Brother HL-L2300D Service Manual page 13

 Additional Information
When servicing the optical system of the machine, be careful not to place a screwdriver or
other reflective object in the path of the laser beam. Be sure to take off any personal
accessories such as watches and rings before working on the machine. A reflected beam,
though invisible, can permanently damage the eyes.
Since the beam is invisible, the following caution in print is attached on the laser unit.
In print
x
Confidential