A polariscope is an essential tool for detecting strains in transparent materials. It can be used by Quality Control to monitor production items, or to inspect incoming materials. The Model 243 is also very useful in production or laboratory for checking glass welds, bends, castings, or degree of annealing. Instant detection of strains can be found in transparent materials. The tint plate adds color to the image for determination of strains.
The unit features a 6" diameter viewing area with a rotatable polarizer and a full wave retarder tint plate. The light source is provided by two 15 watt bulbs, 120V AC or DC is required.
The photo shows the strains in a clear plastic tape dispenser. The Polariscope shows the true strain patterns in transparent materials.
When a photo elastic material is subjected to a load and illuminated with polarized light from the measurement instrumentation (called a reflection polariscope), patterns of color appear which are directly proportional to the stresses and strains within the material. The sequence of colors observed as stress increases is: black (zero stress), yellow, red, blue-green, yellow, red, blue-green, yellow, red, etc. The transition lines seen between the red and green bands are known as "fringes." The stresses in the material increase proportionally as the number of fringes increases. Closely spaced fringes means a steeper stress gradient, and uniform color represents a uniformly stressed area. Hence, the overall stress distribution can easily be studied by observing the numerical order and spacing of the fringes.