Laser Communications ,
Space Hardware ,
Optical Thin Films
Profile Summary
Dr McNally is a seasoned executive, serial entrepreneur, angel investor, inventor, author and Board Director with extensive experience in establishing start-up companies, raising capital, selling companies, leading organizations, managing large programs & penetrating new markets (bio-medical products, laser communications products, airborne & space-based optical systems, ground-based space imaging systems). He has multi-decade experience providing advocacy expertise on Capitol Hill Jim is Treasurer for SPIE, serves as Board Director for TruTouch Technologies, SkyShow and SPIE and Advisory Board for the National Photonics Initiative (NPI). For SPIE, his volunteer service includes the Executive Committee, Strategic Planning, Public Policy, Corporate & Exhibitor, Equity, Diversity & Inclusion Committees, Arthur H. Guenther Congressional Fellow Selection Committee, Financial Advisory, Compensation Committees and CEO Executive Search Committee Jim was part of the 3-person Executive Team that led the sale of ATA to Arlington Capital Partners in 2020. Jim was the founding CEO & Board Chair of TruTouch that developed the world’s 1st non-invasive alcohol measurement product recognized by TIME™ magazine as an Invention of the Year. TruTouch was acquired in 2020. Jim helped establish Lumidigm, Inc., acquired by HID Global in 2014. He was VP Operations at SVS, acquired by Boeing in 2000 He has enjoyed many decades of volunteer work for charities & non-profits including K-8 schools, food banks, senior living facilities, University of New Mexico (UNM) Health Science Center, UNM School of Engineering, UNM Anderson School of Management, the Central New Mexico Community College, & Chair, New Mexico Optics Industry Association Jim received the Distinguished Alumni Award from UNM, Innovate Albuquerque Entrepreneur Small Business Award, Manhattan College Alumni Society Medal & School of Engineering General Excellence Medal. He is co-inventor on five patents and is a Fellow of SPIE
Publications (12)
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Future space-borne synthetic aperture radar, hyper-spectral imaging, and high spatial and temporal resolution imaging will place increasing demands on space network data throughput. It is expected that space data relay systems will require capacities of multiple Terabits per second (Tbps). Free-space optical communication is likely the only technology capable of supporting these data demands. A previous study1 has shown that implementing these high-capacity optical feeder links through a traditional geostationary constellation will pose significant development challenges. Meshed satellite constellations in low earth orbit (LEO), operating at significantly shorter ranges, were shown to have the potential to support Tbps feeder links using the technical capabilities of current free-space optical communication systems. Meshed LEO constellations, however, provide unique challenges, including complex constellation maintenance, dynamic meshing and data routing, and short contact periods with ground stations. We review the design requirements for high capacity LEO relay optical terminals and satellites. The global coverage and ground station downlink opportunities of constellation options are evaluated to develop constellation designs utilizing the minimum number of satellites while providing required feeder link performance. The constellations are designed to provide mesh links with Tbps feeder link capabilities using optical terminals comprised of components within current state-of-the-art and with demonstrated capabilities. These meshed feeder link constellations were then modelled to demonstrate the ability of a LEO constellation to gather Tbps of data over a global network, relay this information around the constellation, and downlink this data to a limited number of ground stations.
Optical space data relay systems will require Terabit per second (Tbps) capacities to match or exceed RF communication capabilities. A previous study1 has shown that implementing these high-capacity optical feeder links through a traditional geostationary constellation will pose significant development challenges. Meshed satellite constellations in low earth orbit (LEO), operating at significantly shorter ranges, were shown to have the potential to support Tbps feeder links using the technical capabilities of current free-space optical communication systems. Meshed LEO constellations, however, provide unique challenges, including complex constellation maintenance, dynamic meshing and data routing, and short contact periods with ground stations. We evaluate constellation geometries and ground station sites to establish minimum system requirements to maintain space-to-ground feeder links for a meshed LEO constellation. System requirements include site diversity and redundancy to compensate for local weather. We examine historical weather data to test the conclusions of the constellation and site diversity evaluation. Simulations of data collection and transfer through meshed LEO constellations and space-to-ground feeder links are performed.
The development of large Low Earth Orbit (LEO) satellite constellations is driving the need for autonomous satellite orbit determination. The present state-of-the art is the use of global positioning system (GPS) receivers on individual satellites that provide the position and time information necessary to determine the satellite orbit. There is a growing realization of potential threats to GPS and Global Navigation Satellite System (GNSS) constellations in general. Loss of GNSS service would have significant implications to these large satellite constellations. At the time of writing, the Galileo GNSS system has been down for a week, and there is very little public information as to why and how long before services will be restored. Free Space Optical Communications (FSOC) between satellites and satellite-to-ground links has the potential to provide an independent source for position and time data necessary for orbit determination. FSOC systems can provide highly accurate ranging and time synchronization between both ends of an FSOC link. In the case of pulse-position-modulation (PPM), commonly used in FSOC systems, precise range and time synchronization is required to make the link work properly. The combination of inter-satellite ranging and ranging to fixed ground stations with access to precise timing can provide significant GPS and GNSS independent autonomous orbit determination of spacecraft and spacecraft constellations.
