Study of simultaneous multiple target shot technique for space debris mitigation

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A scheme of space debris mitigation using high-power space-born laser has been proposed. The scheme targets so called small debris that has not been treated before. The scheme uses optical phase conjugation for target acquisition, tracking and targeting with a single optical system. Basic characteristics of Brillouin enhanced four wave mixing as a phase conjugation technique was studied.An initial impact has been calculated to push space debris into the upper atmospheric layer when instantaneous impact is exerted. Required laser energy was also calculated using momentum coupling coefficient, an efficiency of laser energy conversion to momentum of laser ablation. Thus laser pulse energies were estimated necessary to cause large enough orbital deflection to debris. Distance, time of trespassing and energy of deflection were also calculated so that average power that the laser system has to generate can be designed.Wave front control of laser beam then investigated to study the feasibility of the use of phase conjugation for debris acquisition, tracking and targeting. A degree of compensation of wave front distortion caused by various aberrations. The source of aberrations tested include lens, cylindrical lens, random phase plate. For all the aberrations, about 90 % fidelity has been confirmed.Carbon Fluorinert (FG72) that is environmentally safe material was tested as a nonlinear optical medium. Temporal response of the material in terms of holding efficient holographic grating was tested and found to be as high as 100 MHz.In order to realize a debris mitigation system using the phase conjugation technique, multi functional telescope equipped with a convex secondary mirror with concentric diffraction grating was proposed.