Alfatronix manufactures Slot Sensor. The Slot Sensor is used to fixed distance through beam IR sensor with slot of 3, 10, 50 and 120 mm. The minimum object sensed is 2mm typical. [Optionally object as small as 0.1 mm can be sensed].
Alfatronix is the supplier of Analogue Inductive Proximity Switches, Beam IR Sensors, Capacitive Proximity Switches, Cooling Tube, Inductive Proximity Switches, Power Supply Relay Units, Retro Reflective IR Sensors, Slot Sensor, etc.