The double door airlock interlocking technology  is used in safety and
security critical applications where not only access authority but also
positive proof of identity is required before granting access.

An automated door interlocking is a physical access control solution
comprising of a space between two interlocking doors.
One door must be closed and locked before the second door is permitted to open.
Electrical Interlock is fail safe and maintains cleanroom integrity
by preventing both doors from being opened at the same time.