Design Of Robust Feedback Controllers For A Laser Beam Stabilizer

This work addresses this challenge by employing two different control strategies, namely, Proportional Integral Derivative (PID) and State Feedback with an observer for control

Determination of optical technology experiments for a satellite

Optical technology experiments for satellite - communications, acquisition, tracking, lasers, photometry, and atmospheric

First Results from the CHARA Array. II. A Description of the Instrument

The CHARA Array is a six 1-m telescope optical/IR interferometric array located on Mount Wilson California, designed and built by the Center for High Angular Resolution Astronomy of Georgia State University. In this paper we describe the main elements of the Array hardware and software control systems as well as the data reduction methods currently being used. Our plans for upgrades in the near future are also described

Optical Tracking and Spectral Characterization of Cubesats for Operational Missions

Orbital debris in low Earth orbit is of growing concern to operational satellites from the government and commercial sector. With an uptick in worldwide satellite launches and the growing adoption of the CubeSat standard, the number of small objects in orbit are increasing at a faster pace than ever. As a result, a cascading collision event seems inevitable in the near future. The United States Strategic Command tracks and determines the orbit of resident space objects using a worldwide network of radar and optical sensors. However, in order to better protect space assets, there has been increased interest in not just knowing where a space object is, but what the object is. The optical and spectral characteristics of solar light reflected off of satellites or debris can provide information on the physical state or identity of the object. These same optical signatures can be used for mission support of operational satellite missions- down to satellites as small as CubeSats. Optical observation of CubeSats could provide independent monitoring of spin rate, deployable status, identification of individual CubeSats in a swarm, or possibly attitude information. This thesis first introduces the reader to a review of available observation techniques followed by the basics of observational astronomy relevant to satellite tracking. The thesis then presents the OSCOM system- a system for Optical tracking and Spectral characterization of CubeSats for Operational Missions. OSCOM is a ground-based system capable of observing and characterizing small debris and CubeSats with commercially available optical telescopes and detectors. The system is just as applicable for larger satellites which have higher signal to noise ratio. The OSCOM system has been used to successfully collect time-series photometry of more than 60 unique satellites of all sizes. Selected photometry results are presented along with a discussion of the technical details required for optical observation of small satellites

