throughbeam

Throughbeam is a term used in photoelectric sensing to describe a configuration in which a transmitter and receiver are placed on opposite sides of a sensing path. The transmitter emits a collimated beam of infrared or visible light toward the receiver. In normal operation, the receiver detects the beam and outputs a defined signal. When an object or obstruction passes through or breaks the beam, the receiver detects the interruption and changes its output, enabling control systems to stop a machine, count items, or trigger an alarm.

Compared with diffuse or retroreflective sensors, through-beam sensors typically offer longer sensing ranges and are less affected by the color or reflectivity of the target, since detection is based on beam interruption rather than surface reflection. The main advantages include high reliability, fast response, and the ability to detect at greater distances. The main drawbacks are the need for precise alignment, an unobstructed line of sight, and susceptibility to environmental factors such as dust, dirt on lenses, vibration, fog, or bright sunlight.

Common uses include machine guarding in manufacturing, automation lines for object presence detection, packaging and material handling, and access control on doors or gates. Variants include high-power models for industrial environments and fiber optic through-beam systems for installations where space or alignment is challenging. Throughbeam arrangements are often integrated into broader safety and automation architectures leveraging appropriate interlocks and monitoring provisions.