Transmissionsgrad

Transmissionsgrad (literally "transmission degree") is a measure of the fraction of incident energy that passes through a system, material, or device. It is commonly used in optics, electronics, and acoustics to describe how much of an input signal or radiant power is transmitted rather than absorbed, reflected, or scattered. In general terms it is defined as the transmitted power divided by the incident power, and is typically expressed as a number between 0 and 1 (often shown as a percentage). In optics it is called transmittance and may depend on wavelength, angle of incidence, and polarization. Spectral transmittance is denoted T(λ) and describes the transmission at each wavelength; the total transmittance over a spectrum is the integral of transmitted power across the spectrum divided by the input power.

Factors that influence the transmittance include absorption and scattering within the material, Fresnel reflections at interfaces, surface roughness, thickness, and the wavelength of the signal. For a homogeneous slab, transmittance typically decreases with increasing thickness and absorption coefficient and varies with wavelength according to the material’s optical properties.

Measurement is performed with calibrated detectors or integrating spheres to compare transmitted and incident power, often reporting results as a percentage. Standards and instrumentation depend on the application, such as optical components, glazing, or solar-energy devices.

Transmissionsgrad is the German-language counterpart to the English term transmittance; in English-language literature it is usually referred to as transmittance or optical transmittance. See also transmittance, absorption coefficient, attenuation, and optical density.