Strain Inspection in Glass with Polariscope Strain Viewers

Strain is the deformation an object undergoes when external stress is applied. In several measurement applications, strain is quantified as a unitless measure expressed in percentage. Strain inspection and testing is crucial to measure how a material such as a piece of glass reacts to it to determine its yield strength, tensile strength, brittleness, and more. A piece of colored glass may show strain or deformation under stress due to various factors, such as uneven cooling and tool marks when shaping. This leads to breakage or uneven optical performance across the piece of glass. Polariscope strain viewers are commonly used to study/measure the properties of glass under stress,. This post discusses the significance of strain inspection before making glass articles, and the working and significance of polariscope strain viewers.

Challenges Associated with Detecting Strain in Glass

There are certain difficulties when visually identifying strain in colored glass, especially colored glass with vibrant hues. Here are some of the challenges.

• With bare eyes or even a lens, spotting all the defects and deformities in a glass piece may not be possible.
• It is not possible to measure the stress applied and the exact point at which the glass may break.
• Spectral reflectance or Rλ is the light or energy ratio reflected by the glass surface to the incident light or energy on the surface, which is measured as a function of wavelength or lambda. The spectral reflectance in coated and uncoated glass is different, and hence it is challenging to measure manually. For instance, the daytime spectral reflectance of an uncoated, clear glass is around 8%.
• Hence, a reliable inspection tool such as a polariscope strain viewer is needed to ensure invisible imperfections aren’t present in a glass before it is used in any commercial or industrial application.

Introducing Polariscope Strain Viewers

Colored glass has a wide application across industries including construction, home décor, and Polariscopes are used as strain viewers in the colored glass industry. It is an NDT tool that offers accurate analysis of stress and strain, structural defects introduced during manufacturing, variations in glass transparency, and more. It is an automatic 2D-measuring system which measures birefringence and retardation values in a transparent glass piece or any sample. The retardation values are used to determine the strain in the sample using the rotating analyzer method. Here, polarized light is passed through the glass piece, which helps interpret qualitative and quantitative defects in color distribution, tensile strength, and more. It then passes through another polarizer at a series of angles. Light falls on the CCD to get the data on the glass sample. The data from all angles of the second polarizer is combined and retardation is calculated

Benefits of Using Polariscope Strain Viewers for Glass

There are several benefits of using a polariscope strain viewer for colored glass. Here are some of them.

• This is a nondestructive testing method that helps protect the beauty and integrity of the glass piece and can be done even if the glass piece is being processed.
• It offers a clear optical view from various angles, large viewing areas, measurement area sizes around 205☓205mm, and a wider view of deformities, if any. Hence, this tool facilitates accurate data production.
• It is effective for various glass types, regardless of the color intensity.
• It reveals hidden stress patterns, allowing for corrective actions before assembly or final installation.
• It facilitates consistent color distribution and enhances the overall aesthetics.
• It ensures safety and prevents breakage by determining the tensile strength.

Applications of Polariscope Strain Viewers in Glasswork

Here are some application areas of polariscope strain viewers in the clear and colored glass segment.

• It helps inspect individual colored glass pieces before assembly in stained glass windows or mosaics.
• It is useful in identifying defects and measuring tensile strength of clear glass, which is used across industries such as medical, clinical research, automotive, electronics, and more.
• It identifies the minutest strain caused by cutting, grinding, or polishing techniques.
• It helps ensure the structural integrity for large glass art installations or even the glass used in construction of buildings, windows, and more.
• It helps ensure the highest quality standards for colored glass production.

If you have any questions about using polariscope strain viewers in the glass ijnspection field or need to discuss your requirements or options, feel free to contact the team at Barnett Technical Services. The company is an authorized distributor for various brands of spectroscopy instruments such as polariscope strain viewers and more.

Related Products:

LSM-9002LE: Strain measurement in the visible across a 175×175 mm area

LSM-9002S: Strain measurement in the visible with a variable field of view for 10-10 to 60×60 mm

LSM-9001NIR: Near-IR system to measure strain in semiconductors

LSM-9100WNIR: Near-IR system to measure strain in resins and other plastics