共查询到20条相似文献,搜索用时 15 毫秒
1.
An artificial dynamic eye model is proposed. The prototype enabled us to introduce temporal variations in defocus and spherical aberration, resembling those typically found in the human eye. The eye model consisted of a meniscus lens together with a modal liquid crystal lens with controllable focus. A diffuser placed at a fixed distance from the lenses acted as the artificial retina. Developed software allowed the user to precisely control the dynamic generation of aberrations. In addition, different refractive errors could simultaneously be emulated by varying the distance between the components of the model. The artificial eye was first used as a dynamic generator of both spherical aberration and defocus, imitating the behavior of a real eye. The artificial eye was implemented in an adaptive optics system designed for the human eye. The system incorporated an electrostatic deformable mirror and a Hartmann-Shack wavefront sensor. Results with and without real time closed-loop aberration correction were obtained. The use of the dynamic artificial eye could be quite useful for testing and evaluating adaptive optics instruments for ophthalmic applications. 相似文献
2.
全光路像差校正自适应光学系统中共模波前传感器标定方法研究 总被引:2,自引:0,他引:2
根据光波在介质中的传播规律,首先详细分析了全光路像差校正自适应光学系统的工作原理,然后对常规方法标定共模波前传感器后的系统校正残余误差作了分析,并从校正残余误差和操作的简易程度两个方面分析了常规方法标定共模波前传感器存在的缺点,最后针对全光路像差校正自适应光学系统的特点,提出了两种新的共模波前传感器标定方法,详细推导了两种方法标定共模波前传感器后全系统的校正残余误差.结果显示,两种方法标定共模波前传感器后,其校正残余误差只与常规方法标定共模波前传感器后系统的校正残余误差中的一种误差有关. 相似文献
3.
Wanek JM Mori M Shahidi M 《Journal of the Optical Society of America. A, Optics, image science, and vision》2007,24(5):1296-1304
The effect of increased high-order wavefront aberrations on image resolution was investigated, and the performance of adaptive optics (AO) for correcting wavefront error in the presence of increased light scatter was assessed in a model eye. An AO section imaging system provided an oblique view of a model retina and incorporated a wavefront sensor and deformable mirror for measurement and compensation of wavefront aberrations. Image resolution was quantified by the width of a Lorentzian curve fitted to a laser line image. Wavefront aberrations were significantly reduced with AO, resulting in improvement of image resolution. In the model eye, image resolution was degraded with increased high-order wavefront aberrations (horizontal coma and spherical) and improved with AO correction of wavefront error in the presence of increased light scatter. The findings of the current study suggest that AO imaging systems can potentially improve image resolution in aging eyes with increased aberrations and scatter. 相似文献
4.
Chen DC Jones SM Silva DA Olivier SS 《Journal of the Optical Society of America. A, Optics, image science, and vision》2007,24(5):1305-1312
Adaptive optics scanning laser ophthalmoscopes have been used to produce noninvasive views of the human retina. However, the range of aberration compensation has been limited by the choice of deformable mirror technology. We demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human eye while maintaining the quality of the retinal imagery. We verified experimentally that the use of dual deformable mirrors improved the dynamic range for correction of the wavefront aberrations compared with the use of the micro-electro-mechanical-system mirror alone and improved the quality of the wavefront correction compared with the use of the bimorph mirror alone. We also demonstrated that the large-stroke bimorph deformable mirror improved the capability for axial sectioning with the confocal imaging system by providing an easier way to move the focus axially through different layers of the retina. 相似文献
5.
Booth MJ 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2007,365(1861):2829-2843
The imaging properties of optical microscopes are often compromised by aberrations that reduce image resolution and contrast. Adaptive optics technology has been employed in various systems to correct these aberrations and restore performance. This has required various departures from the traditional adaptive optics schemes that are used in astronomy. This review discusses the sources of aberrations, their effects and their correction with adaptive optics, particularly in confocal and two-photon microscopes. Different methods of wavefront sensing, indirect aberration measurement and aberration correction devices are discussed. Applications of adaptive optics in the related areas of optical data storage, optical tweezers and micro/nanofabrication are also reviewed. 相似文献
6.
光学系统仿真软件Seelight是一款可以模拟光束产生、大气传输与自适应光束控制等光学系统的具有自主知识产权的系统仿真软件,为光学系统应用研究提供了有效的仿真工具。本文首先介绍了Seelight软件的基本构架、运行界面和主要模型库包含的模块,并利用自适应光学相关的基本模型搭建了自适应光学仿真系统,模拟了PZT变形镜模块和哈特曼波前波传感器模块构成自适应光学仿真系统通过校正光束大气传输的波前畸变来提高远场光斑的光束质量的过程。验证了在不同的湍流强度下,自适应光学仿真系统的校正效果随着湍流强度的增加,校正残差大幅增加。利用Seelight软件可以对包含自适应光学系统的各种光学系统进行仿真建模,并可以对系统进行有效的验证分析和优化设计。
相似文献7.
