Magnetic smart materials (MSMs) offer an alternative to the typical piezo-electric actuators currently used to control X-ray optics on beamlines. MSMs, combined with an overcoating of a magnetic hard material, create a deformable mirror that can operate in a power-off mode. The non-reflective side of the mirror is coated with an MSM and the magnetic hard overcoat. The process works by using an electromagnet (EM) to impose a magnetic field in the bilayer of the MSM and the magnetic hard overcoat, causing the mirror to deflect. Once the EM is turned off, the mirror settles into a new shape within minutes, which can remain intact for days. Since the EM is not fixed to the mirror, the exact placement of the magnetic field can be adjusted by relocating the EM. This feature allows for fine-scale adjustments and avoids the "dead pixel" replacement problem common with piezo patches attached to the mirror. Here, we provide a progress report based on laboratory-produced data.

The sensitivity of infrared (IR) imagers can be significantly improved by reducing the size of photodetectors down to the diffraction limit. Emerging low-dimensional material enable submicron photodetectors, which can be diffraction limited and lead to significant sensitivity improvement in the critical short-wave IR band. However, reaching this limit requires pixel sizes smaller than the metal bumps needed for hybridization to silicon readout chips. Such tiny fragile pixels are susceptible to damages due to the mechanical pressure applied during flip-chip bonding, degrading the number of functional camera pixels. Herein, we systematically characterize the influence of the detector size on the imager pixel yield. We then introduce strategies for improving the yield of sub-micron pixels from less than half of total pixels to more than 3/4 of them. While we used a top-down fabrication for our detectors, the developed method is also applicable to bottom-up fabrication methods to make highly sensitive IR cameras based on emerging low-dimensional material such as catalyst-assisted nanowires.

In a previous paper, we presented the concept of using shape memory alloy sheets as the substrate for normal incidence multi-layer coated mirrors. A shape set sheet has been shown to deploy a figure good to 1 micron. This shape is good enough for a “light bucket.” However, if imaging is desired, then post-deployment corrections can be applied. We provide an update on the improvements we have made to our study. These improvements include ray tracing, polishing, adhesion, and fine (nm) surface adjustments.

Within the framework of investigating the link between central super massive black holes in the core of galaxies and the galaxies themselves, we detected a variable X-ray source in the center of CGCG 077-102 NED02, member of the CGCG 077-102 galaxy pair within the Abell 2063 galaxy cluster. Our goal was then to combine X-ray and optical data to demonstrate that this object harbors an active super massive black hole in its core, and to relate this to the dynamical status of the galaxy pair within the Abell 2063 cluster. We used Chandra and XMM-Newton archival data to derive the X-ray spectral shape and variability. We also obtained optical spectroscopy to detect the expected emission lines that are typically found in Active Galactic Nuclei. And we finally used public ZTF imaging data to investigate the optical variability. There is no evidence of multiple X-ray sources or extended component within CGCG 077-102 NED02. Single X-ray spectral models fit well the source. Non-random significant X-ray flux inter-observation X-ray variabilities were detected, between ~4days for short term variations and up to ~700days for long term variations. Optical spectroscopy points toward a passive galaxy for CGCG 077-102 NED01 and a Seyfert for CGCG 077-102 NED02. We did not detect short-term variability in the optical ZTF light curves. However, we found a significant long-term stochastic variability in the g-band that can be well described by the damped random walk model. Finally, the CGCG 077-102 galaxy pair is deeply embedded within the Abell 2063 potential, and has underwent the cluster influence for a long time. Our observations point toward a moderatly massive black hole in the center of CGCG 077-102 NED02, of ~10^6 Msol. CGCG 077-102 NED02 is not heavily obscured, perhaps due to surrounding intra cluster medium ram pressure stripping.

