Pin Placement System with Ultrasonic Collimator

Collimator 1 comprising a body with an aperture extending completely through the body in a transmission direction T, the aperture having a width W being the maximum diameter of the aperture along its extent, and a length L in the transmission direction, wherein the ratio of the width to the length is greater than or equal to 1. The collimator is operative to limit the lateral extent of ultrasonic waves orthogonal to the transmission direction. The aperture may have a width to length ratio in the range 2.5 to 3.5. The aperture width may be 3 mm to 4.5 mm and the length may be 0.7 mm to 1.5 mm and it may be of circular cross-section. An ultrasonic sensor may comprise an emitter of ultrasonic waves and the collimator 1 and may detect objects in a target zone separated from the emitter by a dead zone. The collimator may be mounted on the emitter, so it is in the dead zone. The ultrasonic sensor may be part of a pin placement system for placing tooling pins within a printing machine.