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Conference on current developments in Lens design and optical Systems engineering

作者： Brunello, P Peron, F Barbieri, C Fornasier, S IUAV Univ Dept Bldg Construct Venice Italy

ISBN: (纸本)0819437387

After the experience of GIOTTO fly-by to comet Halley in 1986, the European Space Agency planned to improve the scientific knowledge of these astronomical objects by means of an even more ambitious rendezvous mission with another comet (P/Wirtanen). This mission, named ROSETTA, will go on from 2003 to 2013, ending after the comet perihelion phase and including also the ny-by with two asteroids of the main belt (140 Siwa and 4979 Otawara). Scientific priority of the mission is the in situ investigation of the cometary nucleus, with the aim of better understanding the formation and the composition of planetesimals and their evolution over the last 4.5 billions of years. In this context, the Authors were involved in the design of the baffling for the Wide Angle Camera (WAC) of the imaging system (OSIRIS) carried on board of the spacecraft. Scientific requirements for the WAC are: a large field of view (FOV) of 12 degrees x 12 degrees with a resolution of 100 mu rad per pixel, UV response, and a contrast ratio of 10(-4) in order to detect gaseous and dusty features close to the nucleus of the comet. To achieve these performances, a fairly novel class of optical solutions employing off-axis sections of concentric mirrors was explored. Regarding baffling, the peculiar demand was the rejection of stray-light generated by the optics for sources within the FOV, since the optical entrance aperture is located at the level of the secondary mirror (instead of the primary as usual). This paper describes the baffle design and analyzes its performances, calculated by numerical simulation with ray tracing methods, at different angles of incidence of the Light, for sources both outside and inside the field of view.

关键词： baffling system optical design stray-light analysis

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Reflectivities of light-absorptive coatings within visible wavelengths range

Reflectivities of light-absorptive coatings within visible w...

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Conference on current developments in Lens design and optical Systems engineering

作者： Moldosanov, KA Henneck, R Skrynnikov, AM Kashirin, VA Makarov, VP Kobtsov, GA Samsonov, MA Kim, LS Special Design Off OKB Aalam Bishkek 720021 Kyrgyzstan

ISBN: (纸本)0819437387

This paper concerns the light-absorptive coatings intended for reduction of stray sunlight in the satellite-borne optical instrumentation and particle-analyzing apparatus operating in open space under intensive solar illumination. Though the inner surfaces are the passive elements in optical instruments, nontheless the condition and reflectivity of their surfaces can have noticeable effect on the signal-to-noise ratio of their detectors. In order to reduce an influence of the stray light on sensitivity of devices, the reflectivities of inner surfaces are strived to keep minimum in those wavelengths ranges, where the detectors spectral responses are high. We measured reflectivities of several types of traditional Tight-absorptive coatings and also tested our own approach to development of low reflectivity materials. The reflectivities were measured in visible and near-infrared wavelengths ranges (400 to 927 nm), as well as at the hydrogen Lyman-alpha line (121.6 mn), the most intensive line of the solar UV radiation. Also, the values of the solar absorptance alpha (s) and the emissivity epsilon were measured. They made it possible to classify the investigated coatings with their respects to a possible use in converters of solar radiation into the heat. Conclusions are given on application of diverse coatings depending on the instrument's detector type, operational wavelengths range, and operating conditions.

关键词： stray light sunlight light-absorptive coating low reflectivity material optical instrumentation

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Optimum design of a lightweight mirror using aluminum foam or honeycomb sandwich construction - A case study for the GLAS telescope

Optimum design of a lightweight mirror using aluminum foam o...

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Conference on current developments in Lens design and optical Systems engineering

作者： Conkey, SB Lee, C Chaykovsky, S Content, D Morell, A Budinoff, J Swales Aerosp Inc Beltsville MD 20705 USA

ISBN: (纸本)0819437387

A simple closed form solution was derived for the optimum weight design of a cylindrical sandwich mirror for a given self-weight deflection and mirror radius. This optimum solution is based on the generalized deflection equation for an axisymmetrically supported thick circular plate. This two parameter equation of deflection captures the deflection of the plate caused by bending and transverse shear. The solution yields the optimum facesheet thickness, core thickness, and core density. The derived optimum solution was used in a case study for the GLAS (Geoscience Laser Altimeter System) primary mirror. This Beryllium mirror is manufactured with an open back isogrid pattern. The objective of this study is to determine a lightweight mirror design using Aluminum sandwich construction that can meet the performances of the current mirror and reduce fabrication costs. With the optimum solution several first order approximations using Aluminum honeycomb or foam core were determined. The performance, 1 g deflection, and wave front error of these designs was determined from Finite Element Analysis. The results conclude that sandwich construction outperforms the isogrid design by significant margins on both weight and distortion if the same material is used. Because of its superior specific stiffness the Beryllium isogrid design still marginally outperforms the optimum Aluminum sandwich design. However, the Aluminum sandwich design should provide significant advantages on cost and ease of fabrication over Beryllium isogrid designs.

