Abstract: An adiabatic liquid volume sensor system is described, which employs a main chamber in a back-to-back configuration with a reference chamber of known volume. The system measures liquid volume in the main chamber by making low frequency acoustic measurements of the acoustic pressure differences in the two closed chambers when driven with a sinusoidal frequency from the same speaker. Pressure transducers in each chamber measure acoustic adiabatic pressures in each chamber. The ratio of these pressures multiplied by the known volume of the reference chamber yields the volume of gas in the main chamber. The volume of liquid is equal to the known volume of the main chamber minus the calculated gas volume.

Abstract: A device (10) for changing the focus and field of view of an optical device having an optical element (19, 21) which is movable grossly to change field of view and movable incrementally to change focus of the device (10) with either field of view includes an operator actuatable control system for varying incrementally the axial position of this optical element within each of the regions to focus the optical device in each field of view mode. The device (10) includes a control knob (31), a threaded shaft (33) coupled to the control knob (31), a pair of stop members (37, 39) engaging threadedly the threaded shaft, and a linkage (45, 53, 49, 63, 59, 55, 67, 69) for converting axial motion of a stop member along the threaded shaft to incremental movement of the movable optical element along the primary optical axis (29).