What is an ellipsometer?
ellipsoometry is an optical technique for measuring thickness and optical properties of extremely thin films or material layers. Measurable properties are refractive index or how much light is bent and the level of light absorption, called absorption coefficient . The ellipsometer is a device used to perform these measurements.
Ellipsometers works so that September a well -defined light source on the material and captures the reflection. Modern ellipsomets use lasers, usually helium-on lasers. The ellipsoter beam goes through the polarizer for the first time, allowing only a light -oriented light -oriented light. It then passes through a device called a compensator that elliptically polarizes the light beam. The remaining light is then reflected from the studied material.
The analysis depends on the Snell law; When the beam of light hits the material, some of them are immediately reflected and some pass to a remote side material before the reflection. By measuring the difference between the two reflections, the thickness can be determinedof it. The reflected light is also subject to a change in polarization; This change is used to calculate the refractive index and the absorption coefficient.
In order to function properly, the material examined must meet certain physical properties. The sample must be composed of a small number of well -defined layers. The layers must be optically homogeneous, have the same molecular structure in all directions and reflect a significant amount of light. If some of these requirements are violated, standard procedures will not work.
ellipsomets are very sensitive devices that are able to measure layers as thin as one atom. They are widely used in the production of semiconductors, where the material layers of the material are chemically grown at the top of each.
ellipsometry is non -destructive; The material measured by the ellipsometer is not adversely affected by the process. Due to this function, the use of ellipsometers in biological science is increasingch. Biological materials are much less uniform than produced materials and generally do not have physical properties necessary for traditional ellipsoometry. New techniques have been developed for working with such materials, such as the use of multiple ellipsometers arranged at different angles.