[mass noun] A very pure kind of glass used for lenses.
- ‘Optical fibers are made of extremely pure optical glass.’
- ‘Etched in optical glass, the reticle has the clarity Leupold scopes are renown for.’
- ‘Schott, a Carl Zeiss subsidiary, produces optical glass that is widely regarded as the finest in the world.’
- ‘Platinum crucibles are used to melt high-quality optical glass and to grow crystals for computer chips and lasers.’
- ‘A powerful internal light will illuminate the perforated 12-metre section near the stop, which will taper off to a tip of optical glass.’