Imaging acousto-optic tunable filter with 0.35-micrometer spatial resolution

Image blur in acousto-optic tunable filters (AOTF's) has been a persistent problem. Here we describe the connection between transducer structure and image blur and experimentally measure it by using a 5-cm 12°-cut TeO(2) crystal of our design. With these quantitative results, we develop an image-processing method that minimizes AOTF-related image degradation. The combination of long crystal design and image processing results in substantially improved image contrast and spatial resolution relative to conventional AOTF imaging devices. We present high-magnification images of fluorescent actin fibers in cells in which we obtain a resolution of approximately 0.35 μm, representing the first successful use of an AOTF for ultra-high-resolution microscopy. Further improvements are also predicted.