An adjustable wrench includes a fixed jaw, a movable jaw slidably disposed in the fixed jaw, a movable member disposed in the fixed jaw for driving the movable jaw to move, a handle pivoted on the fixed jaw for being pivoted back and forth relative to the fixed jaw, a stop pin and a switch post. To increase the reliability of examination of the spectral characteristic of the luminescence light, it is provided that the detector units are disposed one behind the other with respect to the luminescence light emitted by the document. The bridge fittings may be mounted within a channel of a backing plate for structural support.