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H. Zhang, C. Alvarez, F. Mueller, J. Bille; Adaptive Optics with Phase Plate Precompensation for the Retina Scanning Closed–Loop System . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4070.
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© ARVO (1962-2015); The Authors (2016-present)
Develop a fast–response, closed–loop, adaptive optical system based on rotating pairs of a phase plate precompensation unit, which could be easily implemented into the human retina tomography instrument. Due to the phase plate precompensation, the dynamic correcting range of this adaptive optical system can be increased.
Statistical human eye aberration distribution is calculated firstly, two pairs of rotating phase plates, typically for the coma and trefoil aberrations, are implemented into the closed–loop adaptive optical system, which is based on the ASIC–Hartman–Shack CMOS sensor or the deformable mirror (OKO membrane mirror or MEMS mirror).To cancel out the unique coma and trefoil aberrations of the human eye, the rotating angle and combination are calculated and applied to drive the phase plates. To control the deformable mirror, influence matrix calculation and the neural network algorithm are tested separately. The behavior of the system is evaluated by RMS value calculation.
It is feasible to correct coma and trefoil aberrations of the human eye by two pairs of rotating phase plates; after phase plate precompensation, the residual higher–order aberrations of human eye are largely reduced, which can be easily compensated further by a deformable mirror. In the adaptive optical system setup, an ASIC–Hartman–Shack CMOS sensor is used, the bandwidth of which is optimized on the hardware level up to 4k Hz. The results show that the introduction of phase plates enhances the CMOS sensor dynamic detecting range, which is one of the major drawbacks compared to the CCD camera.
The implementation of phase plates to the adaptive optical closed–loop system can increase the dynamic compensating range, which would be a method to overcome the deformable mirror correcting limitation. The combination of the ASIC–Hartman–Shack CMOS sensor and the phase plates could be a new fast–response, low–cost part of the high–speed adaptive optical system setup.
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