In recent years, fluorescence microscopy has been revolutionized. Reversible switching of fluorophores has enabled circumventing the limits imposed by diffraction. Thus, resolution down to the molecular scale became possible. However, to the best of our knowledge, the application of the principles underlying superresolution fluorescence microscopy to reflection microscopy has not been experimentally demonstrated. Here, we present the first evidence that this is indeed possible. A layer of photochromic molecules referred to as the absorbance modulation layer (AML) is applied to a sample under investigation. The AML-coated sample is then sequentially illuminated with a one-dimensional (1D) focal intensity distribution (similar to the transverse laser mode TEM01) at wavelength λ 1 = 325 nm to create a subwavelength aperture within the AML, followed by illumination with a Gaussian focal spot at λ 2 = 633 nm for high-resolution imaging. Using this method, called absorbance modulation imaging (AMI) in reflection, we demonstrate a 2.4-fold resolution enhancement over the diffraction limit for a numerical aperture (NA) of 0.65 and wavelength (λ) of 633 nm.

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ZusammenfassungIn diesem Beitrag präsentieren wir die Fertigung polymerer, diskret gestufter spiraler optischer Phasenplatten (SPPs) für die Erzeugung von Ringmoden in Laserstrahlen. Wir beschreiben das von uns verwendete Modell um die Wirkung von SPPs im Fernfeld abhängig von ihrer Geometrie zu simulieren und diese zu dimensionieren. Weiter berichten wir von der Fertigung zunächst 3- und 4-stufiger SPPs aus dem Negativlack AZ nLOF 2070 auf Kalk-Natron-Glas durch Spin Coating und Polymerisation mittels direkter Laserlithografie. Wir zeigen die Wirkung der Bauteile auf das Strahlprofil eines Helium-Neon-Lasers im Fernfeld und validieren damit auch das verwendete Modell.