Polariscope – Test PET bottles and Glass for Minute Flaws

Polariscope – Test PET bottles and Glass for Minute Flaws

What is Polariscope?

It is a testing instrument to measure the defects in the transparent materials, anything that can pass light. Polariscope strain viewer is a device consisting of 2 polarized lenses and a light source. Depending upon its industry of use, its models vary. For instance, a gemmologist does not require a big instrument. A hand-held instrument is suitable for his job. On the other hand, for industrial purpose like testing of glass or plastic, a table top model is the perfect fit.

Why it is needed?


Polariscope is basically an optical testing instrument used to identify the defects in the material due to strain. It is used to ensure the quality of product and to avoid the product failure. When a material, say a gemstone, experience strain it may get deformed or cracked. This hugely affects the quality of the product and thus decrementing the price of gemstone drastically. Similarly, in PET bottle industry or glass industry, it determines any manufacturing defects or defect that occur due to strain. PET bottles and glass are used in packaging and storage. Any compromise with the quality can lead to product failure. This may lead to disastrous results as packaging may contain harmful chemical or flammable liquids. So, it serves the purpose of quality management and quality control.

How to use it?

Polariscope strain viewer is an easy to use device. It works on the principle of changing refractive index of the light. Materials like plastic and glass does not refract the light doubly. But can behave in this manner if subjected to external force causing internal stress.  This can be seen, by placing the sample under the polarized lens. The light which is mounted under one of the lens passes light through the material, which is viewed through the lens placed opposite the light. There is no external display. Test results can only be visually observed and logged manually for records.

Refractive index; The angle with which light is changing its path when entered from one medium to other. For instance, if light is passing through a glass sheet; here refractive index will change at 2 points, 1. When light enters from air to glass 2. When light enters from glass to air.
What are its specifications? 

  • Light used is monochromatic in nature.
  • The light used in this instrument is either battery operated or power source is required externally.
  • The diameter of field of view is 190mm
  • It is easy to tilt it in 180ºC and can be clamped in any position
  • Its working space can be changed from 290mm to 440mm.
  • Polarized stain viewer is highly calibrated as per NABL approved lab.
  • Results are accurate and highly reliable

Another model of polariscope strain viewer is available which is suitable for observing even the tiniest of the defects in the glass. The biggest advantage if this models is that it can be used post production for quality analysis, especially in decorative articles.