The continuing need to miniaturize mechanisms with wide range of motion for use in free-space optical communications has motivated the design of a low size, weight, and power (SWaP), two-axis gimbal with an optical fiber wrap as the key enabling feature. Our efforts to design a small gimbal with 100 micro-radian pointing accuracy for free-space optical communications have resulted in an unconventional optical fiber wrap design in order to achieve the low optical noise needed to meet system performance goals. Traditionally, fiber optic leads are installed in a stationary configuration to ensure maximum life and performance for the component. The fiber wrap design employed by Applied Technology Associates utilizes a combination of supplier design specifications and “mechanical spring” design techniques to construct a dynamic, innovative fiber mechanism, with life expectancy scaled to expected on-orbit operations and with negligible performance degradation. An engineering mockup was created to test both life expectancy and polarization performance at accelerated lifetime rates to verify the design. Presented in this paper is the design approach, test configuration approach, resulting lifetime testing (from cyclical stress testing), and polarization performance test outcomes. The polarization performance test outcomes show that the design results exceed planned lifetime goals, and maintain optical performance throughout the testing process. These test results confirm that fiber wrapping is a viable and available tool for miniature mechanisms in compact optical communications gimbals.
The most important single attribute of a Laser Communications Ground Station is the receiver aperture area to maximize the received signal and hence signal-to-noise ratio (SNR). However, the larger the aperture, the greater the negative effects imparted by the atmosphere on the signal, thus causing signal fading and negatively effecting SNR. To mitigate the atmospheric effects of a large aperture, adaptive optics are needed. It has been previously proposed to use a number of smaller telescopes with only simpler tip/tilt correction with non-coherent power combining as a lower cost way to achieve the benefits of a large signal energy capture area without the significantly higher cost of a single large telescope with adaptive optics. This paper will investigate optimal trades of the number and size of individual telescopes to achieve a desired signal capture area of a single large telescope with adaptive optics. The cost of the telescopes, extra beam combining, and especially the atmospheric effects as a function of the size of a telescope with only tip/tilt correction will be addressed.
Given the rapid demand for higher and higher bandwidth and the contention for radio frequency (RF) spectrum allocations, the need for space-based Free Space Optical Communications (FSOC) systems is ever increasing. We have previously presented design concepts for a lightweight, small, and high performance two-axis gimbal focusing on the use of commercial off-the-shelf (COTS) subsystems. Our efforts to design a small gimbal with 100 micro-radian pointing accuracy for FSOC have resulted in an unconventional optical fiber wrap design in order to achieve the low optical noise needed to meet the design goals. However, the design raised concerns about stress induced in the optical fibers. To verify our design assumptions and the actual gimbal performance, a mockup of the fiber wrap configuration was subjected to a Cyclical Stress Test conceived to mimic the desired on-orbit lifetime. At regular intervals throughout the test duration, optical power measurements were collected to characterize the degradation of the fiber wrap fiber. The results of the Cyclic Stress Test validated assumptions regarding the design performance, and provided insights used to modify the design prior to hardware implementation into compact free space optical communications gimbals.
Numerous Free Space Optical Communications (FSOC) applications use fine tracking to achieve precise jitter stabilization necessary for high data rate communications. In addition, precision pointing mechanism are often required for point-ahead of the transmit laser. Prior systems have used either fast steering mirrors (FSMs), piezoelectric fiber optic positioners, or inertially stabilized platforms each of which has its own advantages and disadvantages for different applications.
We developed a small form-factor, high performance FSM capable of meeting both high bandwidth stabilization requirements as well as high precision pointing necessary for the point-ahead function. The current design achieves a 2.5 kHz closed-loop optical track bandwidth, <5 μrad/mrad accuracy, and better than 15 nm rms surface figure error. Because there is no single approach to FSOC architecture, we designed the FSM to be easily scaled and customized for various applications ranging from FSOC, image stabilization, and scanning. Simple choices and customization of the FSM components including the mirror substrate, flexure, feedback sensors, and actuator design can provide custom designs for various applications. Analysis tools were developed to quickly trade the multitude of design parameters that influence performance. This paper reviews the FSM design, performance, and qualification test results, and trade space available to customize the FSM. We present analysis and test data from a couple of design variations to show how our design and analysis approach allows the FSM to be quickly adapted to various performance and environmental requirements.
