Results of the project from Russian scientific foundation
2015 fundamental research is presented by laboratory experiments of interaction investigation of femtosecond laser radiation and sea water including organic matter in diverse forms and phytoplankton cells.
Space, time and spectral characteristics of filaments in the time of laser radiation spread with impulse duration about 120 fs on the wave length of 532 nm and impulse energy up to 23 mJ (in order to investigate Raman scattering and fluorescence) and laser radiation with central wave length of 800 nm, impulse duration was about 40 fs, energy in the impulse was up to 3mJ (in order to investigate filamnetation process and optic breakdown). Intensity has been changed in wide limits in order to measure characteristics of scattering radiation which interacts with environments in different regimes. The investigation was done from intensity when spontaneous Raman scattering and organic matter fluorescence to induced scattering and following breakdown was observed. Important changes of parameters of water Raman scattering and chlorophyll A fluorescence lines were registered.
Results of this investigation are made to improve laser monitoring of sea water and laser sounding new methods. Applied part of this project is development of hardware and software complexes of underwater environment monitoring, sea surface and complexes carries (remotely operated vehicles, autonomous underwater vehicles and unmanned aerial vehicles). ROV “Arctic force” and AUV “Nimble” were developed and tested.
UAV was designed and developed in order to install hardware and software complex of sea surface sounding, this UAV is developed to carry available load and provide necessary energy to measure ice thickness and sound by laser a sea surface. The main task was to develop appropriate (available load up to 5 kg) equipment to provide remote measurement of ice thickness via Unmanned Aerial Vehicle. So the hardware base of electromagnetic measurement system of ice thickness is micro single chip of broadband radar transceiver (Novelda – NVA-6100). Receipt and radiation of broadband signal is carried out by Vivaldi antennas (band of effective radiation and receipt is up to 5 GHz). Measurements are based on the classic geo radar method of ice thickness sounding where sounding impulse is video impulse of less than nanosecond duration. Such impulse has high penetration capability in dielectric environment (some meters of sea ice) and special resolution of several millimeters. Ice thickness is expressed as L= Vt/2, where V is for group velocity of impulse spread in ice, t is for time of impulse spread from upper layer of the ice to bottom and back to the top.
Measurement system appraises group velocity by well-known method of common depth point, so the system is equipped with another Vivaldi-antenna. This project also includes development of technical requirements and specification of software for remote operative control of measurement system and post processing of data. The structure of channel is developed in order to provide communication between measurement system of ice thickness and vessel. Components of the communication channel module is purchased and delivered. Methods of ice thickness measurement by UAV are developed, velocity of UAV in the time of measurement is determined also. Main characteristics of electromagnetic measurement of ice thickness are as follows: - ice thickness to be measured 0.05 - 3 m; - measurement error of ice thickness measurement < 20 km/h (limited by communication channel); - flight altitude of UAV in the time of measurement < 3 kg; - energy consumption < 3 Watt.
2015 development of laser spectrometer was finished in order to measure spectrums of laser induced fluorescence of underwater environment. Laboratory test of the spectrometer was done, minimum detectable concentrations of chlorophyll-A, dissolved organic matter, oil hydrocarbons was appraised, so now it is possible to register them by spectrometer of laser induced fluorescence.