Magnetic smart materials (MSMs) offer an alternative to the typical piezo-electric actuators that are currently being used to control X-ray optics on beam lines. MSMs combined with an overcoating of a magnetic hard material means a deformable mirror whose non-reflecting side is coated with a MSM plus magnetic hard overcoat can work in a power-off mode. The process works by using an electromagnet (EM) to impose a magnetic field in the bilayer of MSM and magnetic hard overcoat. Once the EM is turned off, the mirror settles to a new shape within minutes. The new shape can then remain intact for days. Since the EM is not fixed to the mirror, the exact placement of the magnetic field can be adjusted by relocating the EM. This feature allows for fine-scale adjustments and avoids the "dead pixel" replacement problem common with piezo patches that are attached to the mirror. We will give an overview and a progress report.

Based on the science case for the SMEX ESCAPE mission, a normal incidence EUV mirror mission would be an interesting follow on. Our provisional SmallSat/CubeSat design has a 1 m diameter primary deployable mirror. The mirror would be coated with multilayers for normal incidence EUV reflectivity. The deployable mirror substrate is a shape memory alloy (SMA). The SMA needs to be over coated with a material that can be polished and then smoothed further. The combination that worked well on an aluminum cylinder is a high phosphorous content electroless nickel (eNiP) super-polished and then coated with carbon nitride (CNx). The multilayers were deposited on the eNiP+CNx stack. We report here our progress toward putting in place the pieces for a proof of concept. We discuss a scale up of previous return to shape on sheets of NiTi and the ray tracing results that demonstrate a sufficient return to shape of 1 micron. Furthermore, corrections post deployment are possible if desired.

The sensitivity of infrared (IR) focal plane arrays (FPAs) is often limited by a low pixel fill factor. Solid immersion microlens arrays address this problem by focusing the light reaching each pixel into the most sensitive part of that pixel. This strategy is used in CMOS image sensors but has not been industrially adopted for IR FPAs due to significant difficulties in integration with compound semiconductors. Here, we present an all-in-one solution for producing solid immersion microlens arrays compatible with various IR FPAs regardless of their substrate material. Our strategy is to use refractive lenses made of SiO2 and Si3N4 with very broad-band and efficient focusing abilities. Notably, our strategy works across a broad range of wavelengths with little performance degradation, meaning it is scalable to various applications. We implemented our method in short-wavelength IR FPAs and demonstrated 7.4 times improvement in quantum efficiency. This is the first demonstration of an immersion microlens array in a non-silicon infrared FPA.

Advances in optical testing are as important as advances in fabrication because one can make only what one can measure. A high-precision metrology capability is utilized to close the gap between interferometric testing and lower precision metrology, laser radar, or contact-probe-based coordinate measuring machines (CMM) to accurately measure surfaces with large form error. This nearly universal optical testing method employs a precision CMM equipped with a non-contact, confocal probe. This technique was developed to characterize and align a broad spectrum of optical surfaces including ones with high slopes that are nearly impossible to measure using traditional interferometric testing without custom-made optics. Optical components covering a wide range of prescriptions, such as large convex conics, high-sloped aspherics, grazing-incidence x-ray optics, and highly deformed flats, were successfully measured. The resulting data were processed using custom-developed routines to determine the optic’s alignment, the departure from design surface, and the as-built prescription parameters. This information was used to verify and guide the development and fabrication of novel optics.

Larger mirrors are needed to satisfy the requirements of the next generation of UV-Vis space telescopes. Our study attempts to meet this requirement by demonstrating a technology that would deploy a large, continuous, high figure accuracy membrane mirror. The figure of the membrane mirror is corrected after deployment using a contiguous coating of a magnetic smart material (MSM) and a magnetic field. The MSM is a magnetostrictive material that is operable by magnetic write head(s), locally imposed on the nonreflective side of the membrane mirror. We report preparation, figure accuracy, stress analysis, and stability of the MSM coated CP1 polyimide substrate membrane minor. The figure accuracy and magnetostrictive performance of the MSM coated membrane mirror are measured; furthermore, stability of the CP1 membrane for 48 h is observed and the results are found to be promising. In addition to membrane coating and the experimental procedure, the results of the surface profiling experiments are introduced and discussed. (C) 2020 Society of Photo-Optical Instrumentation Engineers (SPIE)

