Ptychography with OAM beams

Light beams possessing orbital angular momentum (OAM) are characterized by distinctive amplitude and phase structures. We were able to investigate how such a peculiar illumination, combined with optical aberrations, enhances the quality of ptychographic images obtained at the FERMI FEL source.   


Pancaldi et al., Optica, Vol. 11 - 3, pp. 403-411 (2023).

Ptychography with OAM beams

After performing single-shot per position ptychography experiments with a test object, we demonstrate an improvement of more than one order of magnitude in spatial resolution and beam stability compared to previously reported FEL results in the EUV range.

We observe a clear trend relating the achieved image resolution with the OAM topological charge order ℓ: the higher the ℓ value, the better the image resolution and quality.

Moreover, the beam characterization, performed through the ptychographic reconstruction of the illumination probes, confirms that OAM beams are very sensitive to optical aberrations, which distort the beam transversal profile compared to ideal Laguerre–Gaussian intensity patterns.

Our findings are relevant for the design of fully single-shot FEL-based ptychographic imaging experiments exploiting OAM light, since the use of high ℓ values can maximize the beneficial effects of the non-ideality of the illumination function determined by residual beam aberrations.

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High-resolution ptychographic imaging at a seeded free-electron laser source using OAM beams.

Pancaldi M., Guzzi F., Bevis C.S., Manfredda M., Barolak J., Bonetti S., Bykova I., De Angelis D., De Ninno G., Fanciulli M., Novinec L., Pedersoli E., Ravindran A., Rösner B., David C., Ruchon T., Simoncig A., Zangrando M., Adams D.E., Vavassori P., Sacchi M., Kourousias G., Mancini G.F., Capotondi F.

Optica, Vol. 11 - 3, pp. 403-411 (2023).

DOI: 10.1364/OPTICA.509745

Last Updated on Monday, 25 March 2024 17:58