Van D. Romero

Synthesis of MFI zeolite films on optical fibers for detection of chemical vapors

We report the development of a novel zeolite-incorporated optical fiber sensor and demonstrate its capability for in situ detection of chemical vapors. The sensor comprises a polycrystalline silicalite thin film grown upon the cleaved end face of a standard single-mode optical fiber. The sensor device operates by measuring the optical reflectivity of the zeolite crystals, which changes reversibly in response to the amount of chemical vapor adsorbed in its crystalline microporous structure. The sensor has been successfully demonstrated for measuring the concentration of isopropanol vapor in mixtures with nitrogen gas.

Magdalena Ridge Observatory Interferometer: Status Update

The Magdalena Ridge Observatory Interferometer (MROI) is a ten element optical and near-infrared imaging interferometer being built in the Magdalena mountains west of Socorro, NM at an altitude of 3230 m. The interferometer is being designed and built by a collaboration which includes the New Mexico Institute of Mining and Technology (NMT) as the prime contractor and center for the technical team, and the University of Cambridge, Physics Department at the Cavendish Laboratory, which participates in the design and executes work packages under contract with NMT. This manuscript serves as a status update on MROI, and will present progress and milestones toward the observatorys first fringes in 2008.

The Magdalena Ridge Observatory Interferometer: a fully optimized aperture synthesis array for imaging

The Magdalena Ridge Observatory Interferometer will be the first facility-class optical interferometer optimized strictly for an imaging science mission. The array in its final form is envisaged to comprise ten 1.4 m aperture movable telescopes in a Y configuration, baselines extending from 8 to 400 meters, delay lines capable of tracking well-placed sources for 6 continuous hours, fringe-tracking in the near-infrared , and undertake science observations at both near-infrared and optical wavelengths. The science reference mission includes studies of young stellar objects, a full range of stellar astrophysics, and imaging studies of the nearest and brightest 100 active galactic nuclei. We will be staffing up to our full complement of personnel in New Mexico over the next year. Our goal for first fringes on the first baseline is 2007.

Rotation of a Pulsed Jet, or Plume, in a Rotating Flow: A Source of Helicity for an α-ω Astrophysical Dynamo

A fluid-flow experiment was performed in water to investigate how an expanding pulsed jet rotates when injected off-axis into a rotating annular flow. The pulsed jet simulates a large-scale rising plume in a stellar or accretion disk environment. In the experiment, the pulsed jet was injected parallel to, but radially displaced from, the axis of rotation. The jet was observed to counterrotate Δ ~ π/2 to π rad relative to the rotating frame before dispersing into the background flow. The counterrotation of an expanding pulsed jet in a rotating frame is the key result of the experiment. The counterrotation of the jet occurs because of the increased moment of inertia due to its expansion and conserved angular momentum. Rapid turbulent entrainment of the pulsed jet with the background flow during radial divergence when striking the end wall limits the net rotation of the jet. Shear within the differentially rotating background flow enhances the net rotation of the jet. Naturally occurring buoyant plumes in rotating flows should exhibit this same coherent nature, i.e., the same direction of rotation, the same vertical motion, and the same finite angle of rotation for every plume. This should make pulsed jets, or plumes, when occurring in a conducting medium, nearly ideal for producing helicity for the α-ω dynamo. In the experiment, Couette flow was established in water between two coaxial cylinders with an outer radius R0 = 15 cm, an inner radius R1 = 7.5 cm, and height Z = 10 cm. The Reynolds number of the experiment was Re 105 in order to simulate the behavior of turbulent entrainment at high Reynolds number. The differential rotation of the background flow was varied from constant rotation, dΩ/dR = 0, to Ω ∝ 1/R. The flow was made visible by pulsed hydrogen electrolysis from a tungsten wire and by dispersed guanidine in water. The flow was imaged using a digital video camcorder. These measurements are a precursor to the design and development of an α-ω dynamo experiment using liquid sodium, in turn with the purpose of simulating positive dynamo gain in a naturally occurring astrophysical flow.

The Magdalena Ridge Observatory: a look ahead

The Magdalena Ridge Observatory project has received first- year funding to complete planning and environmental work. The observatory will have three 2.4-meter telescopes that can be used individually for conventional single-telescope projects or linked to do interferometry. The layout of the observatory will allow fixed east-west baselines as long as 75 meters and may include one telescope that can be moved north-south 100 meters or more to improve coverage in the u- v plane.

