Optical Density Calculator
Find optical density (absorbance) from transmittance.
Optical density measures how much a filter or sample blocks light.
The math behind it
OD = −log₁₀(T), where T is the fraction transmitted. Each unit of OD blocks 90% of remaining light.
Worked example
T = 0.01 (1% passes) → OD 2.
FAQ
What OD do laser goggles need?
Enough that the transmitted power is eye-safe for the laser's wavelength and power.