Which of these engineering controls restricts access to a laser beam?

The protective housing is an engineering control designed to encapsulate a laser beam, thereby preventing direct exposure to the beam and minimizing the risk of accidental exposure. By enclosing the laser source, it restricts access to the laser beam, ensuring that individuals cannot come into contact with or be harmed by the beam during normal operation. This form of control enhances safety by isolating the beam within a designated area, thus significantly reducing the risk of exposure to people who may be near the laser equipment.

In contrast, warning systems, service panels, and training programs play different roles in laser safety. Warning systems are important for alerting individuals to the presence of a hazardous area but do not physically prevent access. Service panels are compartments that may provide access for maintenance but are not designed to restrict access to the beam itself. Training programs are crucial for educating personnel about safe practices and procedures involving lasers, but they do not physically restrict access. Therefore, protective housing directly addresses the need to control access to the laser beam effectively.