Constant Focal Length Acoustic Lens.
Patent, Filed 3 Dec 81, patented 13 Nov 90,
DEPARTMENT OF THE NAVY WASHINGTON DC
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This patent discloses temperature compensation system that adjusts the temperature of an acoustic lens fluid in a prescribed manner to maintain the index of refraction of the fluid constant relative to the surrounding water thereby maintaining the focal length of the lens constant over its operating temperature range. The system comprises two temperature sensors, a programmed lens fluid temperature prescriber and an error amplifier all cooperating to direct a servomechanism system to adjust a temperature control system to either heat or cool the lens fluid to the prescribed temperature so that its index or refraction and focal length are held constant. edc