Abstract: A two-way actively stabilized QKD system that utilizes control signals and quantum signals is disclosed. Because the quantum signals do not traverse the same optical path through the system, signal collisions in the phase modulator are avoided. This allows the system to have a higher transmission rate than a two-way system in which the quantum signals traverse the same optical path. Also, the active stabilization process, which is based on maintaining a fixed relationship between an intensity ratio of interfered control signals, is greatly simplified by having the interferometer loops located all in one QKD station.

Abstract: A camera back having a frame for receiving a camera component and a locking arm pivotally connected to the frame. The locking arm includes an engagement surface for holding the camera component securely to the frame. The locking arm comprises a top and bottom locking member pivotally mounted to the frame with a handle connecting the top and bottom locking members. A biasing element urges the engagement surface against the frame in a downward position to securely hold the camera component in the frame. A tension device is attached to the frame so that after the camera component is locked into place on the camera back, the tension device effectively holds the locking arm in one position to avoid inadvertent unlocking.