**4. Conclusions**

shows the typical images of Sunspot 1492 with the AO off and AO on respectively, on the May 28 run. For the AO off images, the AO still provides the tip-tilt correction, so that the overall image movement is corrected. Compared with the poor image quality when the AO is switch‐ ed off, the AO system provides significant improvement for the image quality when the AO is switched on, which demonstrates the power of the AO correction: the granules around the sunspot can be clearly seen with the AO correction, while they are totally blurred and disap‐ peared without the correction. The AO off image clearly shows how poor the seeing condi‐ tion was during our observation run. In the observation, only 7x7 sub-apertures were used for the WFS, and only 1.0-meter of the McMP aperture was used for imaging, because a small area on the edge of the telescope primary mirror was damaged and the telescope heliostat was tilted at a large angle during the observation, which delivered an useful circle aperture on the order of 1.0-meter in diameter. Each sub-aperture was sampled by 30x30 pixels of the WFS camera. The AO delivered an open-loop bandwidth of 800 Hz, which corresponds to a closedloop bandwidth of ~ 80 Hz. The improvement of image performance with the AO correction was significant. This was the first time demonstration that an AO system can be effectively

**Figure 5.** PSAO setup (the black breadboard) on the McMP rotation station. The two red cameras are used for WFS

**Figure 6.** Sunspot 1492 image captured on the McMP with the AO off (left) and AO on (right).

used for high-resolution imaging in the visible with the McMP.

and TTS, while the grey one is the science camera.

36 Adaptive Optics Progress

We have fully demonstrated the feasibility of a portable AO system, both in the laboratory and on-site observations. The system is able to provide a wave-front correction with differ‐ ent telescopes with the aperture size up to 1.6 meters. Our AO system features low cost, high-performance, and is compact. Combining the multi-core computer and LabVIEW par‐ allel programming, the AO system is particularly flexible and can achieve good perform‐ ance. The open-loop correction speed can achieve 800Hz with sub-pixel accuracy for wavefront sensing, for the 7x7 sub-aperture WFS when 25 modes of Zernike polynomials of the wave-front are corrected. It can further achieve 1100 Hz, if sub-pixel wave-front sensing ac‐ curacy is not required. Higher wave-front correction speed should be able to achieve by us‐ ing more CPU cores with a computer. The commercial CPU market for personal computers is being evolved rapidly, with efforts focusing on multi-core CPUs. For example, two Eight-Core Intel Xeon E5-2687W CPUs can be installed in a computer, which will deliver 16 cores in total and each core can run at 3.1GHz clock frequency. In another approach, we are also developing LabVIEW based FPGA technique, which may dramatically increase the running speed of the AO system. The 12x12-actuator DM is also being updated to a 24x24-actuator DM that will have a clear aperture of 9.0 mm, and should deliver better performance. The PSAO is being upgraded accordingly, and we will report our progresses in the near future.
