The control of glass stress is a very important link in the glass production process, and the method of applying appropriate heat treatment to control stress has been well known to glass technicians. However, how to accurately measure the glass stress is still one of the difficult problems that confuse the majority of glass manufacturers and technicians, and the traditional empirical estimation has become more and more unsuitable for the quality requirements of glass products in today’s society. This article introduces the commonly used stress measurement methods in detail, hoping to be helpful and enlightening to glass factories:
1. Theoretical basis of stress detection:
1.1 Polarized light
It is well known that light is an electromagnetic wave that vibrates in a direction perpendicular to the direction of advance, vibrating on all vibrating surfaces perpendicular to the direction of advance. If the polarization filter that only allows a certain vibration direction to pass through the light path is introduced, polarized light can be obtained, referred to as polarized light, and the optical equipment made according to the optical characteristics is polarizer (Polariscope Strain Viewer ).YYPL03 Polariscope Strain Viewer
1.2 Birefringence
Glass is isotropic and has the same refractive index in all directions. If there is stress in the glass, the isotropic properties are destroyed, causing the refractive index to change, and the refractive index of the two principal stress directions is no longer the same, that is, leading to birefringence.
1.3 Optical path difference
When polarized light passes through a stressed glass of thickness t, the light vector splits into two components that vibrate in the x and y stress directions, respectively. If vx and vy are the velocities of the two vector components respectively, then the time required to pass through the glass is t/vx and t/vy respectively, and the two components are no longer synchronized, then there is an optical path difference δ
Post time: Aug-31-2023