关键词： aluminum foam lightweight sandwich panel mirror optimization

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Macro optical system for biological application

Macro optical system for biological application

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Conference on current developments in Lens design and optical Systems engineering

作者： Kawano, Y Abe, C Abe, K Hayashi, K Hatta, Y Tamura, K Olympus Amer Inc Sci Equipment Grp Melville NY 11747 USA

ISBN: (纸本)0819437387

currently, the requirement of wide field view fluorescence observation is increasing in the biological field, but the existing microscopes have difficulty in imaging lower magnification fluorescence images. It is very easy to image in higher magnification with higher resolution and brightness using existing microscopes, but it is very difficult to image in lower magnification that are also bright. We focused on two applications in which a macro lens would be useful. The first application is DNA array reading. The second application is In Vivo imaging. Both applications require wide observation areas and bright images which are needed to lower magnification and fluorescence capability. The macro lens needs to have high numerical aperture (N..) and low magnification. We also believe if the macro lens can be attached to the existing microscopes, it will be quite useful to various applications because the scientists can then observe fluorescence images from low magnification to high magnification. To fulfill these needs, we designed macro objective lenses. Listed bellows are our macro lens' unique features. 1. Specification for the macro objective lenses are 2X, N. A. 0.14 and 4X, N. A. 0.28. These N. A. is higher than the existing microscope objective lenses of equal magnifications. 2. The 4X and 2X macro lens can be attached to existing microscopes. 3. These macro lenses can be used with the video lens such as 0.5X.

关键词： macro objective lens 4X 2X fluorescence

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Projection lenses for high resolution ablation with excimer lasers:: high performance, wide field and high UV laser power

Projection lenses for high resolution ablation with excimer ...

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Conference on current developments in Lens design and optical Systems engineering

作者： Schlichting, J Winkler, K Körner, L Schletterer, T Burghardt, B Kahlert, HJ JENOPT Laser Opt Syst GMBH Jena Germany

ISBN: (纸本)0819437387

The productive and accurate ablation of microstructures demands the precise imaging of st mask pattern onto the substrate under work. The job can be done with high performance wide field lenses as a key component of ablation equipment. The image field has dimensions of 20 to 30 mm. Typical dimensions and accuracy of the microstructures are in the order of some microns. On the other hand, the working depth of focus (DOF) has to be in the order of some 10 microns to be successful on drilling through 20 to 50 mum substrates. All these features have to be reached under the conditions of high power laser UV light Some design principles for such systems are applied, such as optimum number of elements, minimum tolerance sensitivity, material restrictions for the lens elements as well as mechanical parts (mounting), restrictions of possible power densities on lens surfaces (including ghosts), matched quality for the manufactured system. The special applications require appropriate performance criteria for theoretical calculation and measurements, which allow to conclude the performance of the application. The base is wave front calculation and measurement (using Shack-Hartmann sensor) in UV. Derived criteria are calculated and compared with application results.

关键词： laser ablation excimer laser imaging high performance optics systems design

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design of InGaN/GaN/AlGaN vertical-cavity surface-emitting lasers using electrical-thermal-optical simulation

Design of InGaN/GaN/AlGaN vertical-cavity surface-emitting l...

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Physics and Simulation of Optoelectronic Devices Viii

作者： Osinski, Marek Smagley, Vladimir A. Fu, Chun-Sheng Smolyakov, Gennady A. Eliseev, Petr G. Univ of New Mexico Albuquerque United States

3D electric-thermal-optical numerical simulator is developed and applied to model group-iii-nitride-based intracavity-contacted vertical-cavity surface-emitting lasers (VCSELs) with InGaN multi-quantum-well active region. The optical model based on the effective frequency method is combined with electrical-thermal simulator using the control volume method. Isothermal (pulsed regime imitation) and CW modes of operation are calculated over a range of voltages, covering sub-threshold spontaneous emission and lasing emission. Effects of current crowding at the active-region periphery are examined, and in particular an impact on mode profiles of spatial hole burning superimposed on nonuniform gain distribution is studied. In order to reduce the current crowding and provide more uniform gain distribution within the active region, a semitransparent p-side contact design is proposed.

关键词： Semiconductor lasers

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A review of current sensor technologies and applications within automotive and traffic control systems

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART D-JOURNAL OF AUTOMOBILE engineering 2000年第D6期214卷 589-614页

作者： Turner, JD Austin, L Transport Res Lab Crowthorne RG45 6AU Berks England Oxford Brookes Univ Oxford OX3 0BP England

This paper reviews the current practice in sensors and sensor applications for automotive and traffic control systems. Sensors to control engine fuelling, ignition and transmission (known as the powertrain) are reviewed, and the likely course of future development is discussed in the light of regulatory and market requirements as well as trends in sensor design and manufacture. Sensor needs for suspension, braking and traction control are also reviewed, and the likely introduction of wheel and tyre sensors to enhance driving safety is discussed. The recent trend towards vehicle-mounted devices to sense the vehicle environment (such as radar, optical, ultrasound, capacitive and image-based systems) is discussed, and the sensor implications of the introduction of safety-critical automotive systems such as adaptive cruise control (ACC) are discussed. Sensors for initiating the deployment of safety systems such as airbags are reviewed, together with transducers for disconnecting fuel pumps and vehicle batteries in the event of a crash. The paper includes a brief discussion of highway-based sensors for measuring vehicle speed and presence, and concludes with a discussion of the likely future developments in the field.