Numerous Deep Space Optical Communications (DSOC) demonstrations are planned by NASA to provide the basis for future implementation of optical communications links in planetary science missions and eventually manned missions to Mars. There is a need for a simple, robust precision optical stabilization concept for long-range free space optical communications applications suitable for optical apertures and masses larger than the current state of the art. We developed a stabilization concept by exploiting the ultra-low noise and wide bandwidth of ATA-proprietary Magnetohydrodynamic (MHD) angular rate sensors and building on prior practices of flexure-based isolation. We detail a stabilization approach tailored for deep space optical communications, and present an innovative prototype design and test results. Our prototype system provides sub-micro radian stabilization for a deep space optical link such as NASA’s integrated Radio frequency and Optical Communications (iROC) and NASA’s DSOC programs. Initial test results and simulations suggest that >40 dB broadband jitter rejection is possible without placing unrealistic expectations on the control loop bandwidth and flexure isolation frequency. This approach offers a simple, robust method for platform stabilization without requiring a gravity offload apparatus for ground testing or launch locks to survive a typical launch environment. This paper reviews alternative stabilization concepts, their advantages and disadvantages, as well as, their applicability to various optical communications applications. We present results from testing that subjected the prototype system to realistic spacecraft base motion and confirmed predicted sub-micro radian stabilization performance with a realistic 20-cm aperture.
Data transmits via optical communications through fibers at 10’s of Terabits per second. Given the recent rapid explosion for bandwidth and competing demand for radio frequency (RF) spectrum allocations among differing interests, the need for space-based free space optical communications (FSOC) systems is ever increasing. FSOC systems offer advantages of higher data rates, smaller size and weight, narrower beam divergence, and lower power than RF systems. Lightweight, small form factor, and high performance two-axis gimbals are of strong interest for satellite FSOC applications. Small gimbal and optical terminal designs are important for widespread implementation of optical communications systems; in particular, for satellite-to-satellite crosslinks where the advantages of more secure communications links (Lower Probability of Intercept (LPI)/Lower Probability of Detect (LPD)) are very important. We developed design concepts for a small gimbal focusing on the use of commercial off-the-shelf (COTS) subsystems to establish their feasible implementation against the pointing stabilization, size, weight and power (SWaP), and performance challenges. The design drivers for the gimbal were weight, the elevation and azimuth field of regards, the form factor envelope (1U CubeSats), 100 μrad pointing accuracy, and 10 degrees per second slew capability. Innovations required in this development included a continuous fiber passed through an Azimuth Fiber Wrap and Elevation Fiber Wrap, overcoming typical mechanical and stress related limitations encountered with fiber optic cable wraps. In this presentation, we describe the configuration trades and design of such a gimbal.
Along with advantages in higher data rates, spectrum contention, and security, free space optical communications can provide size, weight, and power (SWaP) advantages over radio frequency (RF) systems. SWaP is always an issue in space systems and can be critical in applying free space optical communications to small satellite platforms. The system design of small space-based free space optical terminals with Gbps data rates is addressed. System architectures and requirements are defined to ensure the terminals are capable of acquisition, establishment and maintenance of a free space optical communications link. Design trades, identification of blocking technologies, and performance analyses are used to evaluate the practical limitations to terminal SWaP. Small terminal design concepts are developed to establish their practicality and feasibility. Techniques, such as modulation formats and capacity approaching encoding, are considered to mitigate the disadvantages brought by SWaP limitations, and performance as a function of SWaP is evaluated.
A series of multilayer mirrors was exposed to a high power laser to measure absorption of the coatings and to test for thermal distortion. A high power chemical oxygen iodine laser with a wavelength of 1.315 micrometers was used to irradiate a variety of high reflectivity mirrors. The mirror coatings were multilayers of Ta2O5/SiO2 and Si3N4/SiO2 as well as aluminum enhanced with Nb2O5/SiO2. The dielectric layers were deposited by modulated reactive-dc-magnetron sputtering on fused silica substrates. The coated samples were placed in a vacuum chamber and monitored with a thermal imaging camera and an interferometer during irradiation. Absorption levels as low as 10 ppm were observed and the maximum distortion of the wave front was less than (lambda) /10 at 0.633 micrometers for the best parts.
Thermal optical software has been written and used to reduce surface temperature and optical transmission thermal distortion interferometry data. A high reflectance mirror on a fused silica substrate was irradiated by a high intensity laser beam at 1.3 micrometers . Surface temperature and optical transmission data that anchor the software are presented in this paper. In addition, a novel method of computing the optical transfer function from the interferometer data is discussed.
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