Proceedings Volume 5663

Photonics in the Automobile

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Proceedings Volume 5663

Photonics in the Automobile

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Volume Details

Date Published: 16 February 2005
Contents: 6 Sessions, 30 Papers, 0 Presentations
Conference: European Workshop on Photonics in the Automobile 2004
Volume Number: 5663

Table of Contents

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Table of Contents

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  • Session 3
  • Session 1
  • Session 3
  • Session 4
  • Session 2
  • Session 1
  • Poster Session
  • Session 4
  • Poster Session
  • Working Group Session
  • Session 4
  • Poster Session
Session 3
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Lighting innovations in concept cars
Stephan Berlitz, Wolfgang Huhn
Concept cars have their own styling process. Because of the big media interest they give a big opportunity to bring newest technology with styling ideas to different fairgrounds. The LED technology in the concept cars Audi Pikes Peak, Nuvolari and Le Mans will be explained. Further outlook for the Audi LED strategy starting with LED Daytime Running Lamp will be given. The close work between styling and technical engineers results in those concept cars and further technical innovations based on LED technologies.
Session 1
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LED frontlighting
The "light emitting diode", or LED for short, has already made a name for itself as an alternative luminant for vehicle lighting applications. Lighting functionalities on the interior and on the rear of the vehicle in particular benefit from the advantages of LEDs such as reliability and compactness. Thanks to the rapid increase in power in LEDs, applications in headlamps can now also be represented. This paper focuses on the use of white high-power LEDs in headlamps. As well as explaining the structure of LEDs and how they work, their technical properties in comparison with conventional light sources will also be discussed. In addition, system requirements and LED frontlighting applications will be presented.
Session 3
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LED rear combination lamps: styling, robustness, life, packaging, installation, and opportunities for intelligent signal lighting
Stefan Eberle, Leonard Livschitz, Jeffrey Raggio
The automotive industry is rapidly increasing the adoption of LED technology in all vehicle lighting applications. In the near future, LED solutions are expected to capture significant market share for exterior signal lighting. This paper will investigate why LED signal lighting is important to automotive OEMs and consumers, and will exhibit how the latest product development from Lumileds Lighting can enable the ultimate RCL application: a single LED instead of a conventional light bulb.
Session 4
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Solid state night vision systems
Jorg Moisel
The risk for a fatal traffic accident is 4 - 5 times higher at night compared to the day. Since 1998, night vision systems can help drivers to better recognize dangers at night. For active night vision systems, solid state sources for infrared headlights promise the technically best solution as they can be operated with wavelengths close to the maximum possible camera sensitivity. Both lasers and IRED arrays can be used. Whereas the laser is technically superior, IREDs offer a more economical system.
Session 2
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Technology and design
The requirement of vehicle manufacturers for possibilities of differentiation on the one hand and the compelling technical necessity to provide low-profile lamp concepts on the other have led to a wide range of light guide applications being introduced in passenger vehicles in the past few years. This paper will provide a summary of light guide technology and illustrate the outlook for future lamp concepts using the example of non-contact switching. The paper also deals with the interaction of technical, design-oriented and ergonomic points of view during the creation of new products.
Session 1
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Integration of LEDs in forward lighting
Luca Sardi, Ralf Ackermann
In the last years the application of LEDs for automotive signaling functions has become even more important making feasible a wide variety of stylistic and technical solutions. Nevertheless, the continuous improving of white LEDs performances seems to be suitable for the application of these sources also for the headlamp main functions. In this paper different solutions will be shown and discussed, with particular attention to the optical design issue as well as to the electronic and thermal management.
