Absolute liquid level sensor with refractive encoding

An apparatus for measuring liquid level, comprising in combination,

• a. a vertical ruler passing substantially vertically through one or more liquid interfaces;
• b. supporting means for said ruler;
• c. a measurement scale with encoded distance information along the length of said ruler comprised of a sequence of area elements whereby each said area element divides an incident first beam of radiative energy into two or more second beams of radiative energy, where,
• i. each of said second beams has a propagation direction substantially different from the propagation direction of any other said second beam and substantially different from the propagation direction of said incident first beam;
• and
• ii. said area elements divide said first beam into a pattern of said second beams selectively in accordance with a code indicative of distance along said ruler;
• d. one or more floats that encompass and substantially freely traverse said ruler, wherein each float contains:
• i. one or more sources of radiative energy for producing and directing said first beams of radiation onto said area elements;
• ii. one or more radiative energy detectors to indicate second beams of radiation whereby distance information encoded along said ruler is read;
• and
• iii. sending means for transmitting said distance information to a data interface unit external to said floats, which is capable of one or more of the following data functions:
• 1. display
• 2. storage
• 3. retransmission.
• e. means for converting said distance information to liquid interface level.