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1. Beam geometry, alignment, and wavefront aberration effects on interferometric differential wavefront sensing

   https://doi.org/10.1088/0957-0233/26/12/125203  

   Yu, Xiangzhi; Gillmer, S R; Ellis, J D (December 2015, Measurement Science and Technology)
2. Accurate and noise-robust wavefront reconstruction with an optical vortex wavefront sensor

   https://doi.org/10.1364/OE.581032  

   Korzeniewska, Aleksandra K; Łukowicz, Magdalena; Kalinowski, Kamil; Cichowski, Rafał; Porras-Aguilar, Rosario; Szatkowski, Mateusz (January 2026, Optics Express)

   The term wavefront sensor refers to the entire class of devices capable of measuring the optical wavefront of the incoming beam. Although numerous solutions have been proposed so far, recent advances in structured light have opened new development possibilities through controlled modification of optical field amplitude and phase. We present an alternative approach to angle-based sensing, introducing optical vortices, stable phase singularities, within each subaperture of the Shack-Hartmann (S-H) architecture. Rather than changing the fundamental angle-based operating principle, it transforms the tracked quantity and its detection method. The presence of a singularity enables a dedicated tracking algorithm that outperforms conventional methods without increasing computational complexity. We evaluated its performance against the conventional S-H across a broad SNR range, demonstrating lower RMS wavefront error across all conditions. This work demonstrates that structured beam shaping can extend the capabilities of traditional S-H architectures without requiring fundamental redesign. 

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3. Metasurface-in-the-Middle Attack: EM Wavefront Manipulation Threats and Countermeasures

   https://doi.org/10.1109/TON.2025.3629689  

   Shaikhanov, Zhambyl; Hassan, Fahid; Guerboukha, Hichem; Mittleman, Daniel M; Knightly, Edward W (January 2026, IEEE Transactions on Networking)

   Metasurfaces enable controllable manipulation of electromagnetic waves and have been shown to be valuable for wireless communications in many diverse ways. In this paper, we explore the notion that these useful components could also provide opportunities for a malicious agent. In particular, we define and experimentally demonstrate for the first time a “MetaSurface-in-the-Middle” (MSITM) attack. In this attack, the adversary Eve places a metasurface in the path of a directive transmission between Alice and Bob and targets to re-direct a portion of the signal towards herself, without being detected. Specifically, we show how Eve can design a metasurface that induces abrupt phase changes at the interface of the metasurface to controllably diffract directional links and establish furtive eavesdropping links. We explore the theoretical foundations of the MSITMattack and demonstrate that an effective metasurface can be prototyped in under 5 min at a minimal cost. We experimentally demonstrate the attack in a THz time-domain system and perform a set of over-the-air experiments. Our results indicate that the MSITM attack yields an acute vulnerability that can significantly reduce empirical secrecy capacity while leaving a minimal energy footprint, making the attack challenging to detect. 

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4. A near-infrared pyramid wavefront sensor for the MMT

   https://doi.org/10.1117/12.2629419  

   Taylor, Jacob; Sivanandam, Suresh; Anugu, Narsireddy; Butko, Adam; Chen, Shaojie; Durney, Olivier; Hardy, Tim; Lamb, Masen; Montoya, Manny; Morzinski, Katie M.; et al (August 2022, Proceedings of the SPIE)

   Schmidt, Dirk; Schreiber, Laura; Vernet, Elise (Ed.)

   The MMTO Adaptive optics exoPlanet characterization System (MAPS) is an ongoing upgrade to the 6.5-meter MMT Observatory on Mount Hopkins in Arizona. MAPS includes an upgraded adaptive secondary mirror (ASM), upgrades to the ARIES spectrograph, and a new AO system containing both an optical and near-infrared (NIR; 0.9-1.8 μm) pyramid wavefront sensor (PyWFS). The NIR PyWFS will utilize an IR-optimized double pyramid coupled with a SAPHIRA detector: a low-read noise electron Avalanche Photodiode (eAPD) array. This NIR PyWFS will improve MAPS's sky coverage by an order of magnitude by allowing redder guide stars (e.g. K & M-dwarfs or highly obscured stars in the Galactic plane) to be used. To date, the custom designed cryogenic SAPHIRA camera has been fully characterized and can reach sub-electron read noise at high avalanche gain. In order to test the performance of the camera in a closed-loop environment prior to delivery to the observatory, an AO testbed was designed and constructed. In addition to testing the SAPHIRA's performance, the testbed will be used to test and further develop the proposed on-sky calibration procedure for MMTO's ASM. We will report on the anticipated performance improvements from our NIR PyWFS, the SAPHIRA's closed-loop performance on our testbed, and the status of our ASM calibration procedure. 

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5. Reference Wave Design for Wavefront Sensing

   https://doi.org/10.1109/ICCP51581.2021.9466263  

   Chen, Wei-Yu; Levin, Anat; O'Toole, Matthew; Sankaranarayanan, Aswin C. (May 2021, IEEE International Conference on Computational Photography (ICCP))

   null (Ed.)