different between alidade vs diopter

English

Alternative forms

• alhidade, alhidad, alidad (all obsolete)

Etymology

From French alidade, from Spanish alidada, from Arabic ??????????? (al-?i??da), perhaps from ?????? (?a?ud, “upper arm”).

Pronunciation

• IPA^(key): /?æ.l?.de?d/

Noun

alidade (plural alidades)

1. (cartography, astronomy, surveying) A sighting device used for measuring angles.

Synonyms

• turning board, diopter (obsolete)

Translations

Further reading

• alidade on Wikipedia.Wikipedia

Italian

Noun

alidade f

1. plural of alidada

Portuguese

Alternative forms

• alidada

Noun

alidade f (plural alidades)

1. (cartography, astronomy, surveying) alidade (sighting device used for measuring angles)

English

Alternative forms

• dioptra
• dioptre
• dioptry (obsolete)

Etymology

From Latin dioptra, from Ancient Greek ??????? (dióptra).(Can this⁽⁺⁾ etymology be sourced?)

Noun

diopter (plural diopters)

1. A unit of measure of the power of a lens or mirror, equal to the reciprocal of its focal length in meters. Myopia is diagnosed and measured in diopters.
2. The dioptre adjustment mechanism of a pair of binoculars or of a camera viewfinder.
3. (photography, dated) A lens element attached to the front of a photographic lens to shorten the lens's minimum focus distance; also called a "close-up filter".
4. (obsolete) Any lens system, such as a telescope.
5. (obsolete) A theodolite or similar surveyor’s angle measuring device.
6. (obsolete) An alidade.
7. (obsolete) A surgical speculum.
8. (obsolete) An instrument for drawing the skull by projections.

Translations

References

Anagrams

• dioptre, peridot, periodt, proetid, proteid, protide, pterido-, pteroid, reptoid