Figure 1a shows a slotted optical switch. An LED is mounted in a plastic housing, facing a phototransistor, but separated by a gap. If something moves into the gap, it blocks the light path between ...

Würth Elektronik has revealed two reflective optical sensors. These are simple devices, with an infra-red emitter and a photo-transistor, both facing upwards, but work at an unusual wavelength. “These ...