Production Tour
![](fileadmin/user_upload/Factory-Tour_1.jpg)
Weighing and assembly of raw material.
![](fileadmin/user_upload/Factory-Tour_2.jpg)
Mixing in the V shaped blender.
![](fileadmin/user_upload/Factory-Tour_3.jpg)
Mixed raw material called "batch" is put into a platinum lined pot and melted into amorphous glass.
![](fileadmin/user_upload/Factory-Tour_4.jpg)
Glass is stirred to insure good homogeneity.
![](fileadmin/user_upload/Factory-Tour_5.jpg)
The pot is removed from the oven after several hours.
![](fileadmin/user_upload/Factory-Tour_6.jpg)
The pre-melt is poured into a pan.
![](fileadmin/user_upload/Factory-Tour_7.jpg)
After casting, the glass is cooled and crushed. Then the refractive indices are measured for process control.The crushed glass is called "Cullet".
![](fileadmin/user_upload/Factory-Tour_8.jpg)
The cullet material shown above is melted again to achieve consistent optical values and properties.
![](fileadmin/user_upload/Factory-Tour_9.jpg)
The cullet is melted in a large tank and formed into strip glass. The strip glass is slowly cooled using a continuous annealing Lehr to remove stress. The strip glass exits the annealing tunnel quite slowly.
![](fileadmin/user_upload/Factory-Tour_10.jpg)
Measurement: Important properties such as refractive indices and internal transmittance are measured via a sampling method.
![](fileadmin/user_upload/Unbenannt-10a.jpg)
Inspection of glass: After cutting the Strip glass, samples are inspected for bubbles, striae and inclusions via bright light and striaescope.
![](fileadmin/user_upload/Factory-Tour_12.jpg)
Another quality control is the investigation for stress birefringence. Tensions in the glass are localizable by the optical birefringence which they cause.
![](fileadmin/user_upload/Factory-Tour_13.jpg)
Annealing process
![](fileadmin/user_upload/Factory-Tour_14.jpg)
The final product is an optically high-purity and striae free glass bar.