The invention relates to a kind of volumetric pipet. Each conductor bar has a respective first end extending beyond the first end of said rotor core. The apparatus includes a mast staging hydraulic circuit which diverts hydraulic fluid from the second mast section actuator to the first mast section actuator using a multi-position valve having an open position and a restricted flow position. The filter assembly is capable of transmitting a portion of an electromagnetic spectrum into the dielectric material to generate a filtered output with a predetermined range of wavelengths that displays minimal angle dependence, when viewed from a range of incidence angles ranging from normal to 90\xb0.