Poster Session
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A global simulation approach to optics, lighting, rendering, and human perception for the improvement of safety in automobiles
Jacques Delacour, Laurent Fournier, Jean-Pierre Menu
In order to provide optimum comfort and safety conditions, information must be seen as clearly as possible by the driver and in all lighting conditions, by day and by night. Therefore, it is becoming fundamental to anticipate in order to predict what the driver will see in a vehicle, in various configurations of scene and observation conditions, so as to optimize the lighting, the ergonomics of the interfaces and the choice of surrounding materials which can be a source of reflection. This information and choices which will depend on it, make it necessary to call upon simulation techniques capable of modeling, globally and simultaneously, the entire light phenomena: surrounding lighting, display technologies, the inside lighting, taking into consideration the multiple reflections caused by the reflection of this light inside the vehicle. This has been the object of an important development, which results in the solution SPEOS Visual Ergonomics, led by company OPTIS. A unique human vision model was developed in collaboration with worldwide specialists in visual perception to transform spectral luminance information into perceived visual information. This model, based on physiological aspects, takes into account the response of the eye to light levels, to color, to contrast, and to ambient lighting, as well as to rapid changes in surrounding luminosity, in accordance with the response of the retina. This unique tool, and information now accessible, enable ergonomists and designers of on board systems to improve the conditions of global visibility, and in so doing the global perception of the environment that the driver will have.
NICOLAU: compact unit for photometric characterization of automotive lighting from near-field measurements
Santiago Royo, Maria Jesus Arranz, Josep Arasa, et al.
The present works depicts a measurement technique intended to enhance the characterization procedures of the photometric emissions of automotive headlamps, with potential applications to any light source emission, either automotive or non-automotive. A CCD array with a precisely characterized optical system is used for sampling the luminance field of the headlamp just a few centimetres in front of it, by combining deflectometric techniques (yielding the direction of the light beams) and photometric techniques (yielding the energy travelling in each direction). The CCD array scans the measurement plane using a self-developed mechanical unit and electronics, and then image-processing techniques are used for obtaining the photometric behaviour of the headlamp in any given plane, in particular in the plane and positions required by current normative, but also on the road, on traffic signs, etc. An overview of the construction of the system, of the considered principle of measurement, and of the main calibrations performed on the unit is presented. First results concerning relative measurements are presented compared both to reference data from a photometric tunnel and from a plane placed 5m away from the source. Preliminary results for the absolute photometric calibration of the system are also presented for different illumination beams of different headlamps (driving and passing beam).
Triangulation-based laser range finder with CMOS image sensor in automotive field
Jih-Huah Wu, Rong-Sen Chang, Sheng-Pin Su
A prototype of range finder using a CMOS image sensor and a pulsed laser is developed for the automotive field. The system presented here is based on optical triangulation. The gravity of the infrared laser spot on CMOS image sensor is converted into pixel coordinates proportional to the distance to be measured. Based on the experimental tests of the system, it was found that the distance could be estimated with accuracy better than 2% within the range of 5 to 45 meters.
Measurement method for sun effects on target’s chromaticity and luminance
Hsueh-Ling Yu, Chin-Chai Hsiao
The luminance and color of a traffic sign depend on the angle, illuminance, and spectrum of the illuminating sunlight. The general method for measuring the effects of sun on traffic signs is to use Xe source or Xe source with filters as a sun-simulator to simulate the CIE defined average sunlight spectrum, D65. The disadvantages of using the sun-simulator are the high cost and measurement error that arises from the difference between the spectrum of the sunlight and that of sun-simulator. Using Xe source as the sun-simulator may produce an error of around 3.5% due to the spectrum difference. To solve these problems, a measurement method has been applied to eliminate the need for sun-simulator in measuring the sun effect on traffic signs. Measuring the spectral reflectance of the target and calculating a luminance and illuminance translation factor allow us to calculate the luminance reflected from the target, regardless of the light source illuminating on it. For instance, the effects of other sunlight spectra, such as D55 or D75, on the targets can also be determined by this method without the use of any light source to simulate D55 or D75. The sunlight spectrum in the presented simulation equation is obtained directly from the CIE definition, eliminating the error associated with the difference between the sun simulator and sunlight spectra. The experimental results demonstrate that the calculated luminance is about 1% different from the measurement results. Low cost, good accuracy and high flexibility are the advantages of this method.
Lane detection algorithm for an onboard camera
Mario Bellino, Yuri Lopez de Meneses, Peter Ryser, et al.
