Optimizing Image Quality in Non-Confocal AOSLO Imaging Using a Dynamically Reconfigurable Aperture Pattern
PATHAK B., SHAH M., YOUNG L., SMITHSON H.
In an adaptive optics scanning laser ophthalmoscope (AOSLO), directly back scattered light is collected by placing a pinhole conjugate to the retinal plane, which allows visualisation of the photoreceptor mosaic. By collecting the multiply-scattered non-confocal light, images of other retinal structures can be obtained using different detection geometries: darkfield imaging (summing the non-confocal light) has been used to visualise retinal pigment epithelium cells; split-detection imaging (differential imaging by dividing the non-confocal light into two halves) has been used to visualise photoreceptor inner segments; and offset-aperture imaging (displacing the confocal pinhole) has been used to visualise vessel walls and retinal ganglion cells. In the present work, we use a digital micromirror device (DMD) and exploit its reconfigurability to perform both the confocal and non-focal imaging. We realise different imaging modalities by displaying different patterns (aperture configurations) on the DMD. Aperture configuration is defined using different parameters, such as: inner diameter, outer diameter and orientation. Information from the Shack-Hartmann wavefront sensor is used to optimise the pattern on the DMD. We present preliminary experimental results to demonstrate the programmable aperture control to obtain improved split-detection images.