Optical scan system (Op Scan)
1. A voting system that can scan paper ballots and tally votes. Most older op scan systems use Infrared (IR) scanning technology and ballots with timing marks to accurately scan the ballot.
Source: Information Technology Terminology, U.S. Election Assistance Commission, https://www.eac.gov/documents/2017/09/21/information-technology-terminology-security
2. System by which votes are recorded by means of marks made in voting response fields designated on one or both faces of a ballot card or series of cards. An optical scan system reads and tabulates ballots, usually paper ballots, by scanning the ballot and interpreting the contents. Also known as Marksense.
Source: Glossary of terms database, U.S. Election Assistance Commission, https://www.eac.gov/glossary/