基于波前像差纵向分解探测与矫正的活体人眼视网膜AO-OCT技术研究

In vivo human retinal imaging with cellular resolution, which is highly significant for early detection of eye diseases and some body diseases, is seriously affected by ocular aberrations. By introducing adaptive optics (AO) into the retinal imaging systems, the image quality can be observably improved and the retinal cellular structures can be clearly observed. However, current wavefront sensors of AO systems, such as Hartmann-Shack wavefront sensor, can only measure the transversal distribution of wavefront aberrations but cannot provide the depth-resolved wavefront information, and are vulnerable to stray reflections from the optical parts and the imaged targets. As a novel wavefront sensing technique, coherence-gated wavefront sensing (CGWS), which principle is based on optical coherence tomography (OCT), can overcome above limitations. CGWS can work well under strong stray reflections from interface optics such cornea, detect weak signal from objects which is multiplied by the strong signal from reference arm, and reduce the stroke of wavefront corrector and the layout size of imaging system. In this proposal, an adaptive optics optical coherence tomography (AO-OCT) technique for in vivo human retinal imaging with the capability to measure and correct the depth-resolved wavefront aberrations of human eye, will be developed to obtain the high-resolution images in both lateral and axial dimensions of every retinal layers. Combining time-domain CGWS and full-filed OCT techniques, ensures that the measured wavefront aberrations originate only from the layers imaged by the OCT system, and the real-time correction of the wavefront aberrations can thus be achieved in deed. Additionally, by adopting the sinusoidal phase modulation and four integrating buckets (SPM-FIB) to extract the signals from interference patterns for both of CGWS and OCT systems, obviously simplify the system configuration and signal processing. A prototype based on above proposal will be developed and its validity will be verified experimentally by in vivo human retinal imaging. Finally, theoretic and experimental researches on measurement and correction of the depth-resolved wavefront aberrations of human eye will also be done based on the developed prototype to obtain some ideal results and new findings. This research would be useful and promising for the fundamental research and clinical diagnosis of human vision.

视网膜细胞级分辨成像对眼科疾病和部分全身性疾病的早期诊断具有重要意义，但却受人眼像差的影响而不能实现。自适应光学（AO）技术被引入人眼成像领域后，实现了视网膜的细胞级分辨成像。但现有AO系统的波前传感器只能探测像差的横向分布、而对纵向分布无能为力，并易受杂散光干扰。相干门波前传感（CGWS）技术是一种基于光学相干层析成像（OCT）原理的新型波前传感技术，能克服上述问题，具有在强界面反射条件下工作而不受杂散光干扰、增强信号强度、和降低对波前矫正器矫正能力的要求等优点。本项目提出发展一种能对人眼像差进行纵向层析探测与矫正的视网膜AO-OCT技术，来获取视网膜中任意层的高横向和高纵向分辨率图像。具体采用时域CGWS波前探测与全场OCT成像相结合的思路、以及能同时获取二者信息的正弦相位调制四步积分（SPM-FIB）探测法，来建立一套完整的波前像差纵向分解探测与矫正的理论方法、和研制基于此方法的视网膜AO-OCT样机、并通过人眼实验来检验其可行性；最后在此实验平台上开展各种人眼像差纵向层析测量与矫正的理论与实验研究，以期获得完美结果和新发现。本项目的开展，能促进人类视觉基础研究和临床诊断的发展。

视网膜高分辨率成像对眼科和部分全身性疾病的早诊具有重要意义。通过AO技术矫正人眼组织和光学系统的像差后，前述目标才能实现。为克服现有波前传感器对像差的纵向分布不敏感、和易受杂散光干扰等问题，本项目提出发展相干门波前传感（CGWS）技术及基于该技术的人眼AO-OCT成像系统，来对视网膜任意层进行像差测量与矫正、和高分辨率观察。在相干门夏克-哈特曼波前探测技术基础上，我们进一步发展出一种相干门虚拟夏克-哈特曼波前探测技术及基于该技术的AO-OCT成像系统，具体工作包括：人眼像差纵向层析探测与矫正的理论与算法研究；CGWS研制和纵向分解波前像差计算方法研究；基于波前像差纵向层析探测与矫正的视网膜AO-OCT成像技术研究、实验系统研制、和人眼实验研究。.开展本领域共性问题研究，它们的解决有助于获得正确结果和提升效果，因此是本项目的重要组成部分。具体包括：提出了一种简单可行的方法，来矫正人眼AO成像系统存在的成像光与信标光之间的轴向色差，才能实现人眼像差AO矫正之后的高质量成像；提出了一种人眼AO成像系统光功率安全分析方法，考虑了成像光与信标光的光谱带宽及双波段叠加效应，使计算条件与实际相符；提出了共路干涉结构AO-OCT成像技术，来解决现有系统存在的光路长、调节复杂和体积大等问题，有助于显著提升效果和获得全新的AO-OCT系统。作为本项目结构成像向功能成像的拓展、并在开展的全场时域OCT技术基础上，提出了基于全场时域OCT技术的眼底血管造影术，并把其作为后续研究方向。.与国内外大学、公司和医院等，开展了多项学术合作交流，积极参与行业标准制定；发表期刊论文3篇，撰写战略支撑类专著章节1篇，申请发明专利5件，培养研究生4名；提出的两种方法，已在国家重大科学仪器设备开发专项项目“自适应光学高分辨率活体成像仪及其应用”中获得应用。