We studied the superiority of two different control methods for adaptive optics using the Shack-Hartmann Wave-Front Sensors (SHWFS) using a compact AO system (CRAO), which were developed at the Koyama Astronomical Observatory of Kyoto Sangyo University. Direct Gradient Control (DGC) method experimentally derives a control matrix that directly converts slope vectors to DM voltage vectors. Zernike Modal Control (ZMC) method generates a control matrix with two reconstruction matrices in modal representation for a Deformable Mirror (DM) and wavefront slope vectors obtained from the SHWFS images.We simulated the various atmospheric conditions with windspeed at r0=3.7cm by laboratory experiments and investigated the AO performances (FWHM and residual WFE) between these two methods.The results showed that at wind speeds V>12m/s, there was no difference among the methods, and the temporal error was dominant. V<12m/s, ZMC method performance improves as the number of Fringe Zernike terms, and it was found that the use of up to 36 terms produces better performance than DGC method. The reason for the worse DGC method was found to be that the applied voltage calculated for the TT-arm is large and the PSF is not stable.
We have developed a new non-contact profiler which can measure aspherical mirrors including freeform surfaces. One of the best features of this instrument is its very wide dynamic range of 0.01 to 100 μm, while maintaining interferometerlevel measurement precision. It utilizes Computer-Generated Holograms (CGH) for generating the arbitrary wavefront. The wide dynamic range is achieved by integrating two modes, “Interferometer Mode" and "Hartmann Mode," which can be switched by changing the internal optical path without the need to move the measurement mirror. The measurement accuracy is 0.0053 μm RMS in Interferometer Mode and 0.055 μm RMS in Hartmann Mode. The Interferometer Mode provides a measurable dynamic range from 0.0053 to 31 μm, while the Hartmann Mode extends from 0.055 to 625 μm when measuring a spherical surface of F-number 1.0.
We demonstrate a conceptual design for a high-resolution infrared spectrograph, the Dark Matter Quest Spectrograph: DMQS, dedicated to detecting dark matter. A crucial standout of the DMQS is it is not optimized for typical astronomical observations but for searching for dark matter. Although it is a relatively simple setup compared to some other competitive instruments and facilities, some of which have billion-dollar budgets, only a few nights’ observation with the DMQS and a small telescope with F/10 will enable to detect the faintest signal from dark matter to date for its observable mass range of dark matter. The DMQS’s compatibility with small telescopes also increases the chance of long-term observations, further improving its sensitivity to search for dark matter.
Compact refractive adaptive optics (CRAO) is a visible compact adaptive optics (AO) system optimized for small telescopes. It was mounted on the 1.3 m Araki telescope of Koyama Astronomical Observatory (KAO) in Kyoto Sangyo University, Japan. CRAO aims to improve the natural seeing 3” to 0.8” at 500 nm at the KAO site. Thus, it needs a large format and highly frequent camera for wide field survey (WFS) and a largely segmented depth map (DM) because the natural seeing ∼3” at the KAO site is especially poor for astronomical observations. To improve the performance of CRAO with a new WFS and DM, we searched for the optimal AO parameters (the number of WFS subapertures (NWFS), the number of DM actuators (NDM), and the loop frequency (fL) with two AO simulators using yao and COMPASS. Consequently, we found that NWFS > 12×12, NDM > 80, and fL > 800 Hz are necessary to achieve the full width at half maximum (FWHM) < 0.8” for point spread function (PSF) under the KAO site’s atmospheric conditions. Finally, we calculated the limiting magnitude (Vlim) with commercially available sensors for WFS and DMs. By combining ORCA-Lightning (Hamamatsu Photonics) and DM97-15 (ALPAO), a deeper limiting magnitude (Vlim ∼ 4.4) can be achieved, even with a 1 m-class telescope.
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