Type of photoelectric switch and induction mode

The inductive model straight beam device consists of a receiver located within the line of sight of the transmitter.

In this mode, when the beam is blocked from the transmitter to the receiver, an object is detected.

The retro reflector places the transmitter and receiver in the same position and uses the reflector to reflect the reverse beam of the transmitter back to the receiver. When the beam is interrupted and cannot reach the receiver, the object is sensed. Proximity sensing (diffusion) arrangements are devices where the emitted radiation must be reflected away from the object in order to reach the receiver. In this mode, an object is detected when the receiver sees the source of the transmission instead of not seeing it. For example, in a reflection sensor, the diffuse reflection sensor transmitter and receiver are located in the same housing. But the target acts as a reflector, allowing the detection of light reflections far away from the interfering object. The transmitter emits a beam of light (usually pulsed infrared, visible in red light or laser light) to diffuse in all directions, filling the detection area. Then, the target enters the area and deflects part of the beam back to the receiver. When there is enough light on the receiver, it will detect and turn the output on or off.

The stand-alone photoelectric sensor is composed of two parts: optics and electronics. It only needs a power supply. The sensor performs its own modulation, demodulation, amplification and output switching. Some independent sensors provide options such as built-in control timers or counters. Due to technological advancements, self-contained photoelectric sensors have become smaller and smaller.

The remote photoelectric sensor used for remote sensing only contains the optical elements of the sensor. The power input, amplifier, and output switching circuits are located elsewhere, usually in the control panel. This makes the sensor itself very small. In addition, sensor controllers are easier to use because they can be larger. When space is limited or the environment is too harsh, even for remote sensors, optical fibers can be used. Optical fiber is a passive mechanical sensing element. They can be used with remote or standalone sensors. They have no circuits and no moving parts, so they can shine light into harsh environments.