We developed a clinical ophthalmic prototype by combining bimorph deformable mirror (DM)-based adaptive optics (AO) with a confocal scanning laser ophthalmoscope. A low-cost bimorph DM with a large stroke of 50 μm and an aperture of 20 mm was utilized to realize a strategy for successive AO control of aberration correction, which permitted open-loop compensation for low-order aberrations and closed-loop correction of high-order aberrations to acceptable root mean square errors of <0.08 μm in all subjects. Spherical mirrors were folded in a nonplanar configuration to minimize off-axis aberrations and provide a compact, cost-effective design, which achieved a diffraction-limited performance capable of imaging individual photoreceptor cells and blood vessels not only in healthy subjects but also in patients suffering from retinitis pigmentosa. The adaptive optics scanning laser ophthalmoscope (AOSLO) images of the diseased retina had much higher resolutions than those captured by the commercial AO fundus camera, and loss of the photoreceptor mosaic could be distinguished more accurately due to the improvement in resolution. The compact design and easy handling of the bimorph DM-based AO control may facilitate the translation of AOSLO into clinical settings, and this prototype development will continue with future device refinement and extensive clinical testing.
Proc. SPIE. 8418, 6th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Smart Structures, Micro- and Nano-Optical Devices, and Systems
Using Hartmann-Shack (H-S) wave-front sensor to test lenses with high numerical aperture, the reference spherical
wave-front from pinhole is used to calibrate the Hartmann sensor to improve the precision of calibration, but intensity
uniformity of the reference spherical wave-front affects the precision of Hartmann sensor’s calibration. Based on the
vector diffraction theory, intensity uniformity is calculated with finite-difference time-domain method in case of a
converging Gaussian incident visible light on pinhole. In order to proof the correctness of the intensity model of pinhole
vector diffraction, experimentation of intensity is performed in visible-light. When the pinhole is the material aluminum
with thickness 200nm and pinhole diameter 500nm, the absolute error of intensity uniformity is about 2.57% and 2.31%
within 0.75 NA and 0.5 NA of diffracted wave-front by comparing experiment result with simulation result, so the
intensity model is accurate.
A corneal topography based on Hartmann-Shack Sensor is presented in this paper. In the system, the focus of an
objective lens is precisely positioned on cornea's curve center. Wave-front of the reflecting beam can be measured by the
Hartmann-Shack sensor which is conjugate to the cornea plane. If the corneal surface is a perfect sphere, wave-front
detected by the Hartmann-Shack sensor is a plane. As a result, data measured by Hartmann-Shacks sensor is the
deviation between the sphere and the real cornea surface. This paper describes a methodology for designing instrument
based on Hartmann-Shack sensor. Then, applying this method, an instrument is developed for accurate measurement of
corneal topography. In addition, measuring principle of Hartmann-Shack sensor which determined system
parameters is also introduced. Repeatability is demonstrated by a series of data. The instrument was able to
accurately measure simulative cornea's reflective aberrations, from which corneal topography and corneal refractive
aberrations were derived.