After analysing the major causes of injuries and death on roads, it is understandable that one of the main goals in the automotive industry is to increase vehicle safety. The European project SPARC (Secure Propulsion using Advanced Redundant Control) is developing the next generation of trucks that will fulfil these aims. The main technologies that will be used in the SPARC project to achieve the desiderated level of safety will be presented. In order to avoid accidents in critical situations, it is necessary to have a representation of the environment of the vehicle. Thus, several solutions using different sensors will be described and analysed. Particularly, a division of this project aims to integrate cameras in automotive vehicles to increase security and prevent driver's mistakes. Indeed, with this vision platform it would be possible to extract the position of the lane with respect to the vehicle, and thus, help the driver to follow the optimal trajectory. A definition of lane is proposed, and a lane detection algorithm is presented. In order to improve the detection, several criteria are explained and detailed. Regrettably, such an embedded camera is subject to the vibration of the truck, and the resulting sequence of images is difficult to analyse. Thus, we present different solutions to stabilize the images and particularly a new approach developed by the "Laboratoire de Production Microtechnique". Indeed, it was demonstrated in previous works that the presence of noise can be used, through a phenomenon called Stochastic Resonance. Thus, instead of decreasing the influence of noise in industrial applications, which has non negligible costs, it is perhaps interesting to use this phenomenon to reveal some useful information, such as for example the contour of the objects and lanes.
LED headlamps: the spiny path to a legal headlamp
Since two decades, LEDs are used as light sources in the automobile industry. However, up to now, their usage was restricted to low lumen applications like dashboard lighting and exterior signal lighting. With the advent of very high brightness LEDs, now the time is ready to tackle also the most demanding application, the front forward lighting. Schefenacker actively works on the realisation of an LED headlamp. From this research work, several optical concepts for the realization of LED front forward lighting and their impact on the light source and on the lighting performance are presented. The advantages and challenges coming with the realisation of an LED headlamp are discussed. An outlook on future developments of LED forward lighting is given, e.g. possibilities with AFS or car to car communication. A short discussion of the legal situation with LED headlamps is added, including an outlook of the expected dates for legalization.
Session 4
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Intelligent rear lighting: a breakthrough for safety and comfort
Since the invention of automobiles, rear lamps suffered from poor visibility in bad weather or due to lamp soiling. With the advent of advanced sensor systems and powerful microcontrollers, it is possible to adjust the light output of signalling applications to the visibility conditions. Latest LED technology allows to control the light output of signal lamps between almost zero cd and several hundred cd. Schefenacker has developed a system to improve the visibility of signal lamps by adaptation of the lighting levels to the environmental conditions. A detector system, consisting of a Lidar sensor and a combined brightness/dirt sensor detects the environmental conditions. A microcontroller transfers these data into necessary brightness levels for the intelligent rear lamp. The intensity of the signalling function is adapted accordingly, to guarantee a consistent perception even under bad weather conditions. This will affect positively the road safety, especially under strongly varying brightness conditions and in foggy weather. The system offers also the opportunity to get an automatically working fog lamp. Finally, the legal situation is highlighted. Since the implementation requires continuously varying intensity levels, the respective ECE regulations have to be adopted. Extensive work has been done since the first ideas for an adaptive tail lamp, and it is expected that the regulations will be adapted soon.
Poster Session
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PCS optical fibers for an automobile data bus
James P. Clarkin, Richard J. Timmerman, Gary W. Stolte, et al.
Optical fibers have been used for data communications in automobiles for several years. The fiber of choice thus far has been a plastic core/plastic clad optical fiber (POF) consisting of the plastic polymethylmethacrylate (PMMA). The POF fiber provides a low cost fiber with relatively easy termination. However, increasing demands regarding temperature performance, transmission losses and bandwidth have pushed the current limits of the POF fiber, and the automotive industry is now moving towards an optical fiber with a silica glass core/plastic clad (PCS). PCS optical fibers have been used successfully in industrial, medical, sensor, military and data communications systems for over two decades. The PCS fiber is now being adapted specifically for automotive use. In the following, the design criteria and design alternatives for the PCS as well as optical, thermal, and mechanical testing results for key automotive parameters are described. The fiber design tested was 200μm synthetic silica core/230μm fluoropolymer cladding/1510μm nylon buffer. Key attributes such as 700 - 900 nm spectral attenuation, 125°C thermal soak, -40 to 125°C thermal cycling, bending losses, mechanical strength, termination capability, and cost are discussed and compared. Overall, a specifically designed PCS fiber is expected to be acceptable for the use in an automotive data bus, and will show improvement in optical transmission, temperature range and bandwidth. However, the final selection of buffer and jacket materials and properties will be most dependent on the selection of a reliable and economical termination method.