Photodetectors with internal gain are of great interest for imaging applications, since internal gain reduces the effective noise of readout electronics. High-gain photodetectors have been demonstrated, but only individually rather than as a full array in a camera. Consequently, there has been little investigation of the interaction between camera complementary metal oxide semiconductor (CMOS) electronics and the slow response time that high-gain photodetectors often exhibit. Here we show that this interaction filters shot noise and causes noise statistics to differ from the common Poisson distribution. As an example, we investigate a 320×256 array of InGaAs/InP high-gain phototransistors bonded to a CMOS readout chip. We demonstrate the filtering effects and discuss their consequences, including new (to the best of our knowledge) methods for extracting gain and increasing dynamic range.

The desirability of making deployable mirrors for space telescopes has been known for years. Yet, once the wave lengths are longer than the short wave radio, progress has been slow. Therefore, we are exploring a new technology based on using a magnetic smart material film deposited on a shape-memory alloy (SMA) sheet. Our preliminary result is that when we apply an about 0.1-0.35 T in-plane magnetic field, we can produce greater than micron deflections in the SMA. Furthermore, we have shown the SMA can return to shape to within 1 micron. We will present an update on how long these deflections can be maintained and our progress toward making the SMA surface smooth enough to produce specular reflection. In addition, we assess the brightness and shininess of the NiTi piece before and after heating that is needed to produce a return to shape.

One of the pressing needs for space ultraviolet-visible astronomy is a design to allow larger mirrors than the James Webb Space Telescope primary. The diameter of the rocket fairing limits the mirror diameter such that all future missions calling for mirrors up to 16 meters in diameter or larger will require a mirror that is deployed post-launch. In response to the deployment requirement, we address the issues of this concept called A Precise Extremely Large Reflective Telescope Using Reconfigurable Elements (APERTURE) with both hardware experiments and software simulations... We designed and built several fixtures with O-rings to hold a membrane. We established a coating process to make a membrane that was coated on one side with Cr and the other side with Cr-Terfenol-D-NiCo. The Terfenol-D (T-D hereafter) is the MSM (Magnetic Smart Memory) we use. We bought and established a procedure for measuring a deformation over time and purchased a Shack Hartmann system from Imagine Optic (https://www.imagine-optic.com). The first substrate we used was DuPont (TM) Kapton® polyimide film. Due to material creep, we found the stability over a 48-hour period with a Kapton substrate was not as good as desired (greater than 1 micron). We then switched to CP1 Polyimide. We found the CP1 much more stable to creep, being stable from about 3 hours to 48 hours to within a measurement error to below approximately 0.1 micron. We produced a 13 micron maximum deviation on a 50-millimeter-diameter piece of CP1 (25 microns thick). The T-D coating was about 2 microns, and the other layers, about 10 nanometers. The magnetic field at the base was about 0.1 teslas. We can make the T-D film at least 5 times thicker and the magnetic field at least 5 times stronger, and hence make deformations as much as 25 times larger. We have a formed a collaboration produced at the NIAC (NASA Innovative Advanced Concepts) mid-term review with Dr. Ron Shiri of Goddard Space Flight Center (GSFC) to explore making controlled deviations on lambda/14-lambda/20 scales which are required to bring a surface to the diffraction limit. We carried out only preliminary work on Si using a Coordinate Measuring Machine (CMM), which produced deviations on the 1 micron level. We are still working on a program to bring to GSFC a flat enough (radius of curvature greater than 10 microns) -coated a Si piece with Cr, T-D, NiCo. Then we plan to carry out tests with an interferometer. Further, we formed a new collaboration with Prof. Rajan Vaidyanathan of the University of Central Florida to replace the CP1 with a shape memory alloy (SMA). With his collaboration, we acquired new Federal funding outside of NASA to explore the use of SMAs (we use NiTi). Our preliminary results indicate that we can produce deformations greater than 1 micron on approximately 100 microns thick. Furthermore we have shown that the NiTi can deploy to better than 1 micron of its set original and then trained shape.

