Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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Real-time Image-based Autofocus

AutofocusBlurring correctionOptical system


The invention consists of an autofocus system capable of providing a fast, robust and flexible correction of the blurring of an optical system.

Technical features

The patented system allows to correct the blurring by measuring the mutual lateral displacement between two images of the same field of view, obtained from the rays passing through different portions of the pupil. These two images are recorded with two-dimensional sensors, and the two-dimensional digital images thus obtained can be aligned using standard two-dimensional alignment methods. In this way, the method allows measuring defocus in real-time, using only the image captured by the optical apparatus, without the need to project auxiliary rays on the sample and without long optimization procedures.

Possible Applications

  • Wide-field microscopy;
  • Light-sheet microscopy;
  • Optical imaging of biological samples;
  • Microscopy for industry (e.g. quality control);
  • Imaging and photography.


  • Real-time autofocus, based on the image actually collected and not on different interactions with the sample (e.g. reflections);
  • Robust against sample-induced aberrations;
  • Robust in samples with sparse content.