Strength and reliability of silica optical fibers for automotive communication networks
Demand for new safety, sensor, control, information and entertainment technologies in automobiles is stretching the data rate limits of communication networks using conventional wiring and plastic-based fibers. Thus far, the switch to high-bandwidth glass optical fibers has been hindered by concerns about the fiber’s reliability. In this study, we present zero-stress aging data for glass optical fibers with different protective coatings exposed to environmental conditions relevant to the automotive industry.
Red VCSEL for automotive applications
Robert Rossbach, Tabitha Ballmann, Rainer Butendeich, et al.
In this paper we discuss the problems of the AlGaInP material system and its consequences for the laser applications in vertical-cavity surface-emitting lasers (VCSEL). The epitaxial and technological solutions to overcome at least parts of the inherent problems were presented. Measured power-current curves of 660nm AlGaInP-based oxide-confined VCSEL are compared with calculated data by a cylindrical heat dissipation model to improve heat removal out of the device. Pulsed lasing operation of a 670nm VCSEL at +120°C heat sink temperature is demonstrated, where we exceeded 0.5mW and at +160°C still 25μW output power were achieved. We also studied the modulation bandwidth of our devices and achieved 4GHz and calculations lead to a maximum possible intrinsic -3dB frequency of 25GHz.
Dependecy of the reaction time from the overlap of signal lights with different colors
The rearward signal aspect consists of lights with different colors. With standard technics these signal lights are located at different places. With new technics it is possible to build signal lights with different colors together in one place. The signals overlap. In experiments at the University of Karlsruhe we studied the dependency between reaction time and overlap of signal lights. We can see, that the total overlap from a yellow turn signal and a red brake signal will increase the reaction time. The increase depends of the ratio between the luminance of the turn indicator signal and the luminance of the brake signal. With a ratio from one to one (best case with minimal increase) we found an increase of 300 milli seconds.
Far-infrared cameras for automotive safety
Jacques Lonnoy, Yann Le Guilloux, Raphael Moreira
Far Infrared cameras used initially for the driving of military vehicles are slowly coming into the area of commercial (luxury) cars while providing with the FIR imagery a useful assistance for driving at night or in adverse conditions (fog, smoke, ...). However this imagery needs a minimum driver effort as the image understanding is not so natural as the visible or near IR one. A developing field of FIR cameras is ADAS (Advanced Driver Assistance Systems) where FIR processed imagery fused with other sensors data (radar, ...) is providing a driver warning when dangerous situations are occurring. The communication will concentrate on FIR processed imagery for object or obstacles detection on the road or near the road. FIR imagery highlighting hot spots is a powerful detection tool as it provides a good contrast on some of the most common elements of the road scenery (engines, wheels, gas exhaust pipes, pedestrians, 2 wheelers, animals,...). Moreover FIR algorithms are much more robust than visible ones as there is less variability in image contrast with time (day/night, shadows, ...). We based our detection algorithm on one side on the peculiar aspect of vehicles, pedestrians in FIR images and on the other side on the analysis of motion along time, that allows anticipation of future motion. We will show results obtained with FIR processed imagery within the PAROTO project, supported by the French Ministry of Research, that ended in spring 04.
Resonant microcavity light emitters for onboard exhaust emissions IR sensor
Francois Levy, Emmanuel Picard, Johan Rothmann, et al.
