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We have demonstrated amplitude and phase control at a single wavelength in the near-IR. We are preparing to demonstrate control with our deformable mirror actuator in the near-IR, and in parallel are preparing a demonstration in the mid-IR where the compensator will be required to operate.
We describe the initial setup, configuration, and component level testing procedures that were used to incorporate a Xinetics 349 channel deformable mirror into the DCATT active optical system. Initial flattening results are presented as well as calibration data on actuator gain and mirror response. The RMS measures of surface quality are also analyzed for drift in the power-up state.
Attention is given to experimental results for a binary phase-only filter implementation's correlation operations, using the deformable mirror device (DMD) spatial light modulator as the Fourier plane filter. These results demonstrate the basic capabilities of the DMD in an image correlator system which, in combination with the potential 8-kHz frame rate for 128 x 128 DMDs, can constitute a very high speed pattern recognition system. The DMD has the further capability of operating in the analog mode.
In this paper we describe the complex electric field reconstruction from image plane intensity measurements for high contrast coronagraphic imaging. A deformable mirror (DM) surface is modied with pairs of complementary shapes to create diversity in the image plane of the science camera where the intensity of the light is measured. Along with the Electric Field Conjugation correction algorithm, this estimation method has been used in various high contrast imaging testbeds to achieve the best contrasts to date both in narrow and in broad band light. We present the basic methodology of estimation in easy to follow list of steps, present results from HCIT and raise several open quations we are confronted with using this method.
For the Habitable Worlds Observatory, it is essential to broaden the controllable wavelength bandwidth for high-contrast imaging and spectroscopy to increase the exoEarth yield and characterization. The Parabolic Deformable Mirrors (PDM) under the NASA Headquarters directed ExoSpec Work package is specifically tailored to do so. We have successfully procured a generation 1 (Gen 1) PDM device and completed in-depth characterization of the device. This robust evaluation has become instrumental in informing subsequent stages of development, particularly in shaping the design and specifying requirements for the next generation, Gen2, PDM device. We have built a testbed in an environmentally controlled cleanroom to experimentally demonstrate the use of a parabolic DM in a coronagraph instrument as well an integral field spectrograph (IFS). This versatile testbed is designed to test different DM architectures, various low-order wavefront schemes, and a lenslet based IFS. This provides us with a basis for comparison with different DM configurations – 1) flat DM, 2) parabolic DMs, and 3) a flat DM and parabolic DMs. In this communication, we will discuss the testbed design and updates, parabolic DM characterization, Gen 2 requirement definitions, and different tests planned for the testbed.
For the Habitable Worlds Observatory (HWO), it is essential to broaden the controllable wavelength bandwidth for high-contrast imaging and spectroscopy to increase the exoEarth yield and characterization. The Parabolic Deformable Mirrors (PDM) subpackage, under the NASA Headquarters-directed Exoplanet Spectroscopy (ExoSpec) Work Package, is specifically tailored to do so. We have successfully procured a first-generation (Gen 1) PDM device and completed in-depth characterization of the device. This robust evaluation has become instrumental in informing subsequent stages of development, particularly in shaping the design and specifying requirements for the next generation, Gen 2, PDM device. We have built a testbed in an environmentally controlled cleanroom to experimentally demonstrate the use of a PDM in a coronagraph instrument with an integral field spectrograph (IFS). This versatile testbed is designed to test different DM architectures, low-order wavefront sensing schemes, and a lenslet-based IFS. This provides us with a basis for comparison with different DM configurations: 1) flat DM, 2) PDMs, and 3) a flat DM and PDMs. In this communication, we will discuss the testbed design and updates, PDM characterization, and Gen 2 requirement definitions.
