Some small loss from CR39 and Crown glass
does not cause too many problems.
More expensive models use barium crown glass
Its scanning window is crown glass
prism and there is special anti-scratching coating on the scanning surface.
is harder than flint glass, with a lower index of refraction and lower dispersion.
53--is closer to that of crown glass
than other thermoplastics; thus, their use in place of glass requires minimal design changes.
Extreme made its mark by producing some of the most respected target scopes in the business, employing German-engineered crown glass
with world-famous Zeiss multilayer, non-reflective coatings for scratch resistance, crystal-clear target image and superior low-light performance.
Pilkington plc originated in 1826 as the St Helens Crown Glass
Company founded with the technical knowledge of John William Bell and finance from three of the most influential local families - the Bromilows, the Greenalls and the Pilkingtons.