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| Main Authors: | , , , , , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2603.27193 |
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| _version_ | 1866908918934929408 |
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| author | Agazzi, Costanza Toledo-García, Nick Martín-Badosa, Estela Montes-Usategui, Mario Maluenda, David Tiana-Alsina, Jordi Martínez-Herrero, Rosario Carnicer, Artur |
| author_facet | Agazzi, Costanza Toledo-García, Nick Martín-Badosa, Estela Montes-Usategui, Mario Maluenda, David Tiana-Alsina, Jordi Martínez-Herrero, Rosario Carnicer, Artur |
| contents | Fluorescence depletion microscopy techniques such as STED and RESOLFT require optical fields with a well-defined and spatially confined central intensity minimum to achieve sub-diffraction lateral resolution. Here, we present the design and experimental implementation of an azimuthally polarized, doughnut-shaped depletion beam based on super-pupil engineering principles. By tailoring the radial amplitude distribution at the entrance pupil to approximate a Bessel-type target function, the resulting focal field exhibits a tighter central doughnut compared to conventional azimuthally polarized beams. The designed pupil field distribution is implemented using a phase-only spatial light modulator operated in a double pass configuration, enabling independent modulation of orthogonal polarization components via complex-field holographic encoding. Experimental characterization using sub-diffraction fluorescent beads demonstrates a reduction of the peak-to-peak distance of the central doughnut by approximately 16% relative to a nominal azimuthally polarized reference beam. Although the engineered field exhibits pronounced sidelobes, these do not preclude its use as a depletion beam, since lateral resolution is strongly influenced by the spatial confinement and effective suppression of the central intensity minimum for a given depletion intensity. This suggests that the proposed approach can enable improved lateral resolution at comparable depletion powers, providing a flexible and experimentally accessible route for engineering depletion fields in reconfigurable super-resolution microscopy systems. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2603_27193 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Azimuthal super-pupil beam engineering for improved fluorescence depletion microscopy Agazzi, Costanza Toledo-García, Nick Martín-Badosa, Estela Montes-Usategui, Mario Maluenda, David Tiana-Alsina, Jordi Martínez-Herrero, Rosario Carnicer, Artur Optics Fluorescence depletion microscopy techniques such as STED and RESOLFT require optical fields with a well-defined and spatially confined central intensity minimum to achieve sub-diffraction lateral resolution. Here, we present the design and experimental implementation of an azimuthally polarized, doughnut-shaped depletion beam based on super-pupil engineering principles. By tailoring the radial amplitude distribution at the entrance pupil to approximate a Bessel-type target function, the resulting focal field exhibits a tighter central doughnut compared to conventional azimuthally polarized beams. The designed pupil field distribution is implemented using a phase-only spatial light modulator operated in a double pass configuration, enabling independent modulation of orthogonal polarization components via complex-field holographic encoding. Experimental characterization using sub-diffraction fluorescent beads demonstrates a reduction of the peak-to-peak distance of the central doughnut by approximately 16% relative to a nominal azimuthally polarized reference beam. Although the engineered field exhibits pronounced sidelobes, these do not preclude its use as a depletion beam, since lateral resolution is strongly influenced by the spatial confinement and effective suppression of the central intensity minimum for a given depletion intensity. This suggests that the proposed approach can enable improved lateral resolution at comparable depletion powers, providing a flexible and experimentally accessible route for engineering depletion fields in reconfigurable super-resolution microscopy systems. |
| title | Azimuthal super-pupil beam engineering for improved fluorescence depletion microscopy |
| topic | Optics |
| url | https://arxiv.org/abs/2603.27193 |