The photonic lantern (PL) is a tapered waveguide that can efficiently couple light into multiple singlemode optical fibers. Such devices are currently being considered for a number of tasks, including the coupling of telescopes and highresolution, fiberfed spectrometers, coherent detection, nulling interferometry, and vortexfiber nulling. In conjunction with these use cases, PLs can simultaneously perform loworder focalplane wavefront sensing. In this work, we provide a mathematical framework for the analysis of a PL wavefront sensor (PLWFS), deriving linear and higherorder reconstruction models as well as metrics through which sensing performance—in both the linear and nonlinear regimes—can be quantified. This framework can be extended to account for additional optics such as beamshaping optics and vortex masks, and can be generalized for other wavefront sensing architectures. Finally, we provide initial numerical verification of our mathematical models by simulating a sixport PLWFS. In a forthcoming companion paper (Lin and Fitzgerald), we provide a more comprehensive numerical characterization of fewport PLWFSs, and consider how the sensing properties of these devices can be controlled and optimized.
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Free, publiclyaccessible full text available September 14, 2023

One of the top priorities in observational astronomy is the direct imaging and characterization of extrasolar planets (exoplanets) and planetary systems. Direct images of rocky exoplanets are of particular interest in the search for life beyond the Earth, but they tend to be rather challenging targets since they are ordersofmagnitude dimmer than their host stars and are separated by small angular distances that are comparable to the classical
$\mathrm{\lambda <\#comment/>}/D$ diffraction limit, even for the coming generation of 30 m class telescopes. Current and planned efforts for groundbased direct imaging of exoplanets combine highorder adaptive optics (AO) with a stellar coronagraph observing at wavelengths ranging from the visible to the midIR. The primary barrier to achieving high contrast with current direct imaging methods is quasistatic speckles, caused largely by noncommon path aberrations (NCPAs) in the coronagraph optical train. Recent work has demonstrated that millisecond imaging, which effectively “freezes” the atmosphere’s turbulent phase screens, should allow the wavefront sensor (WFS) telemetry to be used as a probe of the optical system to measure NCPAs. Starting with a realistic model of a telescope with an AO system and a stellar coronagraph, this paper provides simulations of several closely related regression models that take advantagemore » 
Abstract We present the direct imaging discovery of a lowmass companion to the nearby accelerating F star, HIP 5319, using SCExAO coupled with the CHARIS, VAMPIRES, and MEC instruments in addition to Keck/NIRC2 imaging. CHARIS
JHK (1.1–2.4μ m) spectroscopic data combined with VAMPIRES 750 nm, MECY , and NIRC2L _{p}photometry is best matched by an M3–M7 object with an effective temperature ofT = 3200 K and surface gravity log(g ) = 5.5. Using the relative astrometry for HIP 5319 B from CHARIS and NIRC2, and absolute astrometry for the primary from Gaia and Hipparcos, and adopting a lognormal prior assumption for the companion mass, we measure a dynamical mass for HIP 5319 B of , a semimajor axis of ${31}_{11}^{+35}{M}_{\mathrm{J}}$ au, an inclination of ${18.6}_{4.1}^{+10}$ degrees, and an eccentricity of ${69.4}_{15}^{+5.6}$ . However, using an alternate prior for our dynamical model yields a much higher mass of ${0.42}_{0.29}^{+0.39}$ . Using data taken with the LCOGT NRES instrument we also show that the primary HIP 5319 A is a single star in contrast to previous characterizations of the system as a spectroscopic binary. This work underscores the importance of assumed priors in dynamical models for companions detected with imaging andmore » ${128}_{88}^{+127}{M}_{\mathrm{J}}$ 
The success of groundbased, high contrast imaging for the detection of exoplanets in part depends on the ability to differentiate between quasistatic speckles caused by aberrations not corrected by adaptive optics (AO) systems, known as noncommon path aberrations (NCPAs), and the planet intensity signal. Frazin (ApJ, 2013) introduced a postprocessing algorithm demonstrating that simultaneous millisecond exposures in the science camera and wavefront sensor (WFS) can be used with a statistical inference procedure to determine both the series expanded NCPA coefficients and the planetary signal. We demonstrate, via simulation, that using this algorithm in a closedloop AO system, realtime estimation and correction of the quasistatic NCPA is possible without separate deformable mirror (DM) probes. Thus the use of this technique allows for the removal of the quasistatic speckles that can be mistaken for planetary signals without the need for new optical hardware, improving the efficiency of groundbased exoplanet detection. In our simulations, we explore the behavior of the Frazin Algorithm (FA) and the dependence of its convergence to an accurate estimate on factors such as Strehl ratio, NCPA strength, and number of algorithm search basis functions. We then apply this knowledge to simulate running the algorithm in realtime in a nearlymore »

We are building a nextgeneration laser adaptive optics system, RoboAO2, for the UH 2.2m telescope that will deliver robotic, diffractionlimited observations at visible and nearinfrared wavelengths in unprecedented numbers. The superior Maunakea observing site, expanded spectral range and rapid response to highpriority events represent a significant advance over the prototype. RoboAO2 will include a new reconfigurable natural guide star sensor for exquisite wavefront correction on bright targets and the demonstration of potentially transformative hybrid AO techniques that promise to extend the faintness limit on current and future exoplanet adaptive optics systems.