Integrated photonic transmitters for secure space quantum communication

An important issue in today's information society is the security of data transmission against potential intruders, which always put at risk the confidentiality. Current methods to increase security require that the two parties wishing to transmit information, exchange or share one or more security keys. Once the key has been identified, the information can be transferred in a provable secure way using a one-time pad, i. e. the key length is as long as the plaintext. Therefore, the security of the information transmission is based exclusively on the security of the key exchange. Quantum cryptography, or more precisely quantum key distribution (QKD), guarantees absolutely secure key distribution based on the principles of quantum physics, according to which it is not possible to measure or reproduce a state (e.g. polarization or phase of a photon) without being detected. The key is generated out from the measurement of the information encoded into specific quantum states of a photon, named qubits. For example, a qubit can be created using properties such as the polarization or the phase of a photon. Achieved goals of this thesis are the development of a new class of high speed integrated photonic sources for applications in quantum key distribution systems, capable of producing unprecedented qubit rates (100 Mbps - 1 Gbps) and transmitting those over larger distances than those achieved so far (>200 km). More specifically the work has been focused on developing faint pulse sources which can be used in very demanding environmental conditions, such as those in Space. For the development of these sources, apart from the optical design, essential is the opto-mechanical engineering as well as the integration with the electronics. One of the objectives was to achieve very high level of integration and power efficiency, e.g. volumes and power consumption between 10 and 100 times smaller than those typical of a laboratory experiment. Moreover, work in related parts of a whole QKD transmission system has been carried out. In particular, a new scheme for a compact, fast and simple random number generator has been demonstrated successfully achieving a random number generation rate of 1.1 Gbps. Also, during the course of this thesis, the development and engineering of a free-space QKD optical link has been initiated. This thesis makes use of novel ideas to alternatively demonstrate proof-of-concept experiments, which could then further develop into commercial products. To this end, close collaborations with world-wide leading companies in the field have been established. The Optoelectronics Group at ICFO has been involved in current European Space Agency (ESA) projects to develop a small footprint and low power consumption quantum transceiver and a high-flux entangled photon source.En l’actual societat del coneixement és important la seguretat en la transmissió de dades contra potencial intrusos, els quals sempre posen en risc la confidencialitat. Mètodes actuals per incrementar la seguretat requereixen que les dos parts que volen transmetre informació, intercanviïn o comparteixin una o més claus. Una vegada la clau ha estat identificada, la informació pot ser transferida de forma provadament segura utilitzant ”‘one-time pad”’. Per tant, la seguretat en la transmissió de la informació es basa exclusivament en la seguretat en l’intercanvi de la clau. La criptografia quàntica, o més precisament distribució de clau quàntica (QKD), garanteix absolutament la seguretat de la distribució de la clau basant-se en els principis de la física quàntica, segons la qual no és possible mesurar o reproduir un estat (p. e. la polarització o fase d’un fotó) sense ser detectat. La clau es genera a partir de les mesures de la informació codificada en estat quàntics del fotó, anomenats qubits. Per exemple, un qubit pot ser creat utilitzant propietats com la polarització o fase d’un fotó. Els objectius aconseguits d’aquesta tesis són el desenvolupament d’una nova classe d’emissors fotònics d’alta velocitat per a aplicacions en sistemes de distribució de clau quàntica, capaç¸os de produir velocitats de qubit sense precedents (100 Mbps - 1 Gbps) i transmetre’ls a través de distàncies més llunyanes que les aconseguides fins ara (> 200 Km). Més en concret el treball s’ha centrat en el desenvolupament de fonts de pulsos atenuats que poden ser usades en condicions ambientals molt extremes, com les presents a l’Espai. Per al desenvolupament d’aquestes fonts, apart del disseny òptic, importantíssim es l’enginyeria optomecànica com també la integració amb la electrònica. Un dels objectius ha estat aconseguir un molt alt nivell de integració i eficiència de potència, p. e. volums i consums de potència entre 10 i 100 vegades més petits que els típics en experiments de laboratori. Ademés, s’ha realitzat treball en altres parts relacionades amb un sistema de transmissió QKD. En particular, un nou esquema per a un generador de números aleatori compacte, ràpid i simple ha estat positivament demostrat aconseguint velocitats de generació de números aleatoris de 1:1 Gbps. També, el desenvolupament i enginyeria d’un enllaç òptic per a QKD en espai lliure ha estat iniciat durant aquesta tesis. Aquesta tesis utilitza idees novedoses per a demostrar experiments de prova de concepte, els quals poden esdevenir en productes comercials. Per a aquest fi, s’han establert col•laboracions amb empreses internacionals líders del sector. A més a més, el Grup d’Optoelectrònica de ICFO ha estat involucrat en projectes de la Agència Espacial Europea (ESA) per a desenvolupar un transceptor quàntic de tamany reduït i baix consum de potència, el qual també conté una font de fotons entrellaçts d’alt flux

Mean-Field Stochastic Differential Game for Fine Alignment Control of Cooperative Optical Beam Systems

The deployment of autonomous optical link communication platforms that benefit from mobility and optical data rates is essential in public safety communications. However, maintaining an accurate line-of-sight and perfect tracking between mobile platforms or unmanned aerial vehicles (UAVs) in free-space remains challenging for cooperative optical communication due to the underlying mechanical vibration and accidental shocks. Indeed, a misalignment can result in optical channel disconnection, leading to connectivity loss. To address this challenge, we propose a two-way optical link that coordinates mobile UAVs' closed-loop fine beam tracking operation in a swarm architecture to enhance terrestrial public safety communication systems. We study a dynamic of the optical beam tracking games in which each agent's dynamic and cost function are coupled with the other optical beam transceiver agents' states via a mean-field term. We describe a line-of-sight stochastic cooperative beam tracking communication through a mean field game paradigm that can provide reliable network structure and persistent distributed connectivity and communicability. We derive two optimal mean-field beam tracking control frameworks through decentralized and centralized strategies. The solutions of these strategies are derived from forward-backward ordinary differential equations and rely on the linearity Hamilton-Jacobi-Bellman Fokker-Planck (HJB-FP) equations and stochastic maximum principle. Furthermore, we numerically compute the solution pair to the two joint equations using Newton and fixed point iterations methods to verify the existence and uniqueness of the equilibrium that drives the control to a Nash equilibrium for both differential games

