| optical bench | |
| —n | |
| an apparatus fitted for experimentation in optics, typically consisting of a table and an adjustable arrangement of light source, lenses, prisms, etc | |
| a calculus or concretion found in the stomach or intestines of certain animals, esp. ruminants, formerly reputed to be an effective remedy for poison. |
| a screen or mat covered with a dark material for shielding a camera lens from excess light or glare. |