The history of the light curtain

The history of the light curtain

Safety light barriers, safety light screens, or light curtains are an alternative to traditional machinery guards and barriers. They provide safety for anyone in the vicinity of the machine or area of danger. Unlike barriers and guards, a light curtain can switch off machinery within a fraction of a second if an intrusion is detected. They are classed as optoelectronic devices. So, we know what they are but what is the history of the light curtain? Let’s look.


In 1951, the German inventor, Erwin Sick (1909-1988) patented two of his inventions. Photoelectric sensors and autocollimation. These inventions allowed light to be transmitted and received. Either by a transmitter to receiver, or by transmitter to mirror back to transmitter. This can then measure distance, the presence of items, or the lack of them. Sick’s inventions were the basis of the light curtain, but the development of hardware and software has enhanced its use and versatility.


The advancement of technology has made the light curtain a much more versatile product. You can get one with anything from 0 to 20 metre span. Which means you can now protect small areas or large areas, or entire warehouses. The beams can be from 14mm to 70mm wide. So, the sensors can detect small things like fingers or the entire body, depending on your needs. If something passes through the beams a signal is sent to shutdown the machinery. This happens within a fraction of a second. They can automatically reset once the presence is no longer detected, or they can be reset manually from out of the danger area. You can also get light curtains with a feature that will allow materials to pass through the beam without shutting down. This may slow down the shutdown response though, and machines that complete their cycle before beginning their shutting down process are still a danger to operators. However, in these cases, you can curtain off an area, or an entire room, this can give the machine the time it needs to complete its shutdown process before anyone is close enough to be harmed.


The future of light curtain technology is going to be exciting and add to the product’s versatility. Unfortunately, light curtains are still being under-exploited in many industries and by many companies. So, to understand how light curtains can help your business and which ones suit your needs, you need expert advice. We recommend a reputable company, and our choice would be RS.

From the early days of optoelectronic devices to the light curtains of today has been a 70 year process that has saved many lives and limbs throughout manufacturing, processing, and the automotive industries. They will continue to be the front line protection for operators and maintenance crews into the future. So, now is the time to consider how light curtains can help your business protect your employees, increase your safety rating, and boost your productivity. To find out more, contact the team at RS, online or phone.

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