WordNet
n. an instrument designed to aid vision
Wikipedia
An optical instrument either processes light waves to enhance an image for viewing, or analyzes light waves (or photons) to determine one of a number of characteristic properties.
Usage examples of "optical instrument".
With the aid of this it will be possible to organize together round a common spatial centre that part of the activity of levity which escapes the optical instrument and thus remains cosmic, and that part which appears by itself in terrestrial space.
Life had obligingly revealed to one in its whole extent the romance of this little girl, had lent one, for the study of lier, first one optical instrument, then another, and had added to one's carnal desire an accompaniment which multiplied it an hundred-fold and diversified it with those other desires, more spiritual and less easily.
What we produce must be as finely finished as the most beautiful piece of jewelry you have ever seen - or perhaps a precision optical instrument.
He fixed his eyes to an optical instrument, across which were two hair lines.
He turned to another officer, one stooping to look through a tripod-mounted optical instrument.
This level of magnification shows the eye as an optical instrument.
When the lid is opened, you can fold out an optical instrument vaguely suggestive of a sextant, and you can set the controls and read the meters.