Polariscope for glass and plastic products

The Strain viewer ( Ref.PSV-202) has been designed to observe and analyze the internal stress of preform and other plastic products .

Detecting object
1. Preform ( Color and colorless types )
2. Other transparent plastic products
Plastic molds , plastic bottle , cosmetic bottle , beverage bottle, plastic tray, plastic film ., etc

Measuring Principle
The internal stress plastic products has a birefringent characteristic. In other words, if there is stress inside of these types of products, light from he polarized lamp will be divided into different units, which produce optical interference phenomenon(ripple patterns) in turn.
Under white-light lamp, you can see aubergine ripples, which is caused by the presence of stress.
From the observation of colored patterns, you can see stress distribution directly, then evaluate and improve the annealing process.
The inspection of plastic molds is more complex as the colored patterns cased by stress is irregular. A similar situation may occur with glass products, which is called stress stretching. For example, a qualified mold will have a large amount of stress released by tension.

The role of full-wave plate :
The full-wave plate increases or decreases the full wavelength of a phase difference, thereby forming a colored pattern, which is easier to analyze.