculates optical path difference OPD = 2·n·t·cos θ for a thin film of thickness t and refractive index n. Determines constructive (OPD = mλ) or destructive (OPD = (m+½)λ) interference.

Nadia Almasri By Nadia Almasri
Published Last reviewed 1 min read

Inputs

m
°
m

Results

Enter values and click Calculate to see results.
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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

OPD = 2·n·t·cos θ

In depth

Calculates optical path difference OPD = 2·n·t·cos θ for a thin film of thickness t and refractive index n. Determines constructive (OPD = mλ) or destructive (OPD = (m+½)λ) interference.