| 摘要 |
A device for producing and detecting a gap-shaped parallel pencil of light rays, including a light source (1) and detecting members (9) of a suitable known kind, such as phototransistors for detecting the rays which may have passed through an object to be measured (18), comprises a first shielding member (2) having a mirroring layer (4) facing the light source (1), and a gap (5) where said mirroring layer (4) has been removed. A further characterizing feature is that a second shielding member (8) is located between said first shielding member (2) and said detecting members (9), said second shielding member (8) having at least one shielding layer (10,11) with at least one gap (12,14), substantially aligning with the gap (5), of the layer (4) of the first shielding member (2), and said detecting members (9), and that the shielding members (2,8) are spaced from each other, so that a space (17) is formed therebetween, into which space (17) an object to be measured (18), for example a banknote (18), is intended to be inserted. <IMAGE> |
