Abstract: To improve liquid level gauging inside liquid tanks, especially cryogenic liquid tanks, an apparatus and method for determining the liquid level are provided. A light source emits outgoing light rays that are back reflected or scattered by the tank wall of the liquid tank. The back reflected or scattered incoming light rays are received by a light conducting device, which conducts the incoming light rays towards a sensor device. The sensor device has optical sensors coupled to the light conducting device such that there is a one-two-one relationship between each optical sensor and a specific tank wall portion. Due to the change in the amount of light that is received by the optical sensor after the outgoing light rays were refracted by the liquid surface, the liquid level determining device is capable of determining the liquid level.

Abstract: In order to improve free space optical communications, an optical communication terminal includes a laser source, a photo detecting apparatus and an optical input/output assembly. These components are controlled by a control logic. In order to have the optical communication terminal to be self-compatible, the optical input/output assembly selectively routes the outgoing beam and incoming beam depending on their respective beam polarization. To this end, the optical input/output assembly may include a polarizing beam splitter together with a quarter-wave plate.

Abstract: Methods, systems, and devices for free-space optical communications. An aircraft includes a flat optical communication terminal on an external surface of the aircraft, the flat optical communication terminal being configured to communicate with a ground station via a free-space optical communication link.

Abstract: Systems for wireless power transfer (WPT) include one or more WPT transmission devices and one or more WPT receiver devices to wirelessly receive power transmitted by the one or more WPT transmission devices. The WPT receiver devices are arranged at a fixed position relative to each of the WPT transmission devices. A WPT transmit controller of the systems is coupled to the one or more WPT transmission devices to control WPT transmission properties of the one or more WPT transmission devices in order to harmonize and adapt the transmit power level at the fixed position of the one or more WPT receiver devices.