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Super‐resolution bright‐field optical microscopy based on nanometer topographic contrast

By using an expectation‐maximization maximum likelihood estimation algorithm to improve the lateral resolution of a recently developed non‐interferometric wide‐field optical profilometer, we obtain super‐resolution bright‐field optical images of nanometer features on a flat surface. The optical profilometer employs a 365‐nm light source and an ordinary objective lens of a 0.95 numerical aperture. For objects of 100 nm thickness, lateral features about λ/7 can be resolved in the restored images without fluorescence labeling. Current image acquisition rate is 0.1 frame/sec, which is limited by the brightness of the light source. With a brighter light source, the imaging speed can be fast enough for real‐time observation of dynamic activities in the nanometer scale. Microsc. Res. Tech. 65:180–185, 2004. © 2005 Wiley‐Liss, Inc.