Aperture Transmission Calculator

Gaussian beam clipping · T = 1 − exp(−2·a² / w²)

P_out = P_in · (1 − e^(−2a²/w²))

Inputs

P_in Beam initial power

Geometry — any two, the third is computed

a Aperture size

w Beam size at aperture (1/e²)

T Transmission fraction

Presets

Beam & aperture

Centered circular Gaussian beam, 1/e² convention. T = 1 − exp(−2a²/w²).

Results

Transmitted power

—

P_in · T

Transmission

—

1 − e^(−2a²/w²)

Clipped / blocked power

—

P_in − P_out

a / w ratio

—

aperture vs beam

Peak intensity I₀

—

2·P_in / (π·w²)

Avg intensity at aperture

—

P_out / (π·a²)

Aperture for 99.9%

—

a = w·√(−½·ln(1−0.999))

Aperture diameter

—

T = 1 − exp(−2·a²/w²) · P_out = P_in · T · a = w · √(−½ · ln(1 − T)) · w = a · √(−2 / ln(1 − T))
Centered circular Gaussian (TEM₀₀), beam size at 1/e² intensity. Rule of thumb: a ≥ 2w transmits >99.9%. Ref: Saleh & Teich, Fundamentals of Photonics, 2nd ed.