A scanning visible-super-resolution microscope based on the saturation behaviour of
transient fluorescence detected infrared (TFD-IR) spectroscopy is proposed. A Gaussian
IR beam, a Gaussian visible beam and a Laguerre-Gaussian (LG) visible beam are Used
to obtain two separate two-color excitation fluorescence (2CF) images of the sample.
The final image is obtained as the difference between the two recorded images. If
the peak intensity of the LG beam is high enough to induce saturation in the fluorescence
signal, the image can, in principle, have unlimited spatial resolution. A similar
to 3-fold improvement in transverse resolution over the visible diffraction limit
(and far exceeding the IR diffraction limit) is easily achievable in present experimental
setups. (C) 2009 Elsevier B.V. All rights reserved.