What Is Optical Density?
Optical density is a complex characteristic of materials that can slow the speed of light propagation and produce refraction (refraction) effects.
Optical density
- Comparison of optical density of aluminum-plated film and thickness of aluminum layer
- Optical density (OD) is defined as the characterization of a material's light-shielding ability. It is measured with a transmission lens. Optical density has no dimensional unit and is a logarithmic value. Generally, only optical density measurements are performed on aluminized films and pearlescent films.
- Optical density is the logarithm of the ratio of incident light to transmitted light or the reciprocal of the transmittance of light. The calculation formula is
- OD = log10 (incident light / transmitted light) or OD = log10 (1 / light transmittance)
- Generally, the optical density value of the aluminum coating is 1-3 (that is, the light transmittance is 10% -0.1%). The larger the value, the thicker the aluminum coating. The ANSI / NAPM IT2.19 of the National Bureau of Standards does the test conditions. Detailed regulations.
- Comparison table of OD value, square resistance value and aluminum layer thickness
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