Tests of a Motion Pickup of the Infra-Red Type

摘要

A pickup suitable for the measurement of ocean water level variations is described. Tests were conducted in the laboratory of a development model of the motion pickup using an infra-red source (light bulb) as the motion sensor. Specifically, an infra-red sensitive photocell is positioned so as to receive energy from a source only when a hole in the rim of a wheel is in the plane of the source and the center of the wheel. Then, as the wheel is caused to rotate, the cell receives a pulse of energy, through the hole from the moving source and thereby activates a time measuring circuit. The wheel continues to rotate until the hole is next positioned so that the cell receives a pulse of energy from a fixed source. This causes the time measuring circuit to stop and from calibration data the position of the moving source relative to a given horizontal plane is calculated and recorded (plotted). Successive positions of the moving source are calculated and recorded to provide a continuous record as a function of time of the displacement of the moving source.