Diffraction in Optical Engineering

<div class="htmlview paragraph">Single cylinder optical engines are used for internal combustion (IC) engine research as they allow for the application of qualitative and quantitative non-intrusive, diagnostic techniques to study in-cylinder flow, mixing, combustion and emissions phenomena. Such experimental data is not only important for the validation of computational models but can also provide a detailed insight into the physical processes occurring in-cylinder which is useful for the further development of new combustion strategies such as gasoline homogeneous charge compression ignition (HCCI) and Diesel low temperature combustion (LTC). In this context, it is therefore important to ensure that the performance of optical engines is comparable to standard all-metal engines. A comparison of optical and all-metal engine combustion and emissions performance was performed within the present study. The objective was to investigate the principal differences between optical and all-metal engines and how these differences ultimately affect mixing, combustion and emissions formation processes. Experimental results reveal the significant impact of differences in heat transfer characteristics between optical and standard engine piston bowls on combustion phasing and engine-out emissions. Quantitative measurements of piston wall temperatures using a laser-induced phosphorescence technique were performed which allowed the subsequent definition of appropriate engine operating strategies so as to compensate for differences in heat transfer properties. Furthermore, differences in combustion chamber geometry were also studied. Geometrical differences can arise as a result of dynamic (compressive/tensile) and thermal loading of the extended piston-liner assembly on the optical engine, potentially leading to changes in the effective compression ratio. In addition, intake charge dilution in optical engines is often achieved via the use of simulated exhaust gas recirculation (EGR). A comparison has been made between simulated EGR (using pure nitrogen) with real EGR under Diesel LTC conditions. Finally, ‘pure’, single component fuels are often employed in optical Diesel engines due to laser diagnostic constraints. However these fuels generally differ from standard Diesel fuel in terms of cetane number and fuel volatility which can significantly influence the combustion and emissions characteristics in optical engines. These aspects are discussed within the present study.</div> <div class="htmlview paragraph">An improved understanding of the differences between optical and all-metal engines has allowed us to develop appropriate strategies to compensate for these differences on the optical engine. It is shown here that combustion phasing (and engine-out emissions) matching between optical and all-metal engines can be achieved even for advanced LTC Diesel combustion strategies. The ability to ensure fully representative combustion and emissions behaviour of optical engines ultimately increases the value of optical engine data, highlighting the importance of using such engines as research tools for the further development of innovative, low emission combustion concepts.</div>

Single cylinder optical engines are used for Internal Combustion (IC) engine research as they allow for the application of qualitative and quantitative non-intrusive, diagnostic techniques to study in-cylinder flow, mixing, combustion and emissions phenomena. Such experimental data is not only important for the validation of computational models but can also provide a detailed insight into the physical processes occurring in-cylinder which is useful for the further development of new combustion strategies such as gasoline Homogeneous Charge Compression Ignition (HCCI) and Diesel Low Temperature Combustion (LTC). In this context, it is therefore important to ensure that the performance of optical engines is comparable to standard all-metal engines. A comparison of optical and all-metal engine combustion and emissions performance was performed within the present study. The objective was to investigate the principal differences between optical and all-metal engines and understand how these differences ultimately affect mixing, combustion and emissions formation processes. Experimental results reveal the significant impact of differences in combustion chamber wall temperatures between optical and standard engine piston bowls on combustion phasing and engine-out emissions. Quantitative measurements of piston wall temperatures using a laser-induced phosphorescence technique were performed which allowed the subsequent definition of appropriate engine operating strategies so as to compensate for differences in heat transfer properties. Furthermore, differences in combustion chamber geometry were also studied. Geometrical differences can arise as a result of dynamic (compressive/tensile) and thermal loading of the extended piston-liner assembly on the optical engine, potentially leading to changes in the effective Compression Ratio. In addition, intake charge dilution in optical engines is often achieved via the use of simulated Exhaust Gas Recirculation (EGR). A comparison has been made between simulated EGR (using pure nitrogen) with real EGR under Diesel LTC conditions. Finally, “pure”, single component fuels are often employed in optical Diesel engines due to laser diagnostic constraints. However, these fuels generally differ from standard Diesel fuel in terms of cetane number and fuel volatility which can significantly influence the combustion and emissions characteristics in optical engines. These aspects have also been investigated within the present study.An improved understanding of the differences between optical and all-metal engines has allowed us to develop appropriate strategies to compensate for these differences on the optical engine. It is shown here that combustion phasing (and engine-out emissions) matching between optical and all-metal engines can be achieved even for advanced LTC Diesel combustion strategies. The ability to ensure fully representative combustion and emissions behaviour of optical engines ultimately increases the value of optical engine data, highlighting the importance of using such engines as research tools for the further development of innovative, low emission combustion concepts.

