Features :

 1.Stress testing

 2.Multi-focal lens testing

 3.Lens scratches check.

Technique Parameters :

 1) Electric Voltage: 220V/50Hz  or  110V/60Hz  
 2) Power: 120W
 3) Weight: 2.5kg
 4) Volume: 350x280x200mm 

About Stress testing
Normally, we can observe the following four situation through stress test machine
* Stress equalizing  - Lens edge around present homogeneous line
* Stress over  -     Lens edge around present sharply strip line
* Local stress over  -     Lens edge local around present sharply strip line
* Stress less  -     Lens edge around almost without any line

Stress over analysis
* The lens grinded over
* Lens shape does not match with the shape of lens frame, include the edge
* The lens curvature does not match with the lens frame

Stress less analysis
* Lens too small