Photoelectric sensors serve as essential detection tools in industrial automation, performing object presence verification and distance measurement tasks. These non-contact sensors offer long-range detection capabilities while delivering fast, precise results.

There are mainly four types of photoelectric sensors：

1.Through-beam sensors

2.Retroreflective sensors

3.Diffuse reflective sensors

These sensors operate using two fundamental detection methods:

1.Through-beam

2.Reflection

Beam detection

Engineers install the emitter and receiver in separate housings, precisely aligning them across the target object’s path. The system detects objects when they completely interrupt the light beam between components. This configuration delivers maximum detection range, strongest signal output, and optimal light/dark contrast.

Characteristics	Limitation
Maximum optical range Optimal contrast between light and dark The surface reflectivity and color have little influence Optimal jump point repeatability	Two components are wired through the detection area Demands precise alignment

Reflection detection

The sensor combines emitter and receiver in one housing, positioned on the same side as the target. A reflector bounces the light beam back to the detector. Objects trigger detection when interrupting this reflected beam. This popular solution offers powerful sensing without requiring wiring across the detection area.

Characteristics	Limitation
Remote Highlight/dark contrast Easy to install and align	Highly reflective surfaces may cause false triggers

Diffuse reflection detection

The integrated sensor housing contains both emitter and receiver components. When targets enter the detection zone, their surfaces reflect emitted light back to the detector. Engineers can control the detection area by adjusting light source angles, spacing, power levels, and beam patterns.The light source and detector components are installed in a single sensor housing, located on the same side of the object to be measured and aligned with the cross-field of view. When the target moves to this area, the light emitted by the light source is reflected back to the detector through the target surface for detection.

Characteristics	Limitation
Installation and alignment are simple. Just wire on one side of the sensing area It can detect the differences in surface reflectivity	Restricts sensing range Depends on target surface reflectivity for contrast and range