Infrared photo gate for triggering a digital interface or a digital counter (U8533341). For time measurements in experiments on free fall, motion on a track or pendulum oscillations and for counting pulses. It can be operated in internal mode using the built-in infra-red light source or in external mode with the aid of a laser pointer, which needs to be obtained separately. It then acts as a wide-range light barrier, allowing it to be used at sporting events, for example. The gate includes an operational indicator light, stand rod with screw thread, M6 bolt for attachment to a roller track (U35001) and connector lead with 8 pin miniDIN plugs for the digital counter.