A first light source is adapted to illuminate a first object with first light. A first sensor includes a first light receiving element adapted to detect the first light by way of the first object. A second sensor includes a second light receiving element adapted to detect a second light which is externally inputted by way of a second object. A transparent member is disposed on at least one of a first optical path extending from the first object to the first sensor through a first lens and a second optical path extending from the second object to the second sensor through a second lens.