Fiber Numerical Aperture Calculator

NA · Acceptance angle · Core & cladding indices — with live cone visualization

NA = √(n₁² − n₂²)

Inputs

Core refractive index

n₁ (typical 1.44 – 1.50 silica)

Cladding refractive index

n₂ (must be < n₁)

Numerical aperture

NA (0 < NA < 1 typical)

External medium

n₀ (air = 1.000, water ≈ 1.333)

Enter any two values — the third is computed automatically.

Core — Clad — NA —

Numerical aperture

—

NA = √(n₁² − n₂²)

Acceptance half-angle θ

—

θ = arcsin(NA / n₀)

Full acceptance cone 2θ

—

Full angular aperture

Critical angle θc (internal)

—

sin θc = n₂ / n₁

Fiber presets