Advanced Fresnel Reflection Calculator

Analyze polarized reflections across refractive boundaries with confidence. Inspect angle-sensitive transmission and optical turning points. Export clean results, graphs, and comparison-ready values for reporting.

Calculator Inputs

Plotly Graph

The graph shows s-polarized, p-polarized, and unpolarized average reflectance versus incident angle for the current refractive indices.

Example Data Table

Medium 1 n₁ Medium 2 n₂ Incident Angle Transmitted Angle Rs Rp Average Reflectance
Air 1.0000 Glass 1.5000 45.0000° 28.1255° 9.2013% 0.8466% 5.0240%
Glass 1.5000 Air 1.0000 50.0000° Total internal reflection 100.0000% 100.0000% 100.0000%

Formula Used

Snell’s law: n₁ sin(θᵢ) = n₂ sin(θₜ)

s-polarized amplitude reflection: rₛ = (n₁ cos θᵢ − n₂ cos θₜ) / (n₁ cos θᵢ + n₂ cos θₜ)

p-polarized amplitude reflection: rₚ = (n₂ cos θᵢ − n₁ cos θₜ) / (n₂ cos θᵢ + n₁ cos θₜ)

s-polarized amplitude transmission: tₛ = 2n₁ cos θᵢ / (n₁ cos θᵢ + n₂ cos θₜ)

p-polarized amplitude transmission: tₚ = 2n₁ cos θᵢ / (n₂ cos θᵢ + n₁ cos θₜ)

Power reflectance: Rₛ = |rₛ|² and Rₚ = |rₚ|²

Power transmittance: T = (n₂ cos θₜ / n₁ cos θᵢ) × |t|²

Unpolarized average reflectance: R̄ = (Rₛ + Rₚ) / 2

Brewster angle: θ_B = arctan(n₂ / n₁)

Critical angle: θ_c = arcsin(n₂ / n₁), only when n₁ > n₂

When sin(θₜ) > 1, the interface enters total internal reflection. In that case, real transmitted power becomes zero and reflectance becomes one.

How to Use This Calculator

  1. Enter a label for the incident medium and transmission medium.
  2. Provide the refractive index of the first medium, n₁.
  3. Provide the refractive index of the second medium, n₂.
  4. Enter the incident angle in degrees.
  5. Click the calculate button to generate the full Fresnel solution.
  6. Review the result block shown above the form.
  7. Inspect s and p reflectance, transmittance, Brewster angle, and critical angle.
  8. Use the CSV or PDF buttons to export the result summary.
  9. Check the graph to compare angular behavior across the full angle range.

FAQs

1. What does this calculator measure?

It computes Fresnel reflection and transmission at a flat boundary between two media. It reports s and p polarization behavior, transmitted angle, Brewster angle, critical angle, and average unpolarized reflectance.

2. What are s and p polarizations?

s polarization has its electric field perpendicular to the plane of incidence. p polarization has its electric field parallel to that plane. Their reflection behavior generally differs strongly with angle.

3. Why is p-polarized reflectance sometimes zero?

At Brewster angle, the p-polarized reflected amplitude becomes zero for ideal non-magnetic media. That means p-polarized light is fully transmitted in power terms at that exact angle.

4. When does total internal reflection occur?

It occurs when light travels from a higher-index medium to a lower-index medium and the incident angle exceeds the critical angle. The transmitted wave becomes evanescent and reflected power reaches one hundred percent.

5. Does this tool support absorbing materials?

No. This version assumes real refractive indices and lossless isotropic media. For metals or absorbing layers, the refractive index becomes complex and the equations require a more advanced model.

6. Why do reflectance and transmittance sum near one?

For lossless interfaces, energy conservation applies. The reflected and transmitted power fractions add to one, aside from tiny rounding differences caused by decimal formatting in the displayed results.

7. What does phase inversion mean here?

A negative amplitude reflection coefficient indicates a phase reversal of 180 degrees in that polarization component. This matters in interference, thin films, and polarization-sensitive optical analysis.

8. What is the unpolarized average reflectance?

It is the arithmetic mean of s and p reflectance. This approximation is commonly used when incident light has no preferred polarization direction at the interface.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.