Thin-walled X-ray optics are going to be required to meet the demands of large collecting area versus volume and mass for the next generation X-ray astronomy Flagship Mission. We report here our progress on our concept of meeting the challenge of producing these mirrors. The case we address is the one where the initial fabrication process requires post-fabrication figure correction. Our technology can be applied prior to launch and also enable in-flight figure corrections. Our process is to coat a film of magnetic smart material onto the backside of the thin-walled X-ray mirrors. Then, an electromagnet is used to produce an in-plane stress and thus reshape the mirror. We show in this paper that 500 mu m thick Si wafers can be coated and after coating remains significantly flat, i.e. they have a radius of curvature of about 30 m. We have carried out deflection measurements as a function of the external magnetic field of about 0.1 to 0.3 T and found a nearly linear relationship. We also revisited the stability of induced deflections for up to nearly 70 hours and also demonstrated that the process can produce deflections for fine-scale figure adjustments of order (10 nm) range deflections.

Highly sensitive and fast imaging at short-wavelength infrared (SWIR) is one of the key enabling technologies for the direct-imaging of habitable exoplanets. SWIR imaging systems currently available in the market are dominated by imagers based on InGaAs PIN photodiodes. The sensitivity of these cameras is limited by their read-out noise (RON) level. Sensors with internal gain can suppress the RON and achieve lower noise imaging. In this paper, we demonstrate a SWIR camera based on 3D-engineered InP/InGaAs heterojunction phototransistors with responsivities around 2000 A/W which provides a shot-noise limited imaging sensitivity at a very low light level. We present the details of the semiconductor structure, the microfabrication, and the heterogeneous integration of this camera. The low capacitance pixels of the imager achieve 36 electron effective RON at frame rates around 5 kilo-frames per second at an operating temperature of 220 K and a bias voltage of 1.1 V. This is a significant step toward achieving highly sensitive imaging at SWIR at high frame rates and noncryogenic operating temperatures. Based on the proposed modeling and experimental results, a clear path to reach the RON less than 10 electrons is presented.

The only way to increase the sensitivity of X-ray telescopes without significantly increasing their size (compared to existing telescopes) is to use thinner mirror shells. However, to maintain the figure of thin mirror shells, their shape will need to be adjusted after they are mounted and/or actively controlled during flight. Here we describe progress toward developing a method that can be used to do both. The core of the concept is to coat thin (< 500μm) X-ray mirrors with a ∼ 10μm layer of magnetic smart material (MSM). When an external magnetic field is applied to the MSM layer it will expand or contract, changing the shape of the mirror. We have previously demonstrated that this method can be used to generate a single localized deformation on the surface of a test sample. Here we present work to study how two deformations affect each other. The first deformation that we created has a height of ∼ 5μm. The second deformation, generated by applying a magnetic field to the sample 4mm from the first position, has a height of ∼ 1μm. It is likely that the second deformation is smaller than the first because the two areas where the magnetic field was applied were close to each other. This could have caused the MSM to already be partially expanded in the second area when the field was applied there.

The only way to increase the sensitivity of X-ray telescopes without significantly increasing their size (compared to existing telescopes) is to use thinner mirror shells. However, to maintain the figure of thin mirror shells, their shape will need to be adjusted after they are mounted and/or actively controlled during flight. Here we describe progress toward developing a method that can be used to do both. The core of the concept is to coat thin (<500 μm) X-ray mirrors with a ~10 μm layer of magnetic smart material (MSM). When an external magnetic field is applied to the MSM layer it will expand or contract, changing the shape of the mirror. We have previously demonstrated that this method can be used to generate a single localized deformation on the surface of a test sample. Here we present work to study how two deformations affect each other. The first deformation that we created has a height of ~5 μm. The second deformation, generated by applying a magnetic field to the sample 4 mm from the first position, has a height of ~1 μm. It is likely that the second deformation is smaller than the first because the two areas where the magnetic field was applied were close to each other. This could have caused the MSM to already be partially expanded in the second area when the field was applied there.

