Abstract
Purpose: :
To develop a new generation adaptive optics scanning laser ophthalmoscope (AOSLO) that uses a micro–electro–mechanical (MEMS) deformable mirror (DM) and a low coherent light source,, and transfer this imaging modality from the lab bench to clinic.
Methods: :
A compact MEMS DM (Boston Micromachines Corp.), was adopted for use in the AO system. The MEMS DM has an effective optical aperture of 4.4 X 4.4 mm and is driven by 12 X 12 actuators with maximum 3.5 micrometers of stroke. With the miniaturized optical aperture, we were able to design a compact and robust optical system that occupies a 50 cm X 50 cm area on a mobile optical table. A Shack–Hartmann wavefront sensor was used to measure the eye wavefront and supply the feedback control information to the DM for ocular aberration compensation in both the ingoing and outgoing light paths. For different scientific and clinic imaging purposes, two low coherent light sources, which are superluminescent laser diodes (SLD) at 680 nm with 9–nm bandwidth and 840 nm with 50–nm bandwidth, were employed to eliminate the interference artifacts in the images.
Results: :
The MEMS DM based AO system demonstrated robust performance. For a 6 mm diameter pupil, after AO correction, the root–mean–square wave aberration was reduced on average from 0.40 to 0.1 micrometers. The use of low coherent light sources effectively mitigated the interference artifacts in the images and yielded high–fidelity retinal images of the contiguous cone mosaic. Imaging of the cone mosaic has been done on a host of healthy eyes and several eyes with retinal disease.
Conclusions: :
We have implemented the new generation AOSLO with a MEMS DM and low coherence SLDs, and have produced high–fidelity, real–time, microscopic views of the living human retina. The instrument is demonstrated to work effectively for healthy and diseased eyes.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optical properties