HOLOGRAPHICS: Combining Holograms with Interactive Computer Graphics

Among all imaging techniques that have been invented throughout the last decades, computer graphics is one of the most successful tools today. Many areas in science, entertainment, education, and engineering would be unimaginable without the aid of 2D or 3D computer graphics. The reason for this success story might be its interactivity, which is an important property that is still not provided efficiently by competing technologies – such as holography. While optical holography and digital holography are limited to presenting a non-interactive content, electroholography or computer generated holograms (CGH) facilitate the computer-based generation and display of holograms at interactive rates [2,3,29,30]. Holographic fringes can be computed by either rendering multiple perspective images, then combining them into a stereogram [4], or simulating the optical interference and calculating the interference pattern [5]. Once computed, such a system dynamically visualizes the fringes with a holographic display. Since creating an electrohologram requires processing, transmitting, and storing a massive amount of data, today’s computer technology still sets the limits for electroholography. To overcome some of these performance issues, advanced reduction and compression methods have been developed that create truly interactive electroholograms. Unfortunately, most of these holograms are relatively small, low resolution, and cover only a small color spectrum. However, recent advances in consumer graphics hardware may reveal potential acceleration possibilities that can overcome these limitations [6]. In parallel to the development of computer graphics and despite their non-interactivity, optical and digital holography have created new fields, including interferometry, copy protection, data storage, holographic optical elements, and display holograms. Especially display holography has conquered several application domains. Museum exhibits often use optical holograms because they can present 3D objects with almost no loss in visual quality. In contrast to most stereoscopic or autostereoscopic graphics displays, holographic images can provide all depth cues—perspective, binocular disparity, motion parallax, convergence, and accommodation—and theoretically can be viewed simultaneously from an unlimited number of positions. Displaying artifacts virtually removes the need to build physical replicas of the original objects. In addition, optical holograms can be used to make engineering, medical, dental, archaeological, and other recordings—for teaching, training, experimentation and documentation. Archaeologists, for example, use optical holograms to archive and investigate ancient artifacts [7,8]. Scientists can use hologram copies to perform their research without having access to the original artifacts or settling for inaccurate replicas. Optical holograms can store a massive amount of information on a thin holographic emulsion. This technology can record and reconstruct a 3D scene with almost no loss in quality. Natural color holographic silver halide emulsion with grain sizes of 8nm is today’s state-of-the-art [14]. Today, computer graphics and raster displays offer a megapixel resolution and the interactive rendering of megabytes of data. Optical holograms, however, provide a terapixel resolution and are able to present an information content in the range of terabytes in real-time. Both are dimensions that will not be reached by computer graphics and conventional displays within the next years – even if Moore’s law proves to hold in future. Obviously, one has to make a decision between interactivity and quality when choosing a display technology for a particular application. While some applications require high visual realism and real-time presentation (that cannot be provided by computer graphics), others depend on user interaction (which is not possible with optical and digital holograms). Consequently, holography and computer graphics are being used as tools to solve individual research, engineering, and presentation problems within several domains. Up until today, however, these tools have been applied separately. The intention of the project which is summarized in this chapter is to combine both technologies to create a powerful tool for science, industry and education. This has been referred to as HoloGraphics. Several possibilities have been investigated that allow merging computer generated graphics and holograms [1]. The goal is to combine the advantages of conventional holograms (i.e. extremely high visual quality and realism, support for all depth queues and for multiple observers at no computational cost, space efficiency, etc.) with the advantages of today’s computer graphics capabilities (i.e. interactivity, real-time rendering, simulation and animation, stereoscopic and autostereoscopic presentation, etc.). The results of these investigations are presented in this chapter

Vision technology/algorithms for space robotics applications

The thrust of automation and robotics for space applications has been proposed for increased productivity, improved reliability, increased flexibility, higher safety, and for the performance of automating time-consuming tasks, increasing productivity/performance of crew-accomplished tasks, and performing tasks beyond the capability of the crew. This paper provides a review of efforts currently in progress in the area of robotic vision. Both systems and algorithms are discussed. The evolution of future vision/sensing is projected to include the fusion of multisensors ranging from microwave to optical with multimode capability to include position, attitude, recognition, and motion parameters. The key feature of the overall system design will be small size and weight, fast signal processing, robust algorithms, and accurate parameter determination. These aspects of vision/sensing are also discussed

Publications of the Jet Propulsion Laboratory, 1988

This bibliography describes and indexes by primary author the externally distributed technical reporting, released during calendar year 1988, that resulted from scientific and engineering work performed, or managed, by the Jet Propulsion Laboratory. Three classes of publications are included: JPL publications in which the information is complete for a specific accomplishment; articles from the quarterly Telecommunications and Data Acquisition (TDA) Progress Report; and articles published in the open literature