[ aw-toh-kol-uh-mey-ter ]
/ ˌɔ toʊˈkɒl əˌmeɪ tər /
an instrument combining the functions of a telescope and collimator, for detecting and measuring very small deviations in a beam of light.
Origin of autocollimator
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019