What is the optical difference between BK 7 and fused silica?

BK7 glass is one of the most common and widely used borosilicate crown glasses available. It performs well against most chemical tests, it is relatively hard, and does not scratch easily. BK7 glass can be handled without the need for special precautions.

The bubble and inclusion content is also very low. BK7 has excellent transmission from 350nm to 1.5 m. It can be a low-cost alternative to fused silica. Fused silica is another common material used for optics.

It has greater transmission than BK7 in the UV and IR spectrum. Transmission ranges from 180nm to 2 m. Fused silica has a low coefficient of thermal expansion, providing stability and resistance to thermal shock over large temperature deviations.

Fused silica has increased hardness and resistance to scratching. It can be an excellent alternative to BK7 glass, depending on the application. More.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.