Transmittanssina

Transmittanssina, Finnish for transmittance, is the fraction of incident light that passes through a material or optical path. It is defined as T = I_out / I_in, where I_out is the transmitted light intensity and I_in the incident light intensity. Transmittance is a dimensionless quantity that can be expressed as a decimal between 0 and 1 or as a percentage. In spectroscopy and optics, transmittance may be a function of wavelength, denoted T(λ), reflecting how a sample's optical properties vary with color. The complementary quantity is absorbance A, related by A = -log10(T) or A = εcl under Beer-Lambert law for absorbing solutions, where ε is the molar extinction coefficient, c is concentration, and l is path length. Transmittance can be measured with a spectrophotometer, usually using a reference measurement to define 100% transmission; in practice, scattering and reflection losses may require integrating-sphere measurements to obtain total or diffuse transmittance.

Transmittance is influenced by absorption within the material, scattering of light, and reflections at interfaces. Material thickness, wavelength, and microstructure determine the observed transmittance. In engineering and research, transmittance is used to design optical filters, glazing, coatings, and membranes, and to characterize biological tissues, textiles, and photovoltaic components.

In Finnish scientific literature, transmittanssina is used in the same sense as transmittance, often in discussions of optical properties, measurement methods, and applications.