Vacuum valve system having a vacuum valve (40, 40', 40", 40"') for regulating a volume or mass flow and/or for the gas-tight closure of a process volume, wherein the vacuum valve (40, 40', 40", 40'") has • a valve seat which surrounds a valve opening defining an opening axis , • a valve closure , in particular a valve disk, for substantially gas-tight closing of the valve opening and • at least two sealing surfaces , wherein o a first sealing surface of the at least two sealing surfaces is provided by the valve seat and surrounds the valve opening and o a second sealing surface of the at least two sealing surfaces is provided by the valve closure and is formed to correspond with the first sealing surface , • a drive unit which is coupled to the valve closure and is designed in such a way that the valve closure ∘ can be varied and adjusted in a defined manner to provide respective valve opening states, and ∘ is adjustable from an open position (O), in which the valve closure at least partially opens the valve opening , to a closed position, in which the second sealing surface is pressed in the direction of the first sealing surface and the valve opening is closed in a substantially gas-tight manner, and back again, wherein the vacuum valve system has an optical sensor unit , wherein the optical sensor unit is designed for detecting an optical measurement signal, characterized in that the optical sensor unit is arranged and an optical detection axis of the optical sensor unit is aligned such that the measurement signal is measured with respect to at least a part of one of the sealing surfaces , wherein the measurement signal can be generated in a test position of the valve closure and status information can be provided on the basis of the measurement signal with reference to the at least part of one of the sealing surfaces . • a valve seat which surrounds a valve opening defining an opening axis , • a valve closure , in particular a valve disk, for substantially gas-tight closing of the valve opening and • at least two sealing surfaces , wherein o a first sealing surface of the at least two sealing surfaces is provided by the valve seat and surrounds the valve opening and o a second sealing surface of the at least two sealing surfaces is provided by the valve closure and is formed to correspond with the first sealing surface , o a first sealing surface of the at least two sealing surfaces is provided by the valve seat and surrounds the valve opening and o a second sealing surface of the at least two sealing surfaces is provided by the valve closure and is formed to correspond with the first sealing surface , • a drive unit which is coupled to the valve closure and is designed in such a way that the valve closure ∘ can be varied and adjusted in a defined manner to provide respective valve opening states, and ∘ is adjustable from an open position (O), in which the valve closure at least partially opens the valve opening , to a closed position, in which the second sealing surface is pressed in the direction of the first sealing surface and the valve opening is closed in a substantially gas-tight manner, and back again, wherein the vacuum valve system has an optical sensor unit , wherein the optical sensor unit is designed for detecting an optical measurement signal, ∘ can be varied and adjusted in a defined manner to provide respective valve opening states, and ∘ is adjustable from an open position (O), in which the valve closure at least partially opens the valve opening , to a closed position, in which the second sealing surface is pressed in the direction of the first sealing surface and the valve opening is closed in a substantially gas-tight manner, and back again, wherein the vacuum valve system has an optical sensor unit , wherein the optical sensor unit is designed for detecting an optical measurement signal, <EOS>