Lowering a camera to a position just above the sea floor is a critical operation. The "pinger" method of camera-to-bottom positioning has proved to be an excellent technique. A sonar transducer on the camera sends one sound signal directly to the surface, and another to the bottom. The bottom signal, reflected from the sea floor, rises to the surface where its delayed arrival time is measured against the camera signal beamed to the surface. An Alden recorder is used to record each direct or reflected signal as received.
The nature of infrared radiation and its transmission through the atmos pheric constituents up to the entrance window of an optical system are described. The current state-of-the-art of infrared technology, both civilian and military, is outlined, and some future improvements and developments are predicted on a basis of extrapolations of present equipment and com-ponent capabilities.
The previous papers have explained the processes involved in getting the infrared radiation from the target of interest, through the intervening atmosphere, and directed to the desired place by the optics. This paper discusses the techniques and procedures utilized to pick up the target information at that point and process it into a form which provides the required action or information.