What is a scatterometer used for?
Scatterometers are active remote sensing instruments for deriving wind direction and speed from the roughness of the sea. They are used by low Earth orbiting satellites and act like radars: they transmit electromagnetic pulses and detect the backscattered signals.
How is BSDF measured?
When measuring the BSDF of specular surfaces, it is very important that the sample be planar over the illuminated area. If the surface is not planar, then the surface will reflect the incident laser light into a solid angle that the detector will interpret as an angular spread in the BSDF.
How scatterometry works?
In a nutshell, scatterometers transmit pulses of microwaves with relatively short wavelengths (relatively high frequencies) and measure the backscatter from the wind-roughened ocean. The faster the winds are, the rougher the ocean surface, and the more radiation that backscatters to the scatterometer.
What is scatterometry metrology?
Scatterometry is a metrology technique that combines the sensitivity of diffraction from periodic structures with a first principle solution of electromagnetic wave diffraction from these structures.
What is an active remote sensor?
Remote sensing instruments are of two primary types: Active sensors, provide their own source of energy to illuminate the objects they observe. An active sensor emits radiation in the direction of the target to be investigated. Reflected sunlight is the most common source of radiation measured by passive sensors.
How has satellite technology helped the study of oceanography?
What are two ways satellite technology aids oceanographers and astronomers in studying the oceans and outer space? Satellite technology allows oceanographers and astronomers to collect data remotely and communicate across the globe and in real time.
What does BSDF mean?
The bidirectional scattering distribution function (BSDF) radiometrically characterizes the scatter of optical radiation from a surface as a function of the angular positions of the incident and scattered beams.
How do you measure scatter?
Research concepts: Quantifying scatter
- Calculate the mean (i.e. the average value).
- For each data point, calculate the difference between itself and the mean.
- Square each of these differences.
- Add up the squared differences.
Which NASA sensor measures wind over the ocean?
SeaWinds scatterometer
The SeaWinds scatterometer is a specialized microwave instrument that measures near-surface wind speed and direction all the time, even when it is cloudy. Although designed for measurements over the ocean, SeaWinds can also collect data over land and ice.
What is Scatterometry in semiconductor?
Definitions. Scatterometry is a technique for measuring periodic structures on a surface with dimensions from a few nanometers to tens of micrometers. Scatterometry is a fast, nondestructive technique and is, therefore, suitable for in-line metrology.
Which camera is an example of a passive sensor?
The infrared viewer, for example, is specially made to “see” objects emitting infrared radiation (even in the dark). In general terms, sensors that use external energy sources to “observe” an object (e.g., the sun light to observe the Earth) are called “passive sensors”.
