KEYENCE UK provides Photoelectric Sensors; Detect presence using a LED light source.
Fundamentals of Photoelectric Sensors
Photoelectric Sensors - Banner Engineering - Power Motion
Introduction to Photoelectric Sensors - Technical Articles
Throughbeam photoelectric sensors
Overview of Photoelectric Sensors
What is a Photoelectric Sensor? Sensor Basics: Introductory
Twidec/ 0-2M Adjustable Indoor Wall Mounted
Photoelectric Sensors, Diffuse Sensors
All About Photoelectric Sensors
Built-in amplifier photoelectric sensors - PZ-G series
WL12G-3P2582P01 Small Photoelectric Sensors - SICK Sensor – Inosaki