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Scientists from the University of Bath have warned that the public is unwittingly buying dangerous laser pointers which they think are safe but are not. Misleading and mistaken labeling, drastic variations in laser strength under different conditions, and emissions of invisible infrared light all pose risks, the scientists say.

The researchers have responded to a Government consultation on laser pointers calling for better labeling and new easy-to-understand warning signs for all laser pointers. Physicist Dr. Ventsislav Valev, who has experienced a laser pointer attack, and who led tests at the University of Bath on a range of laser pointers, said that their main concern is laser pointers which seem safe to the user but are in fact very powerful. These lasers can lull people into a false sense of security and lead to injury.

Some lasers that are labeled as safe turn out to be highly dangerous because they can emit highly powerful invisible laser light. Moreover, the visible laser power can vary a lot, depending on temperature. Other labels are mistaken, and the maximum power output of the laser is often higher than the safety class on the label, again putting the user and others in danger.

Dr. Valev and PhD student Christian Kuppe in the University of Bath, Department of Physics, collaborated with Dr. Dimitar Slavov from the Bulgarian Academy of Sciences to develop scientific equipment for carefully testing the laser diodes in the heart of every pointer. Their results show that the so-called 'frequency doubled' laser pointers, usually green, blue and violet pointers, can be particularly dangerous even if they seem safe to the user. For example, some laser pointers can output widely different laser power depending on the temperature. They can appear perfectly safe at room temperature only to become much more dangerous outside and vice-versa. Moreover, as pointers are being used they heat up, so a pointer that initially seems safe can subsequently become highly powerful and dangerous.

Other lasers can produce safe levels of colored light, but at the same time emit high power invisible infrared light. A person looking at the visible green light would estimate the laser to be safe and the much greater power and danger would go unnoticed until injury occurs.

Laser pointers have been controversial, in particular because they have been shined into the eyes of plane and helicopter pilots and train drivers, with an average of 1,500 reported attacks per year in the UK. They can cause permanent or temporary eye damage, and it is a criminal offence to do so.