Glossary Updates12 new terms added to the glossaries · October 2, 2026, 22:44 CEST
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Glossary · Protective devices and interlocks

Safety light curtain

Also known as: light curtain

German: Sicherheitslichtvorhang

In machine safety, a safety light curtain is an opto-electronic protective device that creates a sensing field and initiates a stop when the field is interrupted. It is a type of active opto-electronic protective device (AOPD).

  • Machine safety
  • EU

In one sentence

A safety light curtain stops a machine when its field is interrupted; resolution, response time and mounting distance decide whether it protects.

Example

A press brake has a safety light curtain across the front, mounted at the calculated minimum distance so that the ram stops before a hand can reach the tooling.

How it applies

  • Machine safety: The resolution determines whether fingers, hands or bodies are detected, and together with the overall stopping time it determines the minimum distance.
  • Design: A light curtain does not stop ejected parts and does not detect a person who has passed through it and remains inside. Add guards, presence detection or a manual reset outside the zone where needed.
  • Evidence: Verify on the machine the detection capability with the test rod, the response time and the stopping time, and record the results.
  • Technical documentation: Describe the daily test, the meaning of indicator lamps and the effects of muting or blanking where configured. State that the curtain must not be moved.

Safety light curtain vs. light barrier

A standard light barrier used for process control is not safety-rated. Only a device designed and certified as ESPE may be used to protect people.

By knowledge.aitechdoc.world · Published September 25, 2026 · Last reviewed

Source: IEC 61496 series, Safety of machinery — Electro-sensitive protective equipment

Definitions follow the cited standards and specifications. Where a source is a copyrighted publication, such as an ISO, IEC or EN standard, the definition is a close paraphrase, not a verbatim quotation, so as not to infringe copyright. We recommend reading the original publication. The sections “How it applies” are editorial commentary by AI TechDoc Blog and are not part of any standard.

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