Adaptive optics systems often work in a closed-loop configuration due to the hysteretic and nonlinearity properties of conventional deformable mirrors. Because of the high-precision wavefront generation and nonhysteretic properties of liquid-crystal devices, the open-loop control becomes possible. Open-loop control is a requirement for advanced adaptive optics concepts. We designed an open-loop adaptive optics system with a liquid-crystal-on-silicon wavefront corrector. This system is simple, fast, and can save much more light compared to conventional liquid-crystal-based closed-loop systems. The detailed principle, construction, and operation are discussed. The 500 m horizontal turbulence correction experiment was done using a 250 mm telescope in the laboratory. The whole system can reach a 60 Hz correction frequency. Evaluation of the correction precision was done at closed-loop configuration, which is 0.2 lambda (lambda=0.633 microm) in peak to valley. The dynamic image under open-loop correction got the same resolution compared to closed-loop correction. The whole system reached 0.68 arc sec resolution capability at open-loop correction, which is slightly larger than the system's diffraction-limited resolution of 0.65 arc sec. 相似文献
8.
K.M. Hampson 《Journal of Modern Optics》2013,60(21):3425-3467
It has long been recognised that the optical quality of the human eye is far from diffraction limited. This affects our visual acuity and severely limits the resolution at which images of the living retina can be obtained. Adaptive optics is a technique that can correct for the eye's aberrations and provide diffraction limited resolution. The origins of the technique lie in astronomy, but it was successfully adapted to the human eye just over 10 years ago. Since then there have been rapid developments in the field of adaptive optics and vision science. In vivo images of the retina can now be routinely achieved with unprecedented resolution. Sophisticated experiments can be performed to gain a deeper knowledge of the interaction of neural retinal architecture and visual perception. This article presents the theory behind adaptive optics for the human eye and reviews the developments in this field to date. 相似文献
9.
Ocular aberration correction can significantly improve visual function of the human eye. However, even under ideal aberration correction conditions, pupil diffraction restricts the resolution of retinal images. Pupil filtering is a simple super-resolution (SR) method that can overcome this diffraction barrier. In this study, a 145-element piezoelectric deformable mirror was used as a pupil phase filter because of its programmability and high fitting accuracy. Continuous phase-only filters were designed based on Zernike polynomial series and fitted through closed-loop adaptive optics. SR results were validated using double-pass point spread function images. Contrast sensitivity was further assessed to verify the SR effect on visual function. An F-test was conducted for nested models to statistically compare different CSFs. These results indicated CSFs for the proposed SR filter were significantly higher than the diffraction correction (p < 0.05). As such, the proposed filter design could provide useful guidance for supernormal vision optical correction of the human eye. 相似文献
10.
高功率固体板条激光器的光束质量严重受限于增益介质热效应等多种因素。如何同时获得高平均功率和高光束质量是激光发展过程中面临的一个基本物理问题。自适应光学技术能够有效补偿固体板条激光系统输出光束的静态和动态像差,是改善光束质量的有效手段。近年来中国科学院光电技术研究所掌握了低阶像差补偿器、加权优化波前复原方法、通用波前处理机等关键技术,为国内多个固体板条激光系统研制了二十余套自适应光学光束净化系统,显著改善了光束质量,保障了上述激光系统的有效运用。
相似文献11.
人眼像差哈特曼测量仪的重复性测试 总被引:1,自引:1,他引:0
人眼像差哈特曼测量仪利用 Hartmann-Shack 波前传感器探测波前,并用 Zernike 多项式实现波前的重建。测试结果的重复性对该仪器来说是至关重要的。此仪器对模拟人眼静态像差和活体人眼动态像差分别进行单帧采集和连续采集,所得的模拟人眼静态像差 Zernike 系数的标准偏差的最大值,PV 与 RMS 依次为 0.016?,0.061?和 0.006?;活体人眼动态像差 Zernike 系数的标准偏差的最大值,PV 与 RMS 依次为 0.045?,0.167? 和 0.030?,这些指标都小于 ?/5,表明该仪器具有较高的重复性。 相似文献
12.
The European Southern Observatory (ESO) is studying the next generation giant telescope, called the European Extremely Large Telescope (E-ELT). With a 42?m diameter primary mirror, it is a significant step from currently existing telescopes. Therefore, the E-ELT with its instruments poses new challenges in terms of cost and computational complexity for the control system, including its adaptive optics (AO). Since the conventional matrix-vector multiplication (MVM) method successfully used so far for AO wavefront reconstruction cannot be efficiently scaled to the size of the AO systems on the E-ELT, faster algorithms are needed. Among those recently developed wavefront reconstruction algorithms, three are studied in this paper from the point of view of design, implementation, and absolute speed on three multicore multi-CPU platforms. We focus on a single-conjugate AO system for the E-ELT. The algorithms are the MVM, the Fourier transform reconstructor (FTR), and the fractal iterative method (FRiM). This study enhances the scaling of these algorithms with an increasing number of CPUs involved in the computation. We discuss implementation strategies, depending on various CPU architecture constraints, and we present the first quantitative execution times so far at the E-ELT scale. MVM suffers from a large computational burden, making the current computing platform undersized to reach timings short enough for AO wavefront reconstruction. In our study, the FTR provides currently the fastest reconstruction. FRiM is a recently developed algorithm, and several strategies are investigated and presented here in order to implement it for real-time AO wavefront reconstruction, and to optimize its execution time. The difficulty to parallelize the algorithm in such architecture is enhanced. We also show that FRiM can provide interesting scalability using a sparse matrix approach. 相似文献
13.
