Optical Approach to Augment Current Float Sensing Method of Determining Cryogen Fluid Height Within a Tank

Innovative Imaging and Research, a small technology development company, has teamed with the University of Southern Mississippi Instrument and Cryogenics Research Laboratory to integrate existing NASA Stennis Space Center heritage cryogen level monitoring technology with noncontact optical methods and advanced signal processing to create a 21st century liquid cryogen level measurement technique. We propose to place a fiber-optic laser range finder on the upper surface of a low pressure cryogen run tank and use the existing Hall effect float system as an optical target to reflect the light signal back to the range finder. We also propose combining measurements obtained with the fiber-optic range finder with those taken by the heritage system using a custom Kalman filter signal processing algorithm to reduce measurement noise and increase overall accuracy. Our optical technique has several advantages over the existing Hall effect method. It yields near continuous measurements and is not dependent on the location of individual sensors. It is based on an alternate physics approach and therefore yields completely independent results. The optical range finder instrument calibration is performed outside the tank, so test operation is not significantly impacted and run tanks do not need to be emptied. In addition, an optical fiber mounted on the upper surface of a cryogen tank does not present foreign object debris (FOD) concerns. During our Phase 1 STTR project we will demonstrate our concept in a university cryogen research laboratory using a commercial optical range finder. In Phase 2 we plan to demonstrate our concept with fiber-optic technology using the SSC Instrument Test Apparatus under a NASA Space Act Agreement. Our Phase 1 concept is at a technology readiness level (TRL) of 2. We expect to complete Phase 1 at a TRL of 4 and complete Phase 2 at a TRL of 6.