Engineering Papers⌕ Search

Engineering topics

Prada, Camilo Mejia

Publications and source records attributed to Prada, Camilo Mejia.

10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS2021

High Contrast Imaging With MEMS Deformable Mirrors in the Decadal Survey Testbed

Deformable mirrors (DMs) are an essential part of any coronagraphic, high contrast instrument. They mitigate optical aberrations in the system and can even be used to generate contrast for the coronagraph. MEMS DMs from Boston Micromachines have been selected as the baseline for two flagship space telescopes proposed to the 2020 Decadal Survey. Although MEMS DMs have over a decade of heritage on ground-based telescopes and in in-air testbeds around the globe, they have not been tested in vacuum down to the ∼10−10 contrast level needed to image terrestrial exoplanets. In this paper, we describe vacuum tests of MEMS DMs in the Decadal Survey Testbed at the Jet Propulsion Laboratory. The first challenge was a bright, temporally incoherent signal, which was identified as electronics noise and removed with a low-pass filter. After that, the contrast has been limited in broadband light by the strong print-through on the DM surfaces. We performed numerical simulations to confirm that conclusion and to characterize the improvements needed to the MEMS DM surfaces and the testbed layout to attain our goal of 10−10 contrast.

Seo, Byoung-Joon↗
NASA NTRS2021

The Twin Decadal Survey Testbeds in the High Contrast Imaging Testbed facility at NASA’s Jet Propulsion Laboratory

Direct imaging of an Earth-like exoplanet will require future missions, such as the proposed HabEx or LUVOIR concepts, to achieve starlight suppression with planet/star contrast ratios on the order of 10−10 at angular separations <100 milliarcseconds in visible wavelengths. To facilitate the technology and algorithm development required to enable this ambitious scientific goal, NASA’s Exoplanet Exploration Program (ExEP) High Contrast Imaging Testbed (HCIT) facility at the Jet Propulsion Laboratory (JPL) recently commissioned the Decadal Survey Testbed (DST), a state-of-the-art, flexible, and extremely stable coronagraph testbed. This testbed integrates years of experience and lessons learned at HCIT and has now demonstrated contrast ratios as low as few times 10−10 in 10% bandwidth. Following the success of DST, the HCIT team has developed a companion testbed, the Decadal Survey Testbed 2 (DST2) that further implements lessons learned from DST, and will provide the HCIT with additional coronagraph testbed capacity and efficiency. Commissioning for DST2 is currently targeted for Fall 2021. Here we provide an update on the status of DST, and report on the design, performance modeling simulations, and status of integration and testing for DST2, highlighting updates to the design from the original DST.

Siegler, Nick↗
NASA NTRS2021

Enabling High-Contrast Imaging of Binary Stars With the Roman Space Telescope Coronagraph Instrument

A large fraction of Sun-like stars is contained in binary systems, in fact within 10 pc there are 67 FGK stars, out of which 42 belong to a multi-star system, and 28 have companion leak that is greater than 1e-9 contrast, assuming typical Hubble-quality space optics. Currently, those binary stars are not included in the Roman Space Telescope Coronagraph Instrument target list, but they could be observed if high-contrast imaging around binary star systems using Roman was possible. The Multi-Star Wavefront Control (MSWC) algorithm can be used to suppress companion star leakage. If the targets have angular separations larger than the Nyquist controllable region of the Deformable Mirror, MSWC must operate in its Super-Nyquist (SN) mode. This mode requires a target star replica within the SN region in order to provide the ability to null speckles at SN angular separations. For the case of Roman, more than half of the targets that can be observed using MSWC, including Alpha Centauri, have angular separations larger than the Nyquist controllable region of the 48x48 actuator Deformable Mirror (DM) to be used. In this paper, we describe how super-Nyquist MSWC can be implemented in Roman CGI adding a mild grating on a replica of the Wide-field Shaped Pupil mask, which would use a spare space in the Shaped Pupil Active Mechanism. We present the feasibility analysis, simulation results, and discuss the latest results on MSWC experiment from three different laboratories at NASA Ames, the Jet Propulsion Laboratory, and the Subaru telescope.

