To address the NASA need for innovative methods to measure liquid propellant tank volume and tank fluid level with improved accuracy, repeatability, and minimal tank entries for maintenance and calibration, Luminit, LLC, proposes to develop a new non-contact Luminit Optical Tank-level Sensing system (LOTS), based on the optical measurement of a small spotlight shone on the surface of the liquid. This approach incorporates commercial off-the-shelf components and Luminit opto-mechanical design, which enables us to meet NASA requirements for a novel liquid level sensor for low-density fluids such as liquid hydrogen, and offers the possibility of remote operation, compact size. In Phase I, Luminit will demonstrate the feasibility of accurate measurement of a low-density fluid by building and testing a proof-of-concept prototype, which will reduce development risk in Phase II. In Phase II, Luminit plans to build a functional prototype for cryogenic liquid level measurements. The demonstrated results will offer NASA a replacement for the multiple float switches currently in use. LOTS is expected to be at TRL 2 by the end of Phase I, with the results of this project paving the way to reach TRL 6 by the end of Phase II.