Design of the measuring circuit for the content of crude oil in seawater

Abstract

It has been demonstrated that there must be a linear relation between fluorescence intensity and concentration of crude oil in seawater. Since the fluorescence signal is strong weakness and is also affected by the ambient light & stray light, it must be extremely difficult or almost impossible to detect based on convention ways. In this paper, a new approach for the detection of the weak fluorescence signal by the programmable gain of digital lock-in amplifier (PG-DLIA). The proposed scheme which comprise of the 255 nm LED trigger to excite the seawater to produce fluorescent signal, and the high sensitivity photodiode as detector to perceive of the faint fluorescent signal. In particular, the feeble fluorescence signal is well detected through the circuit of PG-DLIA. In terms of the laboratory experiment and sea trial, the sensor of crude oil in seawater with this circuit has the advantages of simple structure, lower consumption, portable, modular, high precision, real time and continuity. It will have vast application prospects on the detection of weak signals.