Coronagraph-equipped direct imaging missions need an active wavefront control system to cancel out the optical aberrations that degrade the performance of the coronagraphs. A fast steering mirror is used to control Line-of-Sight (LoS) pointing error caused by the telescope jitter. In addition to controlling other low-order aberrations such as astigmatism and coma, high stroke, high actuator density deformable mirrors (DMs) are also used to control the electric field at the required high spatial frequencies. We are designing a testbed to verify a different deformable architecture, where the powered optic in the optical train are controllable and have lower actuator count compared to the existing DMs with flat nominal surfaces. This simplifies the packaging issue for space missions and reduces both cost and risk of having the entire coronagraph instrument's performance depending on one or two high-actuator count DMs. The testbed would also be capable of testing different low-order wavefront sensing algorithms, which focuses in the near-term on a new adaptive Kalman filtering and gradient decent method to estimate the harmonic LoS errors that affect space telescopes. In long run, we would test different machine learning techniques to estimate low-order aberrations and non-linear algorithms for digging the region of high contrast called the dark holes (DH).
This paper describes adaptive optics control laws that are now being implemented on the Palomar Mountain Hale telescope. This system uses a Shack-Hartman sensor observing natural guide stars to drive a 241 active-actuator deformable mirror and a fast steering mirror.
The MagAO-X instrument is a new extreme adaptive optics system for high-contrast imaging at visibleand near-infrared wavelengths on the Magellan Clay Telescope. A central component of this system is a 2040-actuatormicroelectromechanical deformable mirror (DM) from Boston Micromachines Corp. that operates at 3.63 kHz forhigh-order wavefront control (the tweeter). Two additional DMs from ALPAO perform the low-order (the woofer)and non-common-path science-arm wavefront correction (the NCPC DM). Prior to integration with the instrument, wecharacterized these devices using a Zygo Verifire Interferometer to measure each DM surface. We present the resultsof the characterization effort here, demonstrating the ability to drive tweeter to a flat of 6.9 nm RMS surface (and 0.56nm RMS surface within its control bandwidth), the woofer to 2.2 nm root mean square (RMS) surface, and the NCPCDM to 2.1 nm RMS surface over the MagAO-X beam footprint on each device. Using focus-diversity phase retrievalon the MagAO-X science cameras to estimate the internal instrument wavefront error (WFE), we further show that theintegrated DMs correct the instrument WFE to 18.7 nm RMS, which, combined with a 11.7% pupil amplitude RMS,produces a Strehl ratio of 0.94 at H↵
This paper describes how a micromachined, electrostatically controlled, and capacitively sensed deformable membrane mirror would meet the needs for active and adaptive optical elements.
One of the primary goals of future coronagraph space missions is to spectrally characterize Earth-like exoplanets. Observing efficiency is critical and directly related to how large of a field of view we can correct and the bandwidth of that correction. In addition to the coronagraph itself, the bandwidth and depth of contrast is related to the wavefront control system, which classically uses two deformable mirrors (DMs) in series. The minimum distance between these DMs is determined by the Talbot distance of the beam, meaning it scales as the square of the beam size. NASA Goddard is exploring an alternative design architecture to the two-DM approach in which the reimaging optics for the coronagraph are also deformable and we only retain a high-order pupil DM. With these off-axis parabolic elements being made deformable, the long propagation distance between the two DMs is eliminated. Goddard has procured an off-axis parabolic DM (PDM or OAP DM) from vendor ALPAO, France. A testbed is currently being built to test the PDM and demonstrate its utility for achieving high contrast in a coronagraph. The testbed is also being built with an integrated low-order wavefront sensing capability, allowing for integrated testing of a dynamic environment with multiple estimation and control loops.
By combining the high sensitivity of space telescopes with revolutionary imaging technologies consisting primarily of adaptive optics, the Terrestrial Planet Finder is slated to have imaging power 100 times greater than the Hubble Space Telescope. To this end, Boston Micromachines Corporation, of Cambridge, Massachusetts, received Small Business Innovation Research (SBIR) contracts from the Jet Propulsion Laboratory for space-based adaptive optical technology. The work resulted in a microelectromechanical systems (MEMS) deformable mirror (DM) called the Kilo-DM. The company now offers a full line of MEMS DMs, which are being used in observatories across the world, in laser communication, and microscopy.
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This paper describes a new technique for transferring an entire wafer-level silicon membrane from one substrate to another.