November 2016: Visible PSF using VAMPIRES camera, wavelngth 625nm.
This sequence shows that although short exposure PSF is diffraction-limited (FWHM~16 mas), jitter smears the long exposure PSF to approximately FWHM=22mas in this sequence (~15 mas jitter). Some low-order instability also visible. Note that the first Airy ring is not symmetric due to residual non-common path error between nearIR and visible.
November 2016: SCExAO and CHARIS in the news.
Please refer to press release by Subaru Telescope and Princeton University for more details, links given below:
Subaru Telescope press release link.
Princeton University press realease link.
Covergarge by local media outlet Hawaii Tribune-Herald link.
September 2016: PSF video
Visible PSF using VAMPIRES camera, wavelngth 725nm.
H-band PSF using Chuckcam
November 2015: Visible Imager funded
SCExAO received a grant for ~US$95k from the Mt Cuba Foundation mainly focused on upgrading the visible imagers into a single ultimate imager. The new imager will use two EMCCDs, a fast liquid crystal switch both of which enable much faster frame rates from the existing polarimetric mode of VAMPIRES. In addition the new imager will for the first time enable spectral differential imaging including the all important H-alpha line amongst many others. A small fraction of the funds will go to developing a post-coronagraphic fiber injection unit for a high-resolution spectrograph.
October 2015: NIR wavefront sensing success
We tested a pyramid wavefront sensor which operates in the NIR both on-sky and in the laboratory. The NIR sensor was based on a Selex SAPHIRA APD array which photon counts in the NIR (H-band). The sensor performed well in initial testing in the laboratory unmodulated. However, because of the limited frame rate of the SAPHIRAs readout electronics, the loop could only be run at 100 Hz, which severely hampered the performance on-sky. The SAPHIRA will receive new read out electronics in the coming months boosting the full frame (320x256) speed from 100 to 800 Hz and even faster with sub-windowing.
Image of the 4 overlapping pupils on the NIR pyramid wavefront sensor (Left) with modulation and (Right) without modulation, taken in the laboratory.
February 2015: More capabilities offered to the community
SCExAO has passed its internal progress review held at the end of January. Both extreme AO and VAMPIRES have been made available for open use from S15B. See current capabilities for full details.
November 2014: Pyramid wavefront sensor success in the laboratory
The new pyramid wavefront sensor underwent significant testing during the November engineering/science run. Significant progress was made throughout the run and in the end the loop was closed on up to 1030 modes (combination of Zernike and Fourier modes) on the internal source with strong turbulence! The internal source was used only because the weather closed in when we got the loop working but nonetheless we demonstrated that starting from an average Strehl of 23% (300 nm RMS wavefront error on turbulence simulator) we could drive the AO corrected Strehl to 95% on average! The figure below shows the Strehl for data cubes before and after the loop was closed on the internal source with turbulence. This is a great milestone and with further upgrades to the software we are confident and on-sky demonstration is not far off. Read more here.
Strehl ratio from internal science camera images while the PyWFS loop was open and closed. The Open loop and Closed loop regime are clearly highlighted. For comparison the typical Strehl ratio achieved by AO188 is also displayed. Data taken in internal source with turbulence.
October 2014: First images with the new pyramid wavefront sensor
Pyramid wavefront sensor rebuilt. This includes the addition of a proper pyramid optic leant to us by Jared Males and Laird Close from MagAO (massive mahalo), the brand new OCAM2K and new control electronics for synchronizing the tip/tilt mirror with the frame acquisition. The first pupil image taken with the new pyramid optic and camera is shown below. The image is very clean and clearly there is little diffraction between the pupils which indicates a high quality pyramid shaped optic. Read more here.
First image of the pupil with the new Pyramid wavefront sensor system.
September 2014: OCAM2k delivered!
OCAM2K has been delivered ahead of time by FIRSTLight Imaging! A massive mahalo to the team for their hard work.
(Left) OCAM 2k delivered to Subaru Telescope.
(Right) OCAM 2k and accessories.
May 2014: Major funding awarded to build an MKID camera
The SCExAO team and collaborators were awarded ~$US1.1M to build an MKIDS detector by the JSPS! This coupled with the $250k awarded by the NAOJ is enough to fund the development of a dedicated 20 pix MKID detector for exoplanet science.
April 2014: Successful observing run
The April observing run was a great success. We revalidated speckle nulling and the LOWFS on-sky with convincing results and VAMPIRES collected a ton of data following its upgrades as well. The icing on the cake was the demonstration of closed loop operation of the high order wavefront sensor (non-modulated pyramid wavefront sensor). With the implementation of 5 GPU's since the December run, we managed to drive the PyWFS at 800 Hz on 200 modes on-sky. We tested the loops performance to cancel aberrations by adding varying static wavefront errors via our deformable mirror on top of the pre-existing aberrations and then watched the restoration of the PSF and the applied volt map post correction. Next steps include adding regularization to prevent actuators in and around the pupil edges from saturating, eliminating existing delays in the loop and applying off-sky response matrices to attempt to get extreme AO correction on the coming June run. Stay tuned! In addition we observed significant improvements in PSF stability as a result of the HiCIAO vibration isolation upgrades. Great success!
March 2014: HiCIAO overhauled to minimize vibrations
The HiCIAO camera was overhauled to include a dual bellows vibration isolation unit. More information can be found on the vibrations page.
The new dual bellows vibration isolation system installed on HiCIAO.
January 2014: Major internal funding awarded for photon-counting cameras
We received funding to purchase two state-of-the-art cameras, namely OCAM 2K and MKIDS. OCAM 2K (FirstLight) is one of the most advanced visible cameras (frame rate of 3.7 kHz with binning, 0.3e- read noise, <0.01e- dark current and very high quantum efficiency between 500 and 900 nm). This camera will be used to replace the Andor Zyla currently used for the non-modulated pyramid wavefront sensor and boost performance significantly. This camera is expected to be delivered in late May 2014 and installed and running a few months after this date. MKIDS stands for Microwave Kinetic Inductance Detector and is a photon counting, energy discriminating superconducting based technology. It is being developed by Prof. Ben Mazin's group at UC Santa Barabara and we are fortunate enough to work with them developing a specific unit for SCExAO. This camera will replace the current high frame rate/speckle nulling camera. With the boost in sensitivity and speed, we will be able to do fast wavefront control and calibration and push speckle nulling and even focal plane wavefront sensing to the limit. MKIDS will take several years to build and test.
(Left) OCAM 2k (Image taken by FirstLight Advanced Imaging).
(Middle) MKIDS detector.
(Right) Prof. Ben Mazin with the entire MKIDS camera assembly (Images taken by Mazin's group at UCSB).