Home Career Color imaging illustrates birefringence, polarization, retardation — ScienceDaily

Color imaging illustrates birefringence, polarization, retardation — ScienceDaily


Polarization of light is at the heart of various recent technological innovations, including 3D cinemas and LCD displays. In LCD displays, tiny, electronically controlled liquid crystal elements are placed between polarizers. If, instead, other polarization-changing transparencies, such as cellophane gift wrap and packing tape, are placed between the set of polarizers, an array of filtered polarizations of color can be observed.

In the village American Journal of PhysicsAIP Publishing, Aaron Slypkov of Trent University in Canada investigates the physics of how such colors arise, how they can be controlled, and why subtle changes in viewing angle, sample orientation, and the order of film layers between polarizers can have a dramatic effect on observed colors.

The study highlights visual examples of concepts related to birefringence, such as addition, subtraction, and order of operations. For example, the non-commutative nature of birefringent addition is usually illustrated using formal matrix mathematics. However, in this case, the researchers use color visualization.

“I use the visual language of colors to illustrate subtle physics that are often only demonstrated mathematically,” said Slypkov.

It was inspired in part by the work of artist Austin Wood Komarow, who made a career out of applying polarizing filter painting techniques to fine art. Austen coined the term “polarization” or collage polarization to describe her art.

Austin created a wide range of works using complex layering of cut cellophane and other birefringent polymer films interspersed with layers of film polarizers. Her works range from small individual works that fit on a shelf to massive career installations in institutions such as the Disney Epcot Center in 1981 and the Gyeongsangnamdo Institute of Science Education in Jinju, South Korea in 2017.

“In this work, I clarify the relationship between polarization filtering and observed colors. I demonstrate how various aspects of birefringence in common household films create opportunities and create challenges for their use in art,” Slypkov said.

To create color with a polarizing filter, all that is needed is a birefringent sample sandwiched between the polarizers that form the polarization gate. Many household items can create a kaleidoscopic array of colors and patterns.

Clear plastic cutlery, for example, provides a classic demonstration where localized stress in the polymer structure results in differential birefringence that can be observed through a polarizing shutter. Likewise, haphazardly folded kitchen wrap, gift basket wrap, and multiple layers of duct tape can create intricate patterns that resemble stained glass.

“Manipulating birefringent films to create color images is fun and intellectually stimulating. Many physical nuances of polarization, birefringence, delay and color theory can be observed in this accessible but expansive work,” said Slypkov.

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Materials is provided American Institute of Physics. Note: Content can be edited for style and length.

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