For the simplest blinding system, it is advised to use wavelengths that are transmitted into the eye, but are beyond the visible spectrum region. The enemy soldier is unaware of the existence of this invisible electromagnetic radiation, so he does not protect himself. Since the eye is transparent to these wavelengths in the Near-Infra-Red (NIR), this radiation is focused on the retina, and burns it.
The fact that the eye does not sense this radiation prevent the activation of the natural human defense (the blinking reflex when high light intensity is pointed on the eye).

It is relatively simple to protect soldiers against these blinding lasers by giving them goggles with filters that transmit only visible spectrum. Such goggles does not disturb regular vision, and can also be used to protect sensitive optical instruments.

A more sophisticated blinding laser system operates within the visible spectrum, and use tunable laser. It is difficult to design protection against such lasers, because a filter that will block visible light will not allow the soldier to see.

Many solutions are now in development, such as special coatings on the goggles, which change their transmission properties very fast (in less than a nanosecond) when high power light hit them. These coatings transform from the transparent stage into a non-transparent (blocking) stage.

A big discussion about the use of lasers for blinding was held in 1996-7 at international conventions, because they defined it as "inhuman weapon" (?!). The final decision was that it can be used against terrorists, but not against soldiers. Thus, blinding lasers and the counter-measures against them are continue to be developed.