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Polarized Light
Polarized Light
When light passes through a polarizing lens, all components of the light wave are blocked except for the components of the light wave in the plane of vibration allowed to pass by the polarizing filter.
Polarized Light
In “plane” or linear polarization, only the components of the light vector parallel to the privileged axis of the polarizer pass through. Light may also be subject to “circular” and “elliptical” polarization methods, which involve adding devices to the light path which alter its characteristics.
Polarized Light
If another polarizing filter is placed in the path of the polarized light beam, and rotated 90° (perpendicular) to the polarizing axis of the first filter, all light will be blocked.
Polarized Light
If the second polarizing filter is rotated to an angle less than or greater than 90° relative to the first polarizing lens, only the components of the light wave vibrating in that plane will pass through the filter.
Principles of Photoelasticity
Instruments designed to observe objects under polarized light are called polariscopes or strain viewers. The first, or fixed, polarizing filter is known as the “polarizer.” The second, or rotating, polarizing filter is known as the “analyzer.” If the analyzer has a calibrated scale that can be used for making quantitative measurements, it is called a polarimeter.
Principles of Photoelasticity
By rotating the second polarizing filter (analyzer), the user can control the amount (intensity) of light allowed to pass through. The components of the two light waves that do pass through at any given angle of analyzer rotation interfere with each other, resulting in a characteristic color spectrum.