SICKPhotoelectric SwitchHow to Select：Diffuse/Retro-reflective/Thru-beamThree Sensing Modes Compared
Published：2026-08-18 · Brand：SICK西克 · Category：选型指南
Optoelectronic switches are commonly used in industrial automation production lines to detect, limit and count materials. Sick photoelectric switches are divided into three categories according to the detection principle: diffuse reflection, specular reflection, and counterreflection. The first step in the selection is to confirm the principle of adapting to the working conditions. Mistaking the selection will cause the detection to fail or be wrongly triggered.
The diffuse reflective sensor is integrated with the reflective plate, which is simple to install and suitable for short-distance (generally < 1 m) short-distance limit and in-place detection. The specular reflective type requires a reflective plate, which has a longer detection distance and better resistance to background interference. It is suitable for medium-distance accurate detection. The reflective type is separated from the transmitting end and the receiving end, which has a longer detection distance and better stability. It is suitable for long-distance isolation detection or transparent object recognition.
In addition to the principle, it is also necessary to match the detection distance, object material and color: transparent film, dark rubber have different requirements for photoelectric sensitivity; workshop dust, (and above) models. The following table is a selection comparison of three types of principles.
Selection Comparison Table
| Sensing Type | Operating Distance | Typical Application | Notes |
|---|---|---|---|
| Diffuse | < 1 m | Close range limit, in place detection | Susceptible to background color interference |
| Mirror Coat | 1–5 m | Precise mid-range detection | Align reflector |
| Anti-shooting | 5–30 m+ | Long range, transparent objects | Both ends need to be installed and aligned |
Note: Specifications are based on manufacturer public data and may vary by batch. Please verify with current OEM documentation.
FAQ
Q：Which type of sick photoelectric switch detects transparent objects?
A：Transparent objects preferably use a photoelectric switch for radiation, or a diffuse reflection model with background suppression, which can avoid the leakage detection caused by light transmission.
Q：What should I pay attention to in the selection of dust and moist workshop?
A：And ensure that the lens/window is cleaned regularly to avoid detection failure due to dust vapor occlusion.
Q：How to troubleshoot photoelectric switch error triggering?
A：First check whether the installation is offset and whether the lens is contaminated, and then check the surrounding strong electromagnetic interference and power supply stability. Most false triggers are caused by external working conditions rather than device quality.
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