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    Engineering an achromatic Bessel beam using a phase-only spatial light modulator and an iterative Fourier transformation algorithm
    (Amsterdam [u.a.] : Elsevier, 2016) Walde, Marie; Jost, Aurélie; Wicker, Kai; Heintzmann, Rainer
    Bessel illumination is an established method in optical imaging and manipulation to achieve an extended depth of field without compromising the lateral resolution. When broadband or multicolour imaging is required, wavelength-dependent changes in the radial profile of the Bessel illumination can complicate further image processing and analysis. We present a solution for engineering a multicolour Bessel beam that is easy to implement and promises to be particularly useful for broadband imaging applications. A phase-only spatial light modulator (SLM) in the image plane and an iterative Fourier Transformation algorithm (IFTA) are used to create an annular light distribution in the back focal plane of a lens. The 2D Fourier transformation of such a light ring yields a Bessel beam with a constant radial profile for different wavelength.
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    Successful optimization of reconstruction parameters in structured illumination microscopy
    (Amsterdam [u.a.] : Elsevier, 2019) Karras, Christian; Smedh, Maria; Förster, Ronny; Deschout, Hendrik; Fernandez-Rodriguez, Julia; Heintzmann, Rainer
    The impact of the different reconstruction parameters in super-resolution structured illumination microscopy (SIM) on image artifacts is carefully analyzed. These parameters comprise the Wiener filter parameter, an apodization function, zero-frequency suppression and modifications of the optical transfer function. A detailed investigation of the reconstructed image spectrum is concluded to be suitable for identifying artifacts. For this purpose, two samples, an artificial test slide and a more realistic biological system, were used to characterize the artifact classes and their correlation with the image spectra as well as the reconstruction parameters. In addition, a guideline for efficient parameter optimization is suggested and the implementation of the parameters in selected up-to-date processing packages (proprietary and open-source) is depicted. © 2018 The Authors