| 摘要 |
The device detects the density of a film 4 particularly when development is complete; it comprises a source 5 emitting a ray of given energy, whose wavelength has no effect on the sensitive part of the film, capable of being placed on one side of the film; a receiver 6 sensitive to the emitted ray and capable of being placed on the other side of the film 4; circuits 12, 13, 14 for fixing a given energy threshold beforehand; a circuit 10 for comparing the energy received by the said receiver 6 with the said given energy threshold; and a warning system 15, 16 activated by the said comparator circuit 10 when the energy of the received ray reaches the said given threshold. <IMAGE>
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