The expansion in the fields of optical engineering and optoelectronics has made it essential to introduce optical engineering concepts into undergraduate courses and curricula. Because of limits on the number of course requirements for the B.S. degree, it is not clear how these topics should be introduced without replacing some of the traditional requirements. This paper demonstrates how optical engineering concepts can be easily presented as an integral part of electrical engineering subjects, with a minimal amount of replacement, while enhancing the depth and understanding of both fields. Courses such as linear signals and systems, electricity and magnetism, and electronics which traditionally represent the core requirements of the undergraduate electrical engineering curriculum contain subjects that have direct correlations with optical engineering concepts. The major changes that are needed are the creation of textbooks that contain concepts and examples in areas of both optical and electrical engineering and some relearning and familiarization on the part of instructors. This approach allows for a fresh look at courses being offered in electrical engineering, while providing the necessary background in optical engineering for students.

Globalization and diversification of education in optical engineering causes a number of new phenomena in students' learning paths. Many students have an interest to get some courses in other universities, to study in international environment, to broaden not only professional skills but social links and see the sights as well etc. Participation in short educational programs (e.g. summer / winter schools, camps etc.) allows students from different universities to learn specific issues in their or in some neighbor field and also earn some ECTS for the transcript of records. ITMO University provides a variety of short educational programs in optical design and engineering oriented for different background level, such are: Introduction into optical engineering, Introduction into applied and computer optics, Optical system design, Image modeling and processing, Design of optical devices and components. Depending on students' educational background these programs are revised and adopted each time. Usually the short educational programs last 4 weeks and provide 4 ECTS. The short programs utilize a set of out-of date educational technologies like problem-based learning, case-study and distance-learning and evaluation. Practically, these technologies provide flexibility of the educational process and intensive growth of the learning outcomes. Students are satisfied with these programs very much. In their feedbacks they point a high level of practical significance, experienced teaching staff, scholarship program, excellent educational environment, as well as interesting social program and organizational support.

Optical technologies are promising candidates to improve or even revolutionize future Global Navigation Satellite Systems (GNSS). The advantages of optical technologies compared to their classical microwave counterparts are numerous, e.g. better frequency stabilities of optical clocks or higher ranging accuracy using optical links. There are already studies of new concepts for GNSS, architectures which almost completely rely on optical technologies. The most prominent and promising idea is DLR’s Kepler architecture concept, which is based on optical frequency references (OFRs) as well as on bi-directional laser communication and ranging terminals (LCRTs). Compact, highly stable, laser-optical clocks, established by combining optical frequency references with optical frequency combs, will significantly improve future generations GNSSs, such as the European Galileo system. When combined with optical laser links, e.g. via LCRTs, to ground infrastructure and between GNSS satellites, they will result in a higher accuracy of position determination on Earth. At the same time, it will be possible to reduce the complexity and size of GNSS ground infrastructure. In order to initiate the revolution of GNSS DLR prepares an in-orbit verification mission on the Airbus Bartolomeo platform which is attached to the Columbus module of the International Space Station (ISS). The platform can accommodate up to twelve external payloads and offers a unique opportunity for demonstration and verification missions in space, especially as the operational concept includes the return of payloads at the end of their mission period. The primary objective of COMPASSO is to prove the feasibility of in-orbit operation of optical key technologies as well as to pave the way for long duration (10 to 15 years) operation of laser-optical technology, in future generations of the Galileo system and in scientific space missions, e.g. within the Next Generation Gravity Mission (NGGM) program, or the Laser Interferometer Space Antenna (LISA). The project started in 2020 and the envisaged launch is 2025. COMPASSO can be roughly divided into three phases: 1) Payload development and launch: during this phase, the individual payload subsystems will be developed, tested, and integrated onto the Bartolomeo ArgUS Multi-Payload Carrier. A period of about four years is planned for this phase. 2) Experimental phase on the ISS: the planned mission experiments will be performed during this phase. It will last about 18 months. 3) Return and validation: in this phase, the mission will be concluded, and the subsystems will be dismantled, returned to Earth and handed over to DLR for tests and evaluation. The payload of the mission comprises several optical key technologies, i.e. two absolute optical frequency reference systems based on molecular iodine, one optical frequency comb (OFC) and one bi-directional laser communication and ranging terminal. A positioning, velocity, attitude and time (PVAT) system as well as an on-board computing and data storage system completes the core elements of the overall payload. COMPASSO’s optical frequency references are based on Doppler-free spectroscopy of molecular iodine. Both references are using lasers operating at 1064nm which can be stabilized on the same or on different (nearby) hyperfine transitions of molecular iodine near a wavelength of 532nm. An optical frequency comb operating at 1550nm center wavelength with a repetition rate of 100MHz transfers the frequency stability of the two references from the optical to the radio frequency domain. In addition, the frequency comb can be referenced to an on-board microwave reference consisting of a high-performance GNSS disciplined crystal oscillator (OCXO), thereby allowing multiple comparative measurements to assess the frequency stability in different frequency regimes and in the relevant time periods of the references/clocks. A bi-directional LCRT operating at 1064nm enables time and frequency transmission between the stable clock signals on the ISS and on Earth – together with clock synchronization, high-precision ranging (distance measurement) and data communications. By comparing the absolute frequency of the iodine reference operated in orbit with the corresponding value on ground, an analysis of the gravitational red shift can be used as a test of the general theory of relativity. The core components listed above will form the COMPASSO payload once they are integrated and installed on the Bartolomeo ArgUS Multi-Payload Carrier. The physical data connection will be provided via a General-purpose Oceaneering Latching Device 2 (GOLD-2) connector, the standard interface for all Bartolomeo payloads. The payload will be launched pressurized onboard an ISS visiting vehicle, transferred to the outside through the Bishop airlock and installed with the ISS robotic manipulator system. COMPASSO will be operated by the DLR German Space Operations Center supported by the European Space Agency Columbus Control Center and the Airbus Bartolomeo Control Center using the ISS ground segment infrastructure.