Prada, Camilo Mejia↗
NASA NTRS2018

WFIRST Low Order Wavefront Sensing and Control Testbed Performance under Flight Like Photon Flux

To maintain the required performance for the WFIRST Coronagraph Instrument (CGI) in a realistic space environment, a Low Order Wavefront Sensing and Control (LOWFS/C) subsystem is necessary. The WFIRST CGI LOWFS/C subsystem would use the Zernike wavefront sensor, which has the phase-shifting disk combined with the coronagraph’s focal plane mask, to sense the low-order wavefront drift and line-of-sight (LoS) error using the rejected starlight. The dynamic tests on JPL’s on the Occulting Mask Coronagraph (OMC) Testbed have demonstrated that LOWFS/C can maintain coronagraph contrast to better than 10-8 in presence of WFIRST-like line of sight and low order wavefront disturbances in both Shaped Pupil Coronagraph (SPC) and Hybrid Lyot Coronagraph (HLC) modes. However, the previous dynamic tests have been done using a bright source with photon flux equivalent to stellar magnitude of Mv = -3.5. The LOWFS/C technology development continues on the OMC testbed especially in evaluating and improving the LOWFS/C performance under the realistic photon flux that is equivalent to WFIRST Coronagraph target stars. Our recent testbed tests have demonstrated that the LOWFS/C can work cohesively with the stellar light suppression wavefront control, which brings broad band coronagraph contrast from 1x10-6 to 6x10-9, while LOWF/C is simultaneously suppressing the WFIRST like LoS and low order wavefront drift disturbances on a source that photon flux is equivalent to a Mv = 2 star. This demonstration mimics the CGI initial dark hole establish process on a bright reference star. We also demonstrated on the testbed that LOWFS/C can maintain the coronagraph contrast by suppressing the WFIRST like line-of-sight disturbances on a fainter Mv = 5 star. This mimics scenario of CGI science target observations. In this paper we will present the recent testbed results on LOWFS/C LoS loops and low order wavefront error correction loop performance on the flight like photon flux.

Truong, Tuan↗
NASA NTRS2018

Hybrid Lyot Coronagraph for WFIRST: High Contrast Testbed Demonstration in Flight-like Low Flux Environment

In order to validate required operation of the proposed Wide-Field InfraRed Survey Telescope (WFIRST) coronagraph instrument, we have built a testbed in Jet Propulsion Laboratory (JPL), which is analogous to the baseline WFIRST coronagraph instrument architecture. Since its birth in 2016, this testbed, named as Occulting Mask Coronagraph (OMC) testbed, has demonstrated several crucial technological milestones: Broadband high contrast demonstration in both Hybrid Lyot Coronagraph (HLC) and Shape Pupil Coronagraph (SPC) modes while the Low Order Wavefront Sensing and Control (LOWFS/C) subsystem senses and corrects the dynamic flight-like wavefront disturbances. In this paper, we present up-to-date progress of HLC mode demonstration in the OMC testbed. While injecting the flight-like low photon flux starlight with expected Line of Sight (LoS) and Wavefront Error (WFE) perturbation to the OMC testbed, we demonstrate generating high contrast dark hole images. We first study the expected photon flux in actual flight environment, and estimate detection noise and estimation accuracy of the complex electric field if the wavefront sensing algorithm is used based on the pair-wise difference imaging. Then, we introduce our improved scheme to mitigate this photon-starved flight-like low flux environment. As a result, we generate a dark hole that meets the WFIRST raw contrast requirements using the 2nd magnitude star light. We establish the key ideas, describe test setups, and demonstrate test results with data analysis.

Wilson, Daniel↗
NASA NTRS2017

Characterization of Low Mass Deformable Mirrors and ASIC Driver for High-Contrast Imaging

The development of compact, high performance Deformable Mirrors (DMs) is one of the most important techno-logical challenges for high-contrast imaging on space missions. Microscale Inc. has fabricated and characterized piezoelectric stack actuator deformable mirrors (PZT-DMs) and Application-Speci c Integrated Circuit (ASIC) drivers for direct integration. The DM-ASIC system is designed to eliminate almost all cables, enabling a very compact optical system with low mass and low power consumption. We report on the optical tests used to evaluate the performance of the DM and ASIC units. We also compare the results to the requirements for space-based high-contrast imaging of exoplanets. .

Prada, Camilo Mejia↗
NASA NTRS2017

Shaped Pupil Coronagraphy for WFIRST: High-Contrast Broadband Testbed Demonstration

The Shaped Pupil Coronagraph (SPC) is one of the two operating modes of the WFIRST (Wide-Field InfraRed Survey Telescope) coronagraph instrument. The SPC provides starlight suppression in a pair of wedge-shaped regions over an 18 percent bandpass, and is well suited for spectroscopy of known exoplanets. To demonstrate this starlight suppression in the presence of expected on-orbit input wavefront disturbances, we have recently built a dynamic testbed at JPL (Jet Propulsion Lab.) analogous to the WFIRST fight instrument architecture, with both Hybrid Lyot Coronagraph (HLC) and SPC architectures and a Low Order Wavefront Sensing and Control (LOWFS/C) subsystem to apply, sense, and correct dynamic wavefront disturbances. We present our best up-to-date results of the static SPC mode demonstration from the testbed, along with model comparisons and performance under realistic dynamical conditions. HLC results will be reported separately.

Cady, Eric↗