A sensor based on selective optical absorption allows monitoring of hazardous engine exhaust emissions such as gaseous hydrocarbons and carbon monoxide. The IR components presented here offer the potential to develop a compact, fast and selective sensor reaching the technical and cost requirements for on-board automotive applications. Optical gas monitoring requires light sources above 3μm since most of the gas species have their fundamental absorption peaks between 3 and 6 μm. We report here on resonant microcavity light sources emitting at room temperature between 3 and 5μm. The emitter combines a CdxHg1-xTe light emitting heterostructure and two dielectric multilayered mirrors. It is optically pumped by a commercial III-V laser diode. The principle of the resonant microcavity emitter allows tailoring of the emission wavelength and the line width to fit the absorption band of a specific gas, ensuring a very good selectivity between species. Moreover, this kind of emitter allows fast modulation enabling high detectivity and short response time. We report performances of light sources in the range 3-5μm allowing the detection of hydrocarbons and carbon monoxide. Association of emitters peaking at different characteristic wavelengths with a single broad band detector allows designing of an optical sensor for several gas species. Sensitivity and time response issues have been characterized: detection of less than 50ppm of CH4 on a 15cm path has been demonstrated on synthetic gas; analysis of exhaust gases from a vehicle has allowed cylinder to cylinder resolution. This optical sensor offers the potential of various on-board automotive applications.
Moulded infrared optics making night vision for cars within reach
Antoine Bourget, Yann Guimond, John Franks, et al.
Sustainable mobility is a major public concern, making increased safety one of the major challenges for the car of the future. About half of all serious traffic accidents occur at night, while only a minority of journeys is at night. Reduced visibility is one of the main reasons for these striking statistics and this explains the interest of the automobile industry in Enhanced Night Vision Systems. As an answer to the need for high volume, low cost optics for these applications, Umicore has developed GASIR. This material is transparent in the NEAR and FAR infrared, and is mouldable into high quality finished spherical, aspherical and diffractive lenses. Umicore's GASIR moulded lenses are an ideal solution for thermal imaging for cars (Night Vision) and for sensing systems like pedestrian detection, collision avoidance, occupation detection, intelligent airbag systems etc.
CMOS chip technology for automotive imagers
Hans Stoehr, Chris Softley
Photonfocus AG in Switzerland develops and produces image sensors for automotive applications. This presentation shows the special requirements for imager chips in automobiles and gives some examples of automotive-qualified image sensors based on CMOS technology. The results point out the principal advantages of CMOS chip technology in comparison to CCD. In addition, there is an outlook for the next generation of automotive CMOS sensors.
Working Group Session
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Opportunities and challenges for photonics in the automotive
Eric Mounier, Jean-Christophe Eloy, David Jourdan
In the future, photonics will enable the marketing of new functions in cars to make them more secure, more fuel-efficient with improved design. Today, there are already photonics devices used in cars such as HB LEDs for brake or interior lights, and optical rain sensors for automatic wipers. Moreover, optical multiplexing for multimedia applications and head-up displays are now starting to be implemented in high-end cars and some more complex devices are already at the prototyping level. This is the case for example for driver information flat panel displays or optical sensors for occupant sensing. This paper gives an overview of the current and future optical applications in cars. So far, applications of displays, lighting, security and datacom are driving the market for photonics in cars. Moreover, car design is also one of the most important market drivers in automobile. Then, photonics could also become a strategic imperative for a company in the design of new cars that will emphasize differentiation from existing competitors. Lighting could then become a signature of the car manufacturer thanks to photonics technology.
Session 4
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Laser diodes for sensing applications: adaptive cruise control and more
Joerg Heerlein, Stefan Morgott, Christian Ferstl
Adaptive Cruise Controls (ACC) and pre-crash sensors require an intelligent eye which can recognize traffic situations and deliver a 3-dimensional view. Both microwave RADAR and “Light RADAR” (LIDAR) systems are well suited as sensors. In order to utilize the advantages of LIDARs -- such as lower cost, simpler assembly and high reliability -- the key component, the laser diode, is of primary importance. Here, we present laser diodes which meet the requirements of the automotive industry.