In 1929, a grant from Eastman Kodak and Bausch and Lomb established The Institute of Optics as the nation's first academic institution devoted to training optical scientists and engineers. The mission was 'to study light in all its phases', and the curriculum was designed to educate students in the fundamentals of optical science and build essential skills in applied optics and optical engineering. Indeed, our historic strength has been a balance between optical science and engineering--we have alumni who are carrying out prize-winning research in optical physics, alumni who are innovative optical engineers, and still other alumni who are leaders in the business community. Faculty who are top-notch optical engineers are an important resource to optical physics research groups -- likewise, teaching and modeling excellent optical science provides a strong underpinning for students on the applied/engineering end of the spectrum. This model -an undergraduate and graduate program that balances fundamental optics, applied optics, and optical engineering- has served us well. The impressive and diverse range of opportunities for our BS graduates has withstood economic cycles, and the students graduate with a healthy dose of practical experience. Undergraduate advisors, with considerable initiative from the program coordinator, are very aggressive in pointing students toward summer research and engineering opportunities. The vast majority of our undergraduate students graduate with at least one summer of experience in a company or a research laboratory. For example, 95% of the class of 2008 spent the summer of 2007 at companies and/or research laboratories: These include Zygo, NRL, Bausch and Lomb, The University of Rochester(The Institute of Optics, Medical Center, and Laboratory for Laser Energetics), QED, ARL Night Vision laboratories, JPL, Kollsman, OptiMax, Northrup Grumman, and at least two other companies. It is an impressive list, and bodes well for the career preparation for these students. While this extracurricular experience is truly world-class, an integrated design experience defined within our academic program is increasingly necessary for those going on to professional careers in engineering. This paper describes the philosophy behind a revision to our undergraduate curriculum that integrates a design experience and describes the engineering laboratory that has been established to make it a reality. The laboratory and design center has been named in honor of Robert E. Hopkins, former director and professor, co-founder of Tropel corporation, and a lifelong devotee to engineering innovation.

Hilda Gertrude Kingslake/Rudolf Kingslake

Nowadays reducing green-house gas emissions and pushing the fossil fuel savings in the field of light-duty vehicles is compulsory to slow down climate change. To this aim, the use of new combustion modes and dilution strategies to increase the stability of operations rich in diluent is an effective technique to reduce combustion temperatures and heat losses in throttled operations. Since the combustion behavior in those solutions highly differs from that of typical market systems, fundamental analyses in optical engines are mandatory in order to gain a deep understanding of those and to tune new models for improving the mutual support between experiments and simulations. However, it is known that optical accessible engines suffer from significant blow-by collateral flow due to the installation of the optical measure line. Thus, a reliable custom blow-by model capable of being integrated with both mono-dimensional and three-dimensional simulations was developed and validated against experimental data. The model can work for two different configurations: (a) stand-alone, aiming at providing macroscopic data on the ignitable mixture mass loss/recover through the piston rings; (b) combined, in which it is integrated in CFD engine simulations for the local analysis of likely collateral heat release induced by blow-by. Furthermore, once the model was validated, the effect of the engine speed and charge dilution on the blow-by phenomenon in the optical engine were simulated and discussed in the stand-alone mode.

