New Model Series StrainMatic® M4

Quality is Measurable

Imaging polarimeter systems for the automatic and objective measurement of stress birefringence in glass and plastics
The breaking resistance and processability of glass and plastic products are heavily determined by the contained residual stress which depends on the stages of forming and annealing. Through the effect of stress birefringence the residual stress also has an influence on the polarization of light. Therefore, constant testing of residual stress is a very important part of quality control.
With the development of the StrainMatic® product series, ilis gmbh based in Erlangen, Germany, has been successful in identifying stress in a medium on time.

"Even minimum mechanical stress in material can affect the polarization of light, which is an undesirable effect especially when there is an optical demand which has to meet the highest precision" explains Henning Katte, Managing Director of ilis. The new StrainMatic® M4 has been specially developed for the optical industry. In comparison with StrainMatic® M2 and M3, the M4 type offers a higher measuring accuracy and parallel light paths over the whole measuring area.

The first StainMatic® M4/300 with a measuring field size of 240 x 180 mm2 has made possible the fast and exact examination of stress in large sized optical raw glass at SCHOTT AG, Advanced Optics in Mainz, Germany. The equipment works according to the photoelastic principle: Linear polarized light is non-destructively conducted through the object and the alteration of the polarization angle is measured automatically. A large telecentric lens captures the internal stress distribution from the center to the border uniformly.

The instrument realizes a lateral resolution of less than 1 mm, enabling a fast and two-dimensional measurement of the stress birefringence in large specimens. The result is displayed graphically color-coded which enables a quick overview of the residual stress distribution and makes a detailed analysis possible. At SCHOTT, the method is primarily applied for materials and components used in industrial optics, especially related to astronomy, microlithography and laser optics.

Another model of the M4 series, the StrainMatic® M4/50 Inline with 40 x 30 mm2 measuring field size is available in the market since December 2007. Ist modular and robust design allows its easy integration into existing production and testing lines.
A typical application is a continuous process control in production of tube glass and pharmaceutical packages. Besides the Inline variant a laboratory version with a closed housing is also available.