Let bring an another similar glass. Make standing two polarization filters after lamp and adjust it to most black turn angle. Then keep the glass between both filters - shall see the even most smallest thermal stress contours in the volume. Very sensitive method.

 

Let bring an another similar glass. Make standing two polarization filters after lamp and adjust it to most black turn angle. Then keep the glass between both filters - shall see the even most smallest thermal stress contours in the volume. Very sensitive method.

Interesting idea. Unfortunately, I have 4 or 5 similar types of glasses and do not know if I even have one of the same type.

 

A co-worker was doing some quick upgrades to her home while planning to sell it. One of the upgrades was a bathroom vanity with a moulded glass counter top/sink. A few days after installing the vanity they were shocked awake in the middle of the night by a loud bang that she described as a sounding like a gun shot. They found that the glass top of the vanity had exploded and there was glass embedded in the walls and ceiling. If someone was in the room when it happened they could have been very seriously injured.