OPTICAL LEVEL GAUGE APPARATUS AND METHOD, LIQUID TANK ASSEMBLY AND VEHICLE EMPLOYING THE SAME

In order to improve liquid level gauging inside liquid tanks (22), especially cryogenic liquid tanks, the invention provides an apparatus and method for determining the liquid level, L. A light source emits outgoing light rays (34) that are back reflected or scattered by the tank wall (24) of the liquid tank (22). The back reflected or scattered incoming light rays (48) are received by a light conducting device (36), which conducts the incoming light rays (48) towards a sensor device (54). The sensor device (54) has optical sensors (56) that are coupled to the light conducting device (36) in such a manner that there is a one-two-one relationship between each optical sensor (56) and a specific tank wall portion (58). Due to the change in the amount of light that is received by the optical sensor (56) after the outgoing light rays (34) were refracted by the liquid surface (46), the liquid level determining device (60) is capable of determining the liquid level L.