Why is the laser beam not visible outdoor?

Construction lasers of the renowned brands are equipped with a laser diode where the light (with the proper usage) is safe for users. For this purpose, the laser light must be weaker than the natural light. Therefore, we cannot see the laser beam outdoor (regardless of its color). For outdoor work with a construction laser, a dedicated sensor should be used (in this case, the laser should be able to cooperate with this kind of sensor). Currently, all offered Nivel System construction lasers have such an option.