A Polariscope is an essential optical device used to analyze and detect internal stress in transparent materials, such as glass and plastic. It works by passing polarized light through a sample, highlighting areas of stress that are invisible to the naked eye. Widely used in industries like manufacturing, engineering, and packaging, a polariscope helps identify weak points, ensuring material integrity and preventing failures during production. This non-destructive testing method is critical for ensuring the quality and reliability of products, making it a valuable tool in quality control processes.