Faculty members from three departments at North Dakota State University (Physics, Electrical and Computer Engineering, and Chemistry) have cooperated to develop a joint program in optical science and engineering. An option in Optical Engineering has been established within the major in electrical engineering and an option in Optical Science and Engineering has been established within the major in physics. A core course, Optics for Scientists and Engineers, was introduced in Fall Semester, 2001 and is being offered again in 2002. This new course provides students with the fundamentals necessary to enable them to successfully apply optics in their respective majors. Students learn applied optics through a sequence of multidisciplinary laboratory experiences. This course was adapted from a similar course in the Optical Science and Engineering Program, New Jersey Institute of Technology. During Fall Semester 2001, seventeen students successfully completed the course. Interest in the course offering in the fall of 2002 is high. In general the course has awakened an interest in optics among engineering and science majors.

At the present of the 21st century, optical technology became what must be in our life. If there is no optical technology, we cannot use optical equipments such as the camera, microscopes, DVD, LEDs and laser diodes (LDs). Optics is also the leading part in the most advanced scientific field. It is clear that the organization which does education and research is required in such a very important area. Unfortunately, there was no such organization in Japan. The education and research of light have been individually done in various faculties of universities, various research institutes, and many companies. However, our country is now placed in severer surroundings, such as the globalization of our living, the accelerated competition in research and development. This is one of the reasons why Utsunomiya has established for Optical Research and Education (CORE) in 2007. To contribute to optical technology and further development of optical industry, Center for Optical Research and Education (CORE), Utsunomiya University promotes education and research in the field of the optical science and technology cooperatively with industry, academia and the government. Currently, 6 full professors, 21 cooperative professors, 2 visiting professors and 7 post-doctoral researchers and about 40 students are joined with CORE. Many research projects with industries, the local government of Tochigi as well as Japanese government. Optical Innovation has established in CORE by supporting of Japan Science and Technology Agency in 2011 to develop advanced optical technologies for local companies.

Future generations of global navigation satellite systems (GNSSs) can benefit from optical technologies. Especially optical clocks could back-up or replace the currently used microwave clocks, having the potential to improve GNSS position determination enabled by their lower frequency instabilities. Furthermore, optical clock technologies—in combination with optical inter-satellite links—enable new GNSS architectures, e.g., by synchronization of distant optical frequency references within the constellation using time and frequency transfer techniques. Optical frequency references based on Doppler-free spectroscopy of molecular iodine are seen as a promising candidate for a future GNSS optical clock. Compact and ruggedized setups have been developed, showing frequency instabilities at the 10–15 level for averaging times between 1 s and 10,000 s. We introduce optical clock technologies for applications in future GNSS and present the current status of our developments of iodine-based optical frequency references.

The design of a computing machine takes place at several levels of abstraction ranging from materials and device engineering to system architecture to high-level software. This system of levels of abstraction enables the design problem to be broken down into manageable subproblems, much as in a procedural programming language. On the other hand, it makes difficult the introduction of novel concepts and technologies such as optoelectronic device planes (“smart pixels”), which do not readily fit in the existing scheme of things. We try to develop an understanding of this system of levels of abstraction, why and how it resists the introduction of optical technology, and how one can modify it so as to successfully house optical technology. We argue that in the near future, optoelectronic technology can be successfully introduced if: (i) changing technology or applications create a significant bottleneck in the existing system of levels of abstraction that can be removed by the introduction of optical technology (e.g. interconnections, memory access); (ii) special purpose applications involving very few levels of abstraction can be identified (e.g. sensing, image processing); (iii) it is possible to modify a few levels of abstraction above the level that optical technology is introduced, so that the optical technology is smoothly “grafted” to the existing system of levels of abstraction (e.g. modifying communications schemes or standards so as to match the capabilities of optical switching systems, employing parallel architectures to match the parallel flow of information generated by optical subsystems).KeywordsCellular AutomatonOptical TechnologyOptical MemorySwitching NetworkOptical InterconnectionThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