关键词： automotive highway traffic transducers sensors telematics control

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GRADIUM for image intensifier night vision systems for long-range target recognition

GRADIUM for image intensifier night vision systems for long-...

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current developments in Lens design and optical Systems engineering

作者： Pande, R.C. Krishna, K.Siva Rama Instruments Research & Development Establishment Dehradun India

Ever since the gradient index (GRIN) materials came into existence, there have been continuous efforts by various research groups in the world to improve these materials and explore their potential for designing high-performance and compact optical systems. Recently, with the advent of a commercial gradient index glass such as GRADIUM by LightPath Technologies Inc., Arizona, (USA) there has been an increased interest among optical engineers to use these materials for developing realisable GRIN systems. We have previously reported the use of GRADIUM in image intensifier tube based night vision systems such as passive night vision goggles for patrolling and passive night sights for drivers of armored vehicles. These applications generally use systems with unit magnification and large field of view. Derivatives of Double-Gauss configuration are best suited for the front-end objective lens of such systems. In this paper, we discuss the use of GRADIUM in night vision systems for long-range target recognition under low-level of illumination. These applications use image intensifier night vision telescopes having certain desired magnifications. The front-end objectives used for such telescopes should have large focal lengths and high apertures generally in the range of 80 mm to 140 mm for meeting the range specifications for target recognition. Petzval type of configuration is typically used for realizing such large-aperture and low f-number objectives with high contrast at lower frequencies throughout the image field. Use of conventional glass elements in such systems often limits the off-axis performance. We demonstrate, in this paper, the potential of GRADIUM in improving the overall performance of a pair of conventional Petzval objectives used in night vision devices for long range observations.

关键词： optical systems

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Combined optical/digital security devices

Combined optical/digital security devices

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optical Security and Counterfeit Deterrence Techniques iii

作者： Girnyk, Vladimir I. Tverdokhleb, Igor V. Ivanovsky, Andrey A. Optronics Ltd Kiev Ukraine

Modern holographic security devices used as emblems against counterfeiting are being more difficult as they should oppress criminal world. 2D, 3D, 3D rainbow holograms or simple diffraction structures protecting documents can not be acceptable against illegal copying of important documents, bank notes or valuable products. Recent developments in technology of optical variable devices permit world leaders to create more advanced security elements: Kinegrams, Exelgrams, Pixelgrams, Kineforms. These products are used for protecting the most confidential documents and bank notes, but now even their security level can not be enough and besides their automatic identification is vulnerable to factors of instability. We elaborate new visual security devices based on the usage of expensive and advanced technology of Combined optical/digital security devices. The technology unites digital and analogue methods of synthesis and recording of Visual security devices. The analogue methods include technique of optical holography - different combinations of 2D/3D, 3D, 2D/3D + 3D structures. Basing on them the design with elements of 3D graphic including security elements and hidden machine-readable images are implemented. The digital methods provide synthesis of optical Variable Devices including special security elements, computer generated holograms and Kineforms. Using them we create determined and quasi-random machine-readable images. Recordings are carried out using the combined optical and electronic submicrometer technology elaborated by Optronics Ltd. The results obtained show effectiveness of the combined technology permitting to increase the security level essentially that should increase tamper and counterfeit resistance during many years.

关键词： Security of data

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Magneto-optical Recording Materials

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2000年

作者： Richard J. Gambino Takao Suzuki

ISBN: (纸本)9780780310094

"As digital data storage technology undergoes enormous change, electrical engineers, physicists, and materials scientists need to keep pace with the materials requirements for recording media. Expert contributors -- together with world-class authorities Richard J. Gambino and Takao Suzuki -- bring you a practical, comprehensive guide to materials design and selection for magneto-optical storage media. This authoritative book explores multilayered thin films, exchanged coupled layers, materials used in current products, and materials of potential interest not yet available in practical applications. A detailed analysis concerning the physics of magneto-optical recording will help you make informed decisions about materials properties. You will also find an extensive discussion of systems and engineering design features for magneto-optical storage devices. This discussion will help you to understand how materials properties impact system performance. You will gain additional insight into this fast-developing field through in-depth coverage of these featured topics: * Rare earth-transition metal amorphous alloys, multilayers, garnets, intermetallic compounds, and ferrites * Basic principles of domain dynamics and recording physics * Latest developments in exchange coupled layers, direct overwrite, and magnetic superresolution * Minidisc, future high-density systems, and DVD format. MAGNETO-optical RECORDING MATERIALS is essential reading for anyone who needs to keep up-to-date with the latest advances in digital data storage technology."

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