Poster Session
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Compact illumination and camera systems for 2D and 3D sensing in automobile applications
The use of optical sensor principles in automotive applications is growing fast due to the increasing demand for driver assistance and passenger security systems. Automotive applications demand for compact, low volume or particularly flat microoptical systems for recognition of passengers and obstacles, measuring distances, eye movements etc. The optical concepts need to reach a high level of optical- and opto-electronic integration and demand a high degree of modularity to be able to address different requirements in a flexible way. In this context, the design and realization of several compact optical modules for the sensor as well as for the illumination side are presented, e.g. a wide angle camera optics (FOV = 90° and f-number = 1.1), laser and LED-based illumination modules and an ultra thin camera of 0,2 mm length, based on the apposition eye principle. The specification of these microoptical modules is oriented to fulfil physical as well as economical requirements. In particular, a great compactness and easy scalable fabrication technologies are essential to fulfil the different boundary constraints.
Dow Corning photonics: the silicon advantage in automotive photonics
Terry V. Clapp, Rene Paquet, Ann Norris, et al.
The Automotive Market offers several opportunities for Dow Corning to leverage the power of silicon-based materials. Dow Corning Photonics Solutions has a number of developments that may be attractive for the emergent photonics needs in automobiles, building on 40 years of experience as a leading Automotive supplier with a strong foundation of expertise and an extensive product offering- from encapsulents and highly reliable resins, adhesives, insulating materials and other products, ensuring that the advantage of silicones are already well-embedded in Automotive systems, modules and components. The recent development of LED encapsulants of exceptional clarity and stability has extended the potential for Dow Corning’s strength in Photonics to be deployed “in-car”. Demonstration of board-level and back-plane solutions utilising siloxane waveguide technology offers new opportunities for systems designers to integrate optical components at low cost on diverse substrates. Coupled with work on simple waveguide technology for sensors and data communications applications this suite of materials and technology offerings is very potent in this sector. The harsh environment under hood and the very extreme thermal range that materials must sustain in vehicles due to both their engine and the climate is an applications specification that defines the siloxane advantage. For these passive optics applications the siloxanes very high clarity at the data-communications wavelengths coupled with extraordinary stability offers significant design advantage. The future development of Head-Up-Displays for instrumentation and data display will offer yet more opportunities to the siloxanes in Automotive Photonics.
3D-TOF sensors in the automobile
In recent years, pervasive computing has become an important topic in automobile industry. Besides well-known driving assistant systems such as ABS, ASR and ESP several small tools that support driving activities were developed. The most important reason for integrating new technologies is to increase the safety of passengers as well as road users. The Centre Suisse d'Electronique et de Microtechnique SA (CSEM) Zurich presented the CMOS/CCD real-time range-imaging technology, a measurement principle with a wide field of applications in automobiles. The measuring system is based on the time-of-flight measurement principle using actively modulated radiation. Thereby, the radiation is emitted by the camera's illumination system, reflected by objects in the field of view and finally imaged on the CMOS/CCD sensor by the optics. From the acquired radiation, the phase delay and hence the target distance is derived within each individual pixel. From these distance measurements, three-dimensional coordinates can then be calculated. The imaging sensor acquires its environment data in a high-frequency mode and is therefore appropriate for real-time applications. The basis for decisions which contribute to the increased safety is thus available. In this contribution, first the operational principle of the sensor technology is outlined. Further, some implementations of the technology are presented. At the laboratories of the Institute of Geodesy and Photogrammetry (IGP) at ETH Zurich an implementation of the above mentioned measurement principle, the SwissRanger, was investigated in detail. Special attention was focused on the characteristics of this sensor and its calibration. Finally, sample applications within the automobile are introduced.
LED light sources for head-up displays
The concept of Head-Up Displays is simple: move the important information a driver needs to see up into their line of sight, so they don’t have to take their eyes off the road. A projected image appears to be floating freely over the hood, at a distance of approximately two meters. Mirrors direct light from an image-generating LCD to the windshield where it is superimposed with the driver’s field of view. The LCD is lit with an appropriate light source. Requirements like long lifetime, vibration resistance, thermal stability and high luminance make LED light sources ideal for use in the automotive industry. The paper discusses the principles of the optical system design of an LED light source for Head-Up Displays.
