Retinal axial focusing and multi-layer imaging with a liquid crystal adaptive optics camera

Adaptive optics (AO) systems are widespread and considered as an essential part of any large aperture telescope for obtaining a high resolution imaging at present. To enlarge the imaging field of view (FOV), multi-laser guide stars (LGSs) are currently being investigated and used for the large aperture optical telescopes. LGS measurement is necessary and pivotal to obtain the cumulative phase distortion along a target in the multi-LGSs AO system. We propose a high precision phase reconstruction algorithm to estimate the phase for a target with an uncertain turbulence profile based on the interpolation. By comparing with the conventional average method, the proposed method reduces the root mean square (RMS) error from 130 nm to 85 nm with a 30% reduction for narrow FOV. We confirm that such phase reconstruction algorithm is validated for both narrow field AO and wide field AO.

Section: Resultsmentioning

confidence: 99%

A high precision phase reconstruction algorithm for multi-laser guide stars adaptive optics

et al. 2016

“…The AO system is now considered to be an essential setup of many new large aperture optical telescopes. [3,4] In traditional adaptive optics, the distortion is measured by a wavefront sensor (WFS) and corrected by a wavefront corrector (WFC), such as a deformable mirror (DM) [5] or liquid crystal wavefront corrector (LCWC), [6][7][8][9][10][11][12][13] conjugated to the telescope pupil. [14,15] Unfortunately, this approach only achieves a good imaging resolution within a limited field of view (FOV) smaller than the isoplanatic angle that is generally only a few arc-seconds at visible wavelengths.…”

Section: Introductionmentioning

confidence: 99%

Configuration optimization of laser guide stars and wavefront correctors for multi-conjugation adaptive optics

et al. 2016

Self Cite

Multi-conjugation adaptive optics (MCAOs) have been investigated and used in the large aperture optical telescopes for high-resolution imaging with large field of view (FOV). The atmospheric tomographic phase reconstruction and projection of three-dimensional turbulence volume onto wavefront correctors, such as deformable mirrors (DMs) or liquid crystal wavefront correctors (LCWCs), is a very important step in the data processing of an MCAO's controller. In this paper, a method according to the wavefront reconstruction performance of MCAO is presented to evaluate the optimized configuration of multi laser guide stars (LGSs) and the reasonable conjugation heights of LCWCs. Analytical formulations are derived for the different configurations and are used to generate optimized parameters for MCAO. Several examples are given to demonstrate our LGSs configuration optimization method. Compared with traditional methods, our method has minimum wavefront tomographic error, which will be helpful to get higher imaging resolution at large FOV in MCAO.

“…There is no reference discussing how to determine the capillary imaging position. Usually, researchers determine the capillary imaging position by searching for a retinal capillary image by moving the detector backward or forward [15,16] or using optical coherence tomography (OCT) [17] to achieve retinal tomography images. But these cannot capture the CL for different human eyes.…”

Section: Introductionmentioning

confidence: 99%

Determining the imaging plane of a retinal capillary layer in adaptive optical imaging

Yang

et al. 2016

Even in the early stage, endocrine metabolism disease may lead to micro aneurysms in retinal capillaries whose diameters are less than 10 µm. However, the fundus cameras used in clinic diagnosis can only obtain images of vessels larger than 20 µm in diameter. The human retina is a thin and multiple layer tissue, and the layer of capillaries less than 10 µm in diameter only exists in the inner nuclear layer. The layer thickness of capillaries less than 10 µm in diameter is about 40 µm and the distance range to rod&cone cell surface is tens of micrometers, which varies from person to person. Therefore, determining reasonable capillary layer (CL) position in different human eyes is very difficult. In this paper, we propose a method to determine the position of retinal CL based on the rod&cone cell layer. The public positions of CL are recognized with 15 subjects from 40 to 59 years old, and the imaging planes of CL are calculated by the effective focal length of the human eye. High resolution retinal capillary imaging results obtained from 17 subjects with a liquid crystal adaptive optics system (LCAOS) validate our method. All of the subjects' CLs have public positions from 127 µm to 147 µm from the rod&cone cell layer, which is influenced by the depth of focus.