Optimization of the open-loop liquid crystal adaptive optics retinal imaging system

Area of Science:

• Ophthalmology
• Biomedical Engineering
• Optical Sciences

Background:

• Adaptive optics (AO) systems are crucial for high-resolution retinal imaging.
• Liquid crystal spatial light modulators (LC-SLMs) are used as wavefront compensators in AO systems.
• Dispersion in LC-SLMs necessitates careful system design for aberration detection and imaging.

Purpose of the Study:

• To develop an open-loop AO system for retinal imaging with an expanded field of view (FOV).
• To improve the FOV without sacrificing aberration detection accuracy.
• To evaluate the performance of the developed AO system in terms of correction precision and image quality.

Main Methods:

• Constructed an open-loop AO system utilizing an LC-SLM for wavefront compensation.
• Integrated a modified mechanical shutter to control the illumination spot size on the fundus, expanding the FOV.
• Operated the AO loop in a pulsing mode, illuminating the fundus twice per correction cycle.
• Evaluated correction precision in a closed-loop configuration, measuring residual error and Strehl ratio.
• Tested the system on two subjects with myopia (-3D and -5D).

Main Results:

• Achieved an increased FOV of 1.7 degrees for retinal imaging.
• Maintained aberration detection accuracy despite the expanded FOV.
• Demonstrated a residual error of approximately 0.0909λ (RMS) and a Strehl ratio of 0.7217 in closed-loop evaluation.
• Obtained high-resolution images of retinal capillaries and photoreceptors in subjects.

Conclusions:

• The developed open-loop AO system effectively expands the FOV for retinal imaging.
• The pulsing AO loop strategy enhances FOV without compromising performance.
• The system demonstrates high correction precision and yields excellent image quality, suitable for detailed retinal imaging in myopic individuals.