Norland Connect-Chek CC6000, Руководство пользователя

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9.2 INTERFEROMETRY BASICS
Light wave interference occurs when two or more waves of the same frequency or
wavelength combine to form a single wave whose amplitude is the sum of the amplitudes
of the combined waves. Constructive and Destructive interference is the most striking
examples of light wave interference. Constructive interference occurs when the light
waves are completely in phase with each other (the peak of one wave coincides with the
peak of the other wave). Destructive interference occurs when the light waves are
completely out of phase with each other (the peak of one wave coincides with the trough
of the other wave). Refer to figure below for an illustration of Constructive and
Destructive interference.
Interferometers can produce images and data to sub micron accuracy using the
principle of wave interference. Interferometers use a single coherent light source. In
order to produce two separate light waves for interference to occur, a partially reflective
beam splitter is used. As the light hits the beam splitter, one wave front is transmitted
through the beam splitter, though an objective lens, and to the object being examined.
The other light wave reflects off of the beam splitter onto a stationary reference mirror.
After both light waves are reflected off of the surfaces (the surface of the object being
examined and the reference mirror), the waves combine to produce constructive and
destructive interference waves, also known as light and dark fringes respectively. Each
dark fringe identifies a specific height on the surface of the object being examined.
Typically, two adjacent dark fringes have a height difference of 1/2 a wavelength of the
INTERFEROMETRY BASICS