O
- object speed limit
- object table
- ophthalmic lens
- Ophthalmometer
- Ophthalmoscope
- Ophthalmoscope graticules
- optical axis
- optical centre
- optical centre distance OCD
- optical dimensions
- optical material
- optical radiation
- Optical radiation hazard
- optical zone of magnifier
- Optimization
- Organic hard resin: thermoplastic hard resin
- Organic hard resin: thermosetting hard resin
optical axis
Straight line, perpendicular to both optical surfaces of a spectacle lens, along which light can pass undeviated. NOTE: An aspheric surface has a unique axis of symmetry, the axis of rotation. Unless the centre of curvature of the opposite surface lies on this axis, there ist no true optical axis.