Understanding peripheral optical errors and their impact on vision is important for various applications, e.g. research on myopia development and optical correction of patients with central visual field loss. In this study, we investigated whether correction of higher order aberrations with adaptive optics (AO) improve resolution beyond what is achieved with best peripheral refractive correction. A laboratory AO system was constructed for correcting peripheral aberrations. The peripheral low contrast grating resolution acuity in the 20° nasal visual field of the right eye was evaluated for 12 subjects using three types of correction: refractive correction of sphere and cylinder, static closed loop AO correction and continuous closed loop AO correction. Running AO in continuous closed loop improved acuity compared to refractive correction for most subjects (maximum benefit 0.15?logMAR). The visual improvement from aberration correction was highly correlated with the subject's initial amount of higher order aberrations (p?=?0.001, R 2?=?0.72). There was, however, no acuity improvement from static AO correction. In conclusion, correction of peripheral higher order aberrations can improve low contrast resolution, provided refractive errors are corrected and the system runs in continuous closed loop. 相似文献
14.
IntroductionActivemirorsareindispensableelementsforadaptiveoptics[1].Recentadvancesofthemicromachinedmembranedeformablemiror(... 相似文献
15.
基于脉动阵列的自适应光学实时波前处理机设计 总被引:1,自引:0,他引:1
针对自适应光学系统对波前处理机高计算量、高实时性的要求,本文提出了一种基于脉动阵列的自适应光学实时波前处理方法.该方法将脉动阵列的概念引入波前处理机设计,完成了波前斜率计算、复原运算和控制运算向脉动阵列的映射,合理地建立了数据的深度流水线,同时分析了以FPGA技术实现时系统的计算延时.对于48个子孔径,61单元的自适应光学系统,以一片Xilinx Virex-Ⅱ XC2V3000芯片实现了基于脉动阵列的实时波前处理机,实验测得计算延时仅8.6μs,结果表明该方法能极大地提高系统的实时性,集成度、通用性和扩展性. 相似文献
16.
Efficient parallel adaptive aberration correction 总被引:1,自引:0,他引:1
Krishnan S Rigby KW O'Donnell M 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》1998,45(3):691-703
Previous studies have shown that the parallel adaptive receive compensation algorithm (PARCA) can improve clinical images of the abdomen degraded by aberrations. Corrected images show both improved contrast resolution and overall image quality. However, PARCA is very computationally intensive and, consequently, cannot be easily implemented in real-time. In this study, modifications to PARCA for possible real-time implementation are explored. A modified algorithm, PARCA2 (parallel adaptive receive compensation algorithm 2), is introduced to perform aberration correction much more efficiently. Results from tissue-mimicking phantoms and human images show that corrections with PARCA2 rival that of PARCA. 相似文献
17.
A collimator with a long focal length and large aperture is a very important apparatus for testing large-aperture optical systems. But it suffers from internal air turbulence, which may limit its performance and reduce the testing accuracy. To overcome this problem, an adaptive optics system is introduced to compensate for the turbulence. This system includes a liquid crystal on silicon device as a wavefront corrector and a Shack-Hartmann wavefront sensor. After correction, we can get a plane wavefront with rms of about 0.017 lambda (lambda=0.6328 microm) emitted out of a larger than 500 mm diameter aperture. The whole system reaches diffraction-limited resolution. 相似文献
18.
Microlenses have been characterized by a digital holographic microscopy system, which is immune to the inherent wavefront aberration. The digital holographic microscopy system takes advantage of fiber optics and uses the light emitted directly from a single-mode fiber as the recording reference wave. By using such a reference beam, which is quasi-identical to the object beam, the inherent wavefront aberration of the digital holographic microscope is removed. The alignment of the optical setup can be optimized with the help of numerical reconstruction software to give the system phase with the off-axis tilt removed. There is one, and only one, reference fiber point position to give a reference wavefront that is quasi-identical to the object wavefront where the system is free of wavefront aberration and directly gives the quantitative phase of the test object without the need for complicated numerical compensation. 相似文献
19.
BICGSTAB算法在波前重构和控制中的应用 总被引:2,自引:0,他引:2
自适应光学波前重构和控制对精度和实时性的要求很高。BICGSTAB算法可用于非正定对称的线性系统方程的求解,并且速度快、精度高,稳定性好。基于Fried网格,提出将BICGSTAB算法引入自适应光学波前重构和控制系统方程的求解,并与SVD以及几种常见的迭代算法(Jacobi,Seidel,SOR以及SSOR)作比较。仿真结果表明,对于121阶系统,BICGSTAB法达到0.01%精度仅仅需要不到70次的迭代;SVD法达到0.01%需要近300次;四种常见迭代方法即使104次也没有收敛。这说明BICGSTAB具有更高的速度和精度,能够更好地满足自适应光学系统实时性和精度的需要。 相似文献