|Covid-19|Laser fence Wikipedia
A laser fence is a mechanism to detect objects passing the line of sight between the laser source and the detector. Stronger lasers can potentially be used to injure someone or something passing the laser beam (see mosquito laser).
Sometimes laser fences are used in fiction with the ability to stop intruders by blocking or injuring them.
The Indian Border Security Force (BSF) has implemented a LASER wall system, called LASER Wall, along some parts of its border to stop intrusion.
It is a concept used frequently in videogames. The concepts of these fictional fences can be compared to other concepts like tractor or repulsor beams.