Physics

Optical Density Calculator

Find optical density (absorbance) from transmittance.

Calculated Output

Optical density 2

Formula: OD = −log₁₀(T)

Step-by-Step Breakdown

1. Values used:

2. Transmittance (0–1) = 0.01

4. Optical density = 2

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The math behind it

OD = −log₁₀(T), where T is the fraction transmitted. Each unit of OD blocks 90% of remaining light.

T = 0.01 (1% passes) → OD 2.

What OD do laser goggles need?

Enough that the transmitted power is eye-safe for the laser's wavelength and power.