Ultrasound attenuation spectroscopy, instead of energy, the attenuation coefficient is measured versus frequency
Neutral density filter (ND) with an attenuation factor of 4, or simply ND4
Inductive sensors evaluate the attenuation of a high-frequency electro-magnetic field which has been generated by eddy currents in the work piece.
Finally, and perhaps most importantly, fiberoptic cables are essentially 100% efficient in optical transmission, having an attenuation less than 10 dB per kilometer.