Performance of a MEMS-based AO-OCT system

Abstract

Adaptive optics (AO) and optical coherence tomography (OCT) are powerful imaging modalities that, when combined, can provide high-resolution, 3-D images of the retina. The AO-OCT system at UC Davis has been under development for 2 years and has demonstrated the utility of this technology for microscopic, volumetric, in vivo retinal imaging. The current system uses a bimorph deformable mirror (DM) made by AOptix Technologies, Inc. for low-order, high-stroke correction and a 140-actuator mirco-electrical-mechanical-system (MEMS) DM made by Boston Micromachines Corporation for high-order correction. We present our on-going characterization of AO system performance. The AO-OCT system typically has residual wavefront error of 100 nm rms. The correctable error in the system is dominated by low-order error that we believe is introduced by aliasing in the control loop. Careful characterization of the AO system will lead to improved performance and inform the design of future systems.

Error budget analysis for an Adaptive Optics Optical Coherence Tomography System

“…Fourier modes are an excellent tool for testing the spatial frequency response of a wavefront reconstructor because they can produce power at all spatial frequencies depending on the sampling of the wavefront. Figure 9 is an example of one individual Fourier mode used for testing [13]. Individual modes, while representative of the error, do not help us quantify the size of the reconstructor error.…”

“…A description of the basic AO operation is available from several previous publications [2, 13]; it is summarized here for the convenience of the reader. There are three modes of operation of the system.…”