Retinal imaging with a low-cost micromachined membrane deformable mirror

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Abstract
Purpose: To study the retina in normal subjects with a high-resolution imaging system using adaptive optics for wave front aberration correction. Methods: We used a low-cost 37-element micromachined membrane deformable mirror (MMDM) with a continuous membrane as the reflective surface. A Hartmann–Shack wave front sensor with cooled charge coupled device camera was used to measure the wave front aberration. Zernike polynomials were used to describe the wave front shape. We developed a mirror control system to compensate for wave aberrations. We tested this instrument in normal subjects. Results: We were able to image the retina in monochromatic laser light and document the increase in resolution. While it is hard to estimate the exact size of the smallest structures in the image, we were able to subjectively grade the image quality. The system is able to compensate for higher order aberrations present in the human eye. Conclusion: The capabilities of correcting ocular aberrations are limited by the number of adjustable elements in the mirror and the deflection range of the surface. The advantage of the MMDM system is its low cost when compared with other adaptive optics solutions such as piezodriven mirrors and spatial light modulators. This technique may allow for improved resolution for clinical fundus photography. © 2002 Society of Photo-Optical Instrumentation Engineers.