Low-cost uncooled IRFPA and molded IR lenses for enhanced driver vision
Olivier Legras, Arnaud Crastes, Jean-Luc Tissot, et al.
Uncooled infrared focal plane arrays are being developed for a wide range of thermal imaging applications. CEA/LETI developments are focused on the improvement of their sensitivity enabling the possibility to reduce the pixel pitch and the decrease of the system cost by using smaller optics. We present the characterization of a 160 x 120 infrared focal plane array with a pixel pitch of 35 μm. The amorphous silicon based technology is using recent process enhancement developed by CEA/LETI and transferred to ULIS. ULIS developed for this device a low cost package. The readout integrated circuit structure is using an advanced skimming function to enhance the pixel signal exploitation. This device is well adapted to high volume infrared imaging applications where spatial resolution (in term of pixel number) is less important than cost. The electro-optical characterization is presented. Besides, a unique and high precision molding technology has been developed by Umicore IR Glass to produce low cost chalcogenide infrared glass lenses with a high performance level. Spherical, aspherical and asphero-diffractive lenses have been manufactured with very accurate surface precision. The performances are comparable to those of an optic made with aspherical germanium. This new glass named GASIR offers an alternative solution to germanium for thermal imaging, especially for medium and high volumes applications. These two key technologies are well adapted to develop infrared driver vision enhancement (DVE) system for commercial application. A European project named ICAR has been setting up to exploit these advantages. An overview of the project will be given.
Replicated micro-optics for automotive applications
Benno Stager, Michael T. Gale, Markus Rossi
Replicated micro-optics is playing an increasingly important role in illumination and sensing systems in automobiles. The introduction of new design methods and improvements in materials and production technology has led to components which can offer superior performance, size and weight compared with classical optical elements. Diffractive Optical Elements (DOEs) for applications such as beam shaping can achieve optical performance which is not possible with conventional optics. Beam forming elements for use with red and white LEDs play a major role in automotive optics. Customised DOEs can offer significantly more design flexibility and functionality over Fresnel lenses for the complex optical system based on a single or multiple LED source with reflector and wavelength converting resin. Thinner modules and improved efficiency are achieved. With CMOS imager sensors, micro-optical lenslet arrays can improve the effective sensitivity by many factors. UV-embossing and injection moulding are used to produce components in high volumes at low production costs. Replicated mounting and alignment features reduce assembly costs. New materials and processes have been developed to enable wafer-scale production by UV-embossing, producing glass-like components with excellent humidity and elevated temperature stability as well as IR-reflow process compatibility.
High dynamic range vision sensor for automotive applications
Eric Grenet, Steve Gyger, Pascal Heim, et al.
A 128 x 128 pixels, 120 dB vision sensor extracting at the pixel level the contrast magnitude and direction of local image features is used to implement a lane tracking system. The contrast representation (relative change of illumination) delivered by the sensor is independent of the illumination level. Together with the high dynamic range of the sensor, it ensures a very stable image feature representation even with high spatial and temporal inhomogeneities of the illumination. Dispatching off chip image feature is done according to the contrast magnitude, prioritizing features with high contrast magnitude. This allows to reduce drastically the amount of data transmitted out of the chip, hence the processing power required for subsequent processing stages. To compensate for the low fill factor (9%) of the sensor, micro-lenses have been deposited which increase the sensitivity by a factor of 5, corresponding to an equivalent of 2000 ASA. An algorithm exploiting the contrast representation output by the vision sensor has been developed to estimate the position of a vehicle relative to the road markings. The algorithm first detects the road markings based on the contrast direction map. Then, it performs quadratic fits on selected kernel of 3 by 3 pixels to achieve sub-pixel accuracy on the estimation of the lane marking positions. The resulting precision on the estimation of the vehicle lateral position is 1 cm. The algorithm performs efficiently under a wide variety of environmental conditions, including night and rainy conditions.