Adaptive system for eye-fundus imaging

Larichev, A. V.; Ivanov, Pavel; Iroshnikov, N. G.; Shmal'gauzen, V I; Otten, Leonard John

doi:10.1070/qe2002v032n10abeh002314

Cited by 23 publications

(11 citation statements)

References 11 publications

(15 reference statements)

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“…Various types of dynamic wavefront correctors have hence been applied to the eye. Bimorph mirrors [24,25] having 13-35 actuators have been investigated by several groups [3][4][5]14,15]. Recently, Fernandez et al [29] evaluated a magnetic membrane mirror with 52 actuators.…”

Section: Introductionmentioning

confidence: 99%

Requirements for discrete actuator and segmented wavefront correctors for aberration compensation in two large populations of human eyes

et al. 2007

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Numerous types of wavefront correctors have been employed in adaptive optics (AO) systems for correcting the ocular wavefront aberration. While all have improved image quality, none have yielded diffraction-limited imaging for large pupils (≥6 mm), where the aberrations are most severe and the benefit of AO the greatest. To this end, we modeled the performance of discrete actuator, segmented piston-only, and segmented piston/tip/tilt wavefront correctors in conjunction with wavefront aberrations measured on normal human eyes in two large populations. The wavefront error was found to be as large as 53 μm, depending heavily on the pupil diameter (2-7.5 mm) and the particular refractive state. The required actuator number for diffraction-limited imaging was determined for three pupil sizes (4.5, 6, and 7.5 mm), three second-order aberration states, and four imaging wavelengths (0.4, 0.6, 0.8, and 1.0 μm). The number across the pupil varied from only a few actuators in the discrete case to greater than 100 for the piston-only corrector. The results presented will help guide the development of wavefront correctors for the next generation of ophthalmic instrumentation.

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Section: Introductionmentioning

confidence: 99%

Requirements for discrete actuator and segmented wavefront correctors for aberration compensation in two large populations of human eyes

et al. 2007

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“…Recent applications include super-resolution fundus imagers [3][4][5][6][7][8], as well as the integration of AO with ophthalmic instruments like the Scanning Laser Ophthalmoscope (SLO) [9,10] and the Optical Coherence Tomograph (OCT) [11], where it offers new capabilities for the early detection and diagnosis of retinal diseases. In parallel with the medical applications of AO for vision science, there has also been a great interest in the psychophysics of supernormal vision [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Characterization for vision science applications of a bimorph deformable mirror using phase-shifting interferometry

Horsley

Park

Laut

et al. 2005

Ophthalmic Technologies XV

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The wave front corrector is one of the three key elements in adaptive optics, along with the wave front sensor and the control computer. Low cost, compact deformable mirrors are increasingly available. We have tested the AOptix bimorph deformable mirror, originally developed for ultra-high bandwidth laser communication systems, to determine its suitability for vision science applications, where cornea and lens introduce optical aberrations. Measurements of the dynamic response of the mirror to a step input were obtained using a commercial Laser Doppler Vibrometer (LDV). A computer-controlled Twyman-Green interferometer was constructed to allow the surface height of the deformable mirror to be measured using Phase-Shifting Interferometry as a function of various control voltages. A simple open-loop control method was used to compute the control voltages required to generate aberration mode shapes described by the Zernike polynomials. Using this method, the ability of the deformable mirror to generate each mode shape was characterized by measuring the maximum amplitude and RMS error of each Zernike mode shape up to the fifth radial order. The maximum deformation amplitude was found to diminish with the square of the radial order of the Zernike mode, with a measured deformation of 8 microns and 1.5 microns achieved at the second-order and fifth-order Zernike modes, respectively. This deformation amplitude appears to be sufficient to allow the mirror to correct for aberrations up to the fifth order in the human eye.

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“…Macroscopic discrete actuator deformable mirrors, e.g., such as those manufactured by Xinetics 20 , have been used in various imaging modalities [2][3][4]8,10 . The use of micromachined membrane DMs 21-23 , bimorph [5][6][7]24 , liquid crystal spatial light modulators 9,25-28 and microelectromechanical systems (MEMS) 29,30 have also been reported. Dalimier and Dainty compared the performance of three commercial correctors (one bimorph, a membrane mirror and a piezoelectric mirror) 31 .…”

Section: Introductionmentioning

confidence: 98%

Wavefront corrector requirements for compensation of ocular aberrations in two large populations of normal human eyes

et al. 2006

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Numerous types of wavefront correctors have been employed in adaptive optics (AO) systems for correcting the wave aberrations of the eye. While each has been shown to reduce the degrading impact of the ocular aberrations, none have shown sufficient correction to yield diffraction-limited imaging for large pupils (≥ 6 mm), where the aberrations are most severe and the benefit of AO is largest. As the wavefront corrector appears to be the limiting AO component, it raises a fundamental concern as to what characteristics of this device, in particular actuator stroke and number, are required to achieve diffraction-limited imaging, and to optimally match corrector performance and cost to that required of a particular imaging task in the eye. In this paper, we model the performance of discrete actuator deformable mirrors, piston-only segmented mirrors, and piston/tip/tilt segmented mirrors in conjunction with wavefront aberrations measured on human eyes in two large population datasets (University of Rochester and Indiana University). The actuator stroke and number required to achieve diffraction-limited imaging for a 7.5 mm pupil were found to be highly dependent on the level of 2 nd order aberrations and the population considered. Specifically, the required stroke for encompassing 95% of the population ranged from 12-53 (Rochester) and 7-11 (Indiana) microns. The wide range resulted from whether 2 nd order aberrations were corrected or set to zero prior to correction. To achieve a Strehl > 0.8, the actuator number across the pupil diameter ranged from >14 (Rochester) and 11-14 (Indiana) for discrete actuator deformable mirrors, >95 (Rochester) and 50-90 (Indiana) for piston-only segmented mirrors, and finally 12-19 (Rochester) and 9-10 (Indiana) for piston/tip/tilt segmented mirrors.

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Adaptive system for eye-fundus imaging

Cited by 23 publications

References 11 publications

Requirements for discrete actuator and segmented wavefront correctors for aberration compensation in two large populations of human eyes

Requirements for discrete actuator and segmented wavefront correctors for aberration compensation in two large populations of human eyes

Characterization for vision science applications of a bimorph deformable mirror using phase-shifting interferometry

Wavefront corrector requirements for compensation of ocular aberrations in two large populations of normal human eyes

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