Scatterometer

A scatterometer or diffusionmeter is a scientific instrument to measure the return of a beam of light or radar waves scattered by diffusion in a medium such as air.

They are often mounted on weather satellites to find wind speed and direction, and are used in industries to analyze the roughness of surfaces.

Sigma-0 (σ⁰) is computed from the signal power measurement using the distributed target radar equation.

This is a non-linear inversion procedure based on an accurate knowledge of the GMF (in an empirical or semi-empirical form) that relates the scatterometer backscatter and the vector wind.

[2] Scatterometer backscatter data are applied to the study of vegetation, soil moisture, polar ice, tracking Antarctic icebergs[3] and global change.

[8] The Cyclone Global Navigation Satellite System (CYGNSS), launched in 2016, is a constellation of eight small satellites utilizing a bistatic approach by analyzing the reflection from the Earth's surface of Global Positioning System (GPS) signals, rather than using an onboard radar transmitter.

Scatterometers helped to prove the hypothesis, dating from mid-19th century, of the anisotropic (direction dependent) long distance dispersion by wind to explain the strong floristic affinities between landmasses.

Scatterometers are widely used in metrology for roughness of polished and lapped surfaces in semiconductor and precision machining industries.

[9] They provide a fast and non-contact alternative to traditional stylus methods for topography assessment.

[10][11] Scatterometers are compatible with vacuum environments, are not sensitive to vibration, and can be readily integrated with surface processing and other metrology tools.