GPI2.0 is an upgrade of the high-contrast instrument known as the Gemini Planet Imager (GPI). This new version is scheduled for installation on Gemini North telescope by the end of 2024. In this document, we outline our approach for addressing Non-Common Path Aberrations (NCPA) measurement and correction within the instrument. Our strategy differs significantly from the methods employed in the original GPI. Our proposal involves the utilization of a dedicated Wavefront Sensor (WFS) positioned within the coronagraph branch to accurately measure NCPAs. Subsequently, we will compensate for these aberrations by transmitting offset signals to the adaptive optics WFS. The chosen dedicated WFS will be a Zernike WFS (ZWFS), known for its exceptional sensitivity. This paper provides insights into the integration plan for incorporating the ZWFS into GPI2.0, details its key characteristics, and outlines the methodology for performing phase inversion based on the ZWFS measurements. Additionally, we present the initial results of experimental tests conducted on the SEAL testbed at the University of California, Santa Cruz (UCSC).
The design of a CubeSat telescope for academic research purposes must balance complicated optical and structural designs with cost to maximize performance in extreme environments. Increasing the CubeSat size (eg. 6U to 12U) will increase the potential optical performance, but the cost will increase in kind. Recent developments in diamond-turning have increased the accessibility of aspheric aluminum mirrors, enabling a cost-effective regime of well-corrected nanosatellite telescopes. We present an all-aluminum versatile CubeSat telescope (VCT) platform that optimizes performance, cost, and schedule at a relatively large 95 mm aperture and 0.4 degree diffraction limited full field of view stablized by MEMS fine-steering modules. This study features a new design tool that permits easy characterization of performance degradation as a function of spacecraft thermal and structural disturbances. We will present details including the trade between on- and off-axis implementations of the VCT, thermal stability requirements and finite-element analysis, and launch survival considerations. The VCT is suitable for a range of CubeSat borne applications, which provides an affordable platform for astronomy, Earth-imaging, and optical communications.
The Hybrid Wave-front Sensor (HyWFS) has previously been developed as a combination of a Pyramid Wave-front Sensor (PyWFS) and a Shack-Hartmann Wave-front Sensor (SHWFS) to capture the desirable properties of each when operated with an unresolved guide beacon. A pyramid prism placed at a focus divides the beacon light into four beams. At a reimaged pupil, a lenslet array creates four separate spot patterns on a detector. The measured intensities may be analyzed both in the manner of a PyWFS and a SHWFS, generating two approximations of the wave front that together achieve the high sensitivity of the PyWFS and the high dynamic range of the SHWFS. Given its inherent sensitivity, calibrating the HyWFS is challenged by the effects of local vibrations and air currents in the laboratory. To overcome this problem, a prototype HyWFS has been built that features a closed loop tip-tilt control sub-system. The design includes additional pupil planes, a Fast Steering Mirror (FSM), and a tip-tilt sensor. The prototype HyWFS will be calibrated with low-order Zernike polynomials at a variety of amplitudes to confirm the sensor’s sensitivity, dynamic range, and the effectiveness of the tip-tilt control loop. The effect of the tip-tilt loop will be quantified by comparing calibration qualities while the loop is active and inactive. The residual wave-front error is anticipated to decrease with active tip-tilt control in both the PyWFS mode and the SHWFS mode. With improved accuracy, the HyWFS is another step closer to on sky operation in a closed loop adaptive optics system.
Recent advances in pointing and tracking capabilities of small satellite platforms have enabled adoption of capabilities such as high-resolution Earth Observation (EO), inter-satellite laser communications and, more recently, quantum communications. Quantum communications requires unusually narrow optical beams and tight pointing performance (on the order of ten microradians) to close an inherently brightness-limited quantum link. This limit is due to quantum communication protocols such as quantum key distribution and teleportation requiring individual quantum states to be transmitted with photon number restrictions. We examine an opportunity to combine quantum communications with laser communications in sharing an optical link. We discuss a combined quantum and laser communication terminal capable of performing space-to-ground entanglement-distribution and high data rate communications on a 12U CubeSat with a 95mm beam expander and an 60 cm aperture optical ground telescope. Photon pairs produced by the quantum terminal are entangled in polarization so the polarization must be maintained throughout the optical link. We discuss active and passive compensation methods in space and polarization reference frame correction using a polarized reference beacon at the ground station. The combined quantum and laser communication terminal approach enables secure communications over an optical channel with rates of 100 Mbps and sub-nanosecond time transfer.
The Coronagraphic Debris Exoplanet Exploring Payload (CDEEP) is a Small-Sat mission concept for high contrast imaging of circumstellar disks. CDEEP is designed to observe disks in scattered light at visible wavelengths at a raw contrast level of 10-7 per resolution element (10-8 with post processing). This exceptional sensitivity will allow the imaging of transport dominated debris disks, quantifying the albedo, composition, and morphology of these low-surface brightness disks. CDEEP combines an off-axis telescope, microelectromechanical systems (MEMS) deformable mirror, and a vector vortex coronagraph (VVC). This system will require rigorous testing and characterization in a space environment. We report on the CDEEP mission concept, and the status of the vacuum-compatible CDEEP prototype testbed currently under development at the University of Arizona, including design development and the results of simulations to estimate performance.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.