For other uses, see Scanner (disambiguation).
Retinal scanners are wall-mounted electronic lock systems typically connected to secured entrances. Authorized individuals can unlock these doors by having their eyes scanned, verifying their identities in the process. To operate the device, users must peer into the visor and remain still for a brief period while the scan commences.
In Half-Life, scanners in the Black Mesa Research Facility are often found near security checkpoints being operated by security guards. Some science facilities such as the Anomalous Materials Laboratory in Sector C also require scanner use, the apparatuses here being used by the science team. If the user isn't authorized to enter, the automated announcement system will report that access is denied. It's said that new employees must submit their identity to the retinal clearance system at the Black Mesa Personnel Department before being permitted into the high-security branch of the transit system.
In Blue Shift, hand scanners are present in the Section A-17 Prototype Labs, an older section of the facility. Dr. Rosenberg states these are part of the old security system which instead recognizes users by their fingerprint ID.
In Half-Life 2, a retinal scanner is used by Dr. Kleiner in his lab to access the teleportation room. Initially hidden inside a column, its secret compartment is revealed by adjusting the nearby Black Mesa research team group photograph. This scanner emits the same sounds as a Combine Camera.
In Half-Life, scanners are usually found in levels that feature escort missions where the player is required to lead a character to the device to open further paths, such as in the chapter Questionable Ethics. The game ends and loads the last save game file if the player fails to protect the character.
In his letter of acceptance to Black Mesa, Gordon Freeman was told that he wouldn't immediately need to submit to a retinal scan for the outset of his employment. He is therefore unable to himself use the scanners that are encountered throughout the game. Other Black Mesa employee protagonists are able to operate scanners.
 Behind the scenes
 Half-Life and its expansions
Being used inside the Alien Research Labs.
 Half-Life 2
 List of appearances
- Half-Life: Day One (First appearance)
- Half-Life: Opposing Force
- Half-Life: Blue Shift
- Half-Life: Decay
- Half-Life 2