Internal strain in clear acrylic plastic revealed by the polariscope. A large screw has been tightened with great force into a block of clear acrylic plastic. As a result, the screw is pressing into the plastic, causing the plastic to experience strain around the screw, especially at the tip. This strain causes a local change in the “index of refraction” of the plastic, creating “rainbows” of color as visible light passes through the plastic and gets refracted into its component colors, as happens in a prism.
These “rainbows” are visible only in a “polariscope”, in which the specimen is placed between two “crossed” polarizing filters and illuminated from behind by a fluorescent light bulb in a “light table”.
The term “crossed” means that the polarizing filters are oriented with their polarization axes perpendicular to each other.
The term “polarization” describes the direction of the electric and magnetic components of the light, which oscillate in a transverse fashion as light travels. “Polarization” refers to the direction of these oscillations.
JON MULL Photo
- Filename
- a09_polariscopy screw stress_w.JPG
- Copyright
- Amy Chou
- Image Size
- 550x380 / 206.9KB
- Contained in galleries
- 20100524 Crowley Microscrope Various
