Fig. 1. Flow chart of quasi-3D fluorescence spectrum parallel acquisition method based on software lock-in amplification technique

Fig. 2. Schematic diagram of light path of laser induced fluorescent lidar

Fig. 3. Prototype of laser induced fluorescence lidar

Fig. 4. Lock-in amplification principle

Fig. 5. Software lock-in amplification system based on Simulink

Fig. 6. Fluorescence spectra of planktic algae directly collected. (a) Sunlight background; (b) dark background

Fig. 7. Results of phase locking amplification of Chlorella fluorescence excited by different wavelengths under sunlight. (a) 405 nm; (b) 465 nm; (c) 520 nm; (d) 638 nm

Fig. 8. Fluorescence spectra of planktic algae excited by different wavelengths after lock-in amplification under sunlight background. (a) 405 nm; (b) 465 nm; (c) 520 nm; (d) 638 nm

Fig. 9. Normalized results of fluorescence spectra of different algae. (a) Aps; (b) Aigp; (c) Acv; (d) Ancm