An antenna-coupled detector's directional properties can be verified by measuring its angular radiation pattern. At infrared frequencies, this pattern can be measured by rotating the device while illuminating it with a laser beam. An accurate radiation pattern can be measured only if the device is coaligned with the axis of rotation and the focus of the laser beam. In the alignment procedure presented, the device is rotated to various angles and the distance along the orthogonal axis from the current device position to the laser beam is measured by maximizing its response. Calculations based on these distances provide the new location of the device, which will coalign it with the axis of rotation and the focus of the laser beam. The successful alignment enables accurate radiation pattern measurements.