Building hybridized 28-baseline pupil-remapping photonic interferometers for future high-resolution imaging.

One key advantage of single-mode photonic technologies for interferometric use is their ability to easily scale to an ever-increasing number of inputs without a major increase in the overall device size, compared to traditional bulk optics. This is particularly important for the upcoming extremely large telescope (ELT) generation of telescopes currently under construction. We demonstrate the fabrication and characterization of a hybridized photonic interferometer, with eight simultaneous inputs, forming 28 baselines, which is the largest amount to date, to the best of our knowledge. Using different photonic fabrication technologies, we combine a 3D pupil remapper with a planar eight-port ABCD pairwise beam combiner, along with the injection optics necessary for telescope use, into a single integrated monolithic device. We successfully realized a combined device called Dragonfly, which demonstrates a raw instrumental closure-phase stability down to 0.9° over $8\pi$ phase piston error, relating to a detection contrast of ${\sim}6.5 \times {10^{- 4}}$ on an adaptive-optics-corrected 8 m telescope. This prototype successfully demonstrates advanced hybridization and packaging techniques necessary for on-sky use for high-contrast detection at small inner working angles, ideally complementing what can currently be achieved using coronagraphs.

Laboratory demonstration of a cryogenic deformable mirror for wavefront correction of space-borne infrared telescopes.

This paper demonstrates a cryogenic deformable mirror (DM) with 1020 actuators based on micro-electrical mechanical systems (MEMS) technology. Cryogenic space-borne infrared telescopes can experience a wavefront error due to a figure error of their mirror surface, which makes the imaging performance worse. For on-orbit wavefront correction as one solution, we developed a MEMS-processed electro-static DM with a special surrounding structure for use under the cryogenic temperature. We conducted a laboratory demonstration of its operation in three cooling cycles between 5 K and 295 K. Using a laser interferometer, we detected the deformation corresponding to the applied voltages under the cryogenic temperature for the first time. The relationship between voltages and displacements was qualitatively expressed by the quadratic function, which is assumed based on the principle of electro-static DMs. We also found that it had a high operating repeatability of a few nm root-mean-square and no significant hysteresis. Using the measured values of repeatability, we simulated the improvement of the point spread function (PSF) by wavefront correction with our DM. These results show that our developed DM is effective in improving imaging performance and PSF contrast of space-borne infrared telescopes.

Characterization of fluoride fibers for the Optical Hawaiian Array for Nanoradian Astronomy project.

We report on the interferometric characterization of a pair of 300 m long single-mode non-polarization-maintaining fibers designed for the Optical Hawaiian Array for Nanoradian Astronomy ('OHANA) project whose goal is to realize a kilometric near-infrared astronomical array by connecting the large telescopes of the Mauna Kea observatory with single-mode fibers. The fluoride glass fibers are operated in the astronomical K band (2.0-2.4 microm) in which their attenuation is low. We have measured very low differential chromatic dispersion, and the wideband fringe visibility is 0.9 if the two fiber arms have the same temperature. The thermal sensitivity of fibers with respect to their interferometric properties has been studied. The differential chromatic dispersion of the fibers is highly sensitive to the temperature difference. On the contrary, the coherent loss due to mismatch of polarization states is not significantly dependent on the temperature difference. Compensation of thermally induced differential dispersion by use of CaF2 glass plates is demonstrated.

Comparative molecular active site analysis (CoMASA). 1. An approach to rapid evaluation of 3D QSAR.

We have developed a rapid evaluation method, comparative molecular active site analysis (CoMASA), for obtaining 3D QSAR. CoMASA has three major advantages: (1) the CoMASA results would easily transform to pharmacophore and/or queries required for 3D database searches, (2) the CoMASA method is not required to consider orientation and translation of molecules against a lattice, and (3) standard PCs can be used to perform the analysis. The potential of these improvements and possible further enhancements are discussed.

Rapid evaluation of molecular shape similarity index using pairwise calculation of the nearest atomic distances.

Rapid evaluation method for obtaining molecular shape similarity index using pairwise calculation of the nearest atomic distance respected to the template atoms was investigated. This method for calculations of similarity indices remarkably reduced required time compared with hitherto methods (especially 2 or 3 orders of magnitude faster than the previous grid-based evaluation technique) and gave without clear loss of preciseness. The potential of these improvements and possible further enhancements are discussed.