Abstract: There is provided a variable width optical slit mechanism capable of controlling the width of a slit with high accuracy in wide range of temperatures. A pair of conductive carriages is movably mounted on a conductive guide rail in the state that the carriages are not in contact with the guide rail by use of insulative rolling elements, or alternatively, a pair of conductive carriages is movably mounted on an insulative guide rail by use of conductive rolling elements. A pair of slit forming members is mounted to the pair of carriages, respectively. An elastic force is given to the carriages for energizing them such that they move toward each other, thereby to always bring the slit forming members into contact with each other to make the width of a slit zero. When a slit is formed, the carriages move away from each other against the elastic force.

Abstract: There is provided a variable width optical slit mechanism capable of controlling the width of a slit with high accuracy in wide range of temperatures. A pair of conductive carriages is movably mounted on a conductive guide rail in the state that the carriages are not in contact with the guide rail by use of insulative rolling elements, or alternatively, a pair of conductive carriages is movably mounted on an insulative guide rail by use of conductive rolling elements. A pair of slit forming members is mounted to the pair of carriages, respectively. An elastic force is given to the carriages for energizing them such that they move toward each other, thereby to always bring the slit forming members into contact with each other to make the width of a slit zero. When a slit is formed, the carriages move away from each other against the elastic force.