ESA's Telecommunications and Integrated Applications Directorate (TIA) has launched a new ARTES programme element dedicated to Optical Communication Technologies, called ScyLight (SeCure and Laser communication Technology, pronounced “skylight”). ScyLight supports the development and deployment of innovative optical technologies for satellite communication as well as assist industry in developing new market opportunities for optical communication technologies. The commercial take-up of optical technologies is believed to be the next breakthrough in the Satcom market arena, addressing the need for the ever-increasing data rate and secure communication. Today's developments and early implementations cannot demonstrate the full capabilities of the optical communication technology, as the individual solutions are mainly embarked in non-optimized systems, focusing on one particular area only (e.g. high data rate transmission from one point to another). Although the strong position of the European and Canadian Industry has been demonstrated, the technology gap is still large lacking its proof in-orbit for the commercial use of optical applications. The programme will concentrate European and Canadian efforts on optical communication technologies in the following areas: •Optical Communication Technology at System Level •Optical Communication Terminal Technology •Intra-Satellite Photonics/Optical Payloads •Quantum Cryptography Technologies in Space and initial services demonstration The paper will give an overview of the ScyLight framework and inform about some of the activities planned under the new ARTES framework ScyLight.

Optical communication technologies offer unprecedented transmission data rates, resilience and data security to satellite communications. ESA and its member states have successfully introduced optical communication technologies in the European Data Relay System (EDRS), providing commercial Quasi-Real-Time-Data service to the European Commission Copernicus satellite fleet (Sentinel-1A/B, Sentinels-2A/B). The EDRS / SpaceDataHighway has already provided more than 25.000 successful links since start of operations in 2016, resulting in an availability of >99.5%, [1], [2]. Nonetheless, full capabilities of optical technologies cannot be fully exploited, because these optical are mainly used in non-optimized SatCom systems. In response, a dedicated programme for Optical Communication Technologies was created in 2016 by ESA called ScyLight (SeCure and Laser communication Technology). Furthermore, to address the system level aspects for the massive introduction of optical / photonic technologies in SatCom systems, ESA has recently launched several internal and external initiatives in preparation of an innovative project proposal called HydRON (High Throughput Optical Network), [3]. In HydRON, optical interconnections in the Tbps regime (Terabit per second) are envisaged including All-Optical payloads furnishing the bridges for a truly Fibre in Space network, as shown in Figure 5. Technically speaking HydRON aims at Tbps All-Optical Network solutions, dividing the satellite payload into (i) a network part and (ii) an application / service part, equivalent to the backbone part and the access part of optical fibre networks on ground. The application / service part (i.e., the RF payload) has access to the network part (i.e., the HydRON elements), in a similar way as computers are connected to the terrestrial network. HydRON will prepare optical feeder links into a network of in-orbit Technology Demonstrators (called HydRON#1, #2, etc.), which will be interconnected by means of Tbps laser intersatellite links. WDM (W avelength Division Multiplexing) laser communication terminals (on ground and in space), and optical switching / routing capabilities on-board the network nodes in space will be implemented together with optical to enable a high throughput network connection to the application / service part (i.e., the RF payload). The space network concept will reduce the dependency on single ground stations as all HydRON nodes will get their particular data via the network they are interfacing with. A combination of new optical technologies, novel photonics equipment and efficient network concepts will be proven in orbit. However, the overall network architecture must be optimized for satellite networks. This architecture must be satellite-technology specific and adaptable to the changing network conditions. The ultimate goal is to seamlessly integrate the space optical transport network into the terrestrial high capacity network infrastructure: the Fibre in the Sky.

This paper analyses the evolution of courses in the Institute of Technology Carlow (formerly the Regional Technical College) in physics, optics, photonics, instrumentation and optoelectronics from 1979. Notably, these course developments culminated in the fist specialist optoelectronic Honours degree in the UK or Ireland, which ran with outstanding success for over a decade under the umbrella of the University of Essex. In the last year, the first specialist degree in Optical Engineering to appear perhaps indeed in Europe has been launched. All these development of Irish optics education have been achieved against unresponsive national and institutional policies framed by a severe reluctantly to accept the need for technical manpower outside of the established disciplines. Other associated optical course innovations of the 'Computer Networking and Optical Communications' National Certificate/Diploma and then subsequently 'Networking' degree course have developed in Carlow exclusively on the basis of the photonics diploma material and contain large element of optical fiber telecommunications/photonics material. The exciting Carlow odyssey is however just beginning as can be seen by the preparation of a further new degree in Optical Engineering Design. This course it is hoped will comprehensively address the issues of training manpower for optical device and system engineering.