We analysed 17 galaxy clusters, and investigated, for the first time, the dependence of the star formation rate (SFR) and specific star formation rate (sSFR) as a function of projected distance (as a proxy for environment) and stellar mass for cluster galaxies in an intermediate-to-high redshift range (0.4 < z < 0.9). We used up to nine flux points (BVRIZYJHKs magnitudes), its errors, and redshifts to compute M-star, SFR, and sSFR through the spectral energy distribution fitting technique. We use a z-dependent sSFR value to distinguish star-forming (SF) from quiescent galaxies. To analyse the SFR and sSFR history we split our sample into two redshift bins: galaxies at 0.4 < z < 0.6 and 0.6 < z < 0.9. We separate the effects of environment and stellar mass on galaxies by comparing the properties of SF and quiescent galaxies at fixed environment (projected radius) and fixed stellar mass. For the selected spectroscopic sample of more than 500 galaxies, the well-known correlation between SFR and M-star is already in place at z similar to 0.9, for both SF and quenched galaxies. Our results are consistent with no evidence that SFR (or sSFR) depends on environment, suggesting that for cluster galaxies at an intermediate-to-high redshift range, mass is the primary characteristic that drives SFR.

In this paper, we report progress to develop adaptive X-ray mirrors using magnetically smart materials or MSM for short. These adaptive X-ray mirrors work using the stress difference a magnetically smart material (MSM) provides under the influence of an external magnetic field. We used silicon substrates coated with Terfenol-D R © (MSM), to act as the actuating layer, and NiCo as our magnetically hard material to retain the surface profile of the mirror after magnetization. Profile measurement of 5mm x 20mm films were done using a Fizcam 2000 interferometer under different conditions. The goal was to show that the samples could be shaped with the help of an external magnetic field, and that the remnant field in the NiCo holds the deflection after the external field has been removed. For this project, we measured three different samples showing a deflection up to 1.34m under 0.12 Tesla; Two of the samples successfully hold some of their deflection under the remnant magnetic field created by the NiCo layer. As a proof of concept, the tests were done with permanent magnetics located on each side of the cantilever. An X-ray beam application would use a electromagnetic/magnetic write head.

We describe our progress in developing a method for correcting residual figure errors in X-ray mirrors. The technology has applications to both synchrotron radiation beamlines and X-ray astronomy. Our concept is to develop mirrors that are on the order of a millimeter thick. A magnetic smart material (MSM) is deposited onto the mirror substrate (silicon) and coated with a magnetically hard material. The shape of the mirror can be controlled by applying an external magnetic field to the mirror. This causes the MSM to expand or contract, thereby applying a magnetostrictive stress to the mirror and changing its shape. The shape change is maintained after the field has been removed by the magnetic hard material, which retains part of the field and prevents the MSM from relaxing. Here we present the results of shaping 200 µm thick silicon (100) 14 × 2 mm cantilevers and 50 × 50 × 0.1 mm substrates. We demonstrate that not only can a sizable deflection be created, but it can also be retained for ∼ 60 hours.

One of the pressing needs for the UV-Vis is an affordable design that allows larger mirrors than the JWST primary. In this publication we report the results of the first year of a NASA Innovative Advanced Concepts Phase II study. Our project is called A Precise Extremely large Reflective Telescope Using Reconfigurable Elements (APERTURE). The concept is to deploy a continuous membrane-like mirror. The mirror figure will be corrected after deployment, causing the figure error to decrease below λ/20. While the basic concept is not new, our innovation lies in a different approach to correcting the residual figure errors from the classical piezoelectricpatch technology. Instead, our concept is based on a contiguous coating of a magnetic smart material (MSM). After deployment, a magnetic write head will move along the non-reflecting side of the mirror. The magnetic field will produce a stress in the MSM which then corrects the mirror shape. This publication summarizes the results of minimizing the MSM deposition stress as well as the size and stability of the deformation, which is maintained by a magnetically hard material.