The act of collimating or something collimated(noun)
Aligning lenses along line of sight to minimize aberrations(noun)
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Use "collimation" in a sentence
"Exposure to ionizing radiation during a medical examination can be limited by lead shielding, tube collimation and using the lowest dose necessary to obtain a diagnostic image."
"E.g., the formation and collimation of jets is still quite unknown."
"The replacement is a nice model from Astrosystems, which features four-point collimation adjustment."