The Magdalena Ridge Observatory interferometer: first light and deployment of the first telescope on the array

The Magdalena Ridge Observatory Interferometer (MROI) has been under development for almost two decades. Initial funding for the facility started before the year 2000 under the Army and then Navy, and continues today through the Air Force Research Laboratory. With a projected total cost of substantially less than

An optical-fiber-based microsensor for explosives detection

200M, it represents the least expensive way to produce sub-milliarcsecond optical/near-infrared images that the astronomical community could invest in during the modern era, as compared, for instance, to extremely large telescopes or space interferometers. The MROI, when completed, will be comprised of 10 x1.4m diameter telescopes distributed on a Y-shaped array such that it will have access to spatial scales ranging from about 40 milliarcseconds down to less than 0.5 milliarcseconds. While this type of resolution is not unprecedented in the astronomical community, the ability to track fringes on and produce images of complex targets approximately 5 magnitudes fainter than is done today represents a substantial step forward. All this will be accomplished using a variety of approaches detailed in several papers from our team over the years. Together, these two factors, multiple telescopes deployed over very long-baselines coupled with fainter limiting magnitudes, will allow MROI to conduct science on a wide range and statistically meaningful samples of targets. These include pulsating and rapidly rotating stars, mass-loss via accretion and mass-transfer in interacting systems, and the highly-active environments surrounding black holes at the centers of more than 100 external galaxies. This represents a subsample of what is sure to be a tremendous and serendipitous list of science cases as we move ahead into the era of new space telescopes and synoptic surveys. Additional investigations into imaging man-made objects will be undertaken, which are of particular interest to the defense and space-industry communities as more human endeavors are moved into the space environment. In 2016 the first MROI telescope was delivered and deployed at Magdalena Ridge in the maintenance facility. Having undergone initial check-out and fitting the system with optics and a fast tip-tilt system, we eagerly anticipate installing the telescope enclosure in 2018. The telescope and enclosure will be integrated at the facility and moved to the center of the interferometric array by late summer of 2018 with a demonstration of the performance of an entire beamline from telescope to beam combiner table shortly thereafter. At this point, deploying two more telescopes and demonstrating fringe-tracking, bootstrapping and limiting magnitudes for the facility will prove the full promise of MROI. A complete status update of all subsystems follows in the paper, as well as discussions of potential collaborative initiatives.

A new path to first light for the Magdalena Ridge Observatory interferometer

A new type of optical chemical sensor recently developed in our lab has been demonstrated for highly sensitive, in-situ detection of explosives. The sensor is comprised of a dense silica thin film grown on the straight-cut endface of a standard, 125μm telecommunication optical fiber. Silicalite is an all-silica MFI-type zeolite with an effective pore size of 0.55nm. MFI zeolite is highly hydrophobic and selectively adsorbs organics of appropriate molecular size. The sensor device operates through measuring the optical refractive index or optical thickness of the coated zeolite film which changes in response to the adsorption of molecular species in its crystalline structure. In this work, the sensor exhibited different responses to simulants including pxylene, o-xylene, and triisopropylbenzene and trinitrotoluene (TNT) trace vapor in helium carrier gas.

Numerical simulations of MROI imaging of GEO satellites

The Magdalena Ridge Observatory Interferometer (MROI) was the most ambitious infrared interferometric facility conceived of in 2003 when funding began. Today, despite having suffered some financial short-falls, it is still one of the most ambitious interferometric imaging facilities ever designed. With an innovative approach to attaining the original goal of fringe tracking to H = 14th magnitude via completely redesigned mobile telescopes, and a unique approach to the beam train and delay lines, the MROI will be able to image faint and complex objects with milliarcsecond resolutions for a fraction of the cost of giant telescopes or space-based facilities. The design goals of MROI have been optimized for studying stellar astrophysical processes such as mass loss and mass transfer, the formation and evolution of YSOs and their disks, and the environs of nearby AGN. The global needs for Space Situational Awareness (SSA) have moved to the forefront in many communities as Space becomes a more integral part of a national security portfolio. These needs drive imaging capabilities ultimately to a few tens of centimeter resolution at geosynchronous orbits. Any array capable of producing images on faint and complex geosynchronous objects in just a few hours will be outstanding not only as an astrophysical tool, but also for these types of SSA missions. With the recent infusion of new funding from the Air Force Research Lab (AFRL) in Albuquerque, NM, MROI will be able to attain first light, first fringes, and demonstrate bootstrapping with three telescopes by 2020. MROI’s current status along with a sketch of our activities over the coming 5 years will be presented, as well as clear opportunities to collaborate on various aspects of the facility as it comes online. Further funding is actively being sought to accelerate the capability of the array for interferometric imaging on a short time-scale so as to achieve the original goals of this ambitious facility

The MROI's capabilities for imaging geosynchronous satellites

All of the design work and major construction has been completed for the Magdalena Ridge Observatory interferometer (MROI). The majority of the subsystems are currently (2012) being assembled. When completed, the array will consist of 10 fully transportable 1.4 m telescopes. These will support multiple array configurations, with baselines from 7.8 m to 346 m to give sub-milliarcsecond angular resolution. We provide an assessment of the potential imaging capability of the MRO interferometer with regard to geosynchronous targets. Our preliminary results suggest that a significant proportion of GEO targets may be accessible and that it may be possible to routinely extract key satellite diagnostics with an imaging capability that would be able to distinguish, for example, 70 cm features on a 5-meter satellite bus and payload, 30 cm features on a 2-meter satellite bus or similarly sized structure, as well as precise quantitative information on much larger structures such as 10 m long solar panels. Optimised observation and data reduction strategies are likely to allow these limits to be improved in due course.