The hottest photonics technology will play a big r

2022-08-23
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Photonics technology will play a big role in automotive applications

from LED headlights, night vision safety systems to emerging laser ignition systems, photonics technology is playing a big role in automotive applications with its advantages of compactness, low energy consumption and high performance

at present, optics and photonics technology is providing an increasingly rich "toolkit" for automobile manufacturers to help them improve the safety of automobiles, reduce long-term costs, improve efficiency, and add unique design elements to automobiles. In addition to the common LED tail lights, some cars are also trying LED headlights. At the same time, optical fiber is also being used to connect communication and display devices in cars. It is reported that Ford is currently investigating the laser ignition system of cars, while some high-end cars will also provide night vision systems and driver assistance systems

led taillights and headlights

"although the cost of using LED solutions for automotive taillights and interior lights is still much higher than that of incandescent lamps, the huge advantages of LED solutions have been enough to enable automotive manufacturers to accept their higher costs in development and manufacturing." Professor Cornelius Neumann, who specializes in automotive lighting at the University of Karlsruhe in Germany, said, "In addition to the long service life of LED (its service life is usually longer than that of automobile), its fast response time is also an important safety factor of brake lamp. Generally, the response time of LED is about 7 shorter than that of common bulbs. When loading the sample of hydraulic universal testing machine, attention should be paid to the operation of 5 milliseconds. In addition, the low power consumption and novel shape of LED are also the main reasons why manufacturers choose LED as automobile signal."

neumann and Hella, a German supplier of automotive lighting and electronic products, have conducted in-depth research in the field of automotive lighting for 11 years. He said that although led taillights are common in cars, cars are faced with more comprehensive quality inspection when using LED headlights! Challenges

"so far, at least three models of cars on the market have adopted LED headlights: Lexus LS 600, Audi R8 and Cadillac Escalade platinum." Professor Neumann said, "but there are still many problems to be solved when using LED solutions in headlights."

Professor Neumann pointed out that dust, humidity, mechanical vibration and the harsh environment with the surrounding temperature of about 90 ° C will bring some challenges to the LED, because the performance of the LED will decline with the increase of temperature, so some high-power LEDs need to be equipped with cooling devices. Moreover, instead of using a single light source (such as halogen lamp or high intensity discharge (HID) lamp), LED headlights should be assembled with multiple LEDs to meet the needs of driving signal lighting. [1] In LED headlights, three different optical systems are usually used to achieve different functions. These three systems need to be firmly matched with each other to emit light with sufficient brightness to meet the requirements of road driving lighting

although LED headlights still face many challenges, Professor Neumann added that compared with common bulb solutions, led solutions can save 50% or more energy consumption (see Table 1). [2] According to some studies, less than 20% of the LED light can be used to obtain the same brightness as the HID lamp, and the LED lighting is safer. [3] With the development of mathematical models and software algorithms, engineers can now design and produce various forms of mirrors and lenses to guide the light from the light source to specific areas of the traffic road (see Figure 1)

Figure 1: all headlights of Opel Signum cars adopt led solutions, which use different modules to achieve different signal functions: six groups of LEDs are used for low beam lights; The bottom three groups of LEDs are used for high beam lamps; Two groups of small LEDs on the side are used for corner lights; 10 sets of LEDs are used as daytime running lights. The direction indicator lamp is composed of three groups of LEDs with reflection system located on the top of the headlamp. Different LEDs are selected according to the different uses of each signal lamp

Table 1: comparison between traditional lighting methods and LED lighting power consumption

high brightness LED manufacturers have good reasons to believe that led will penetrate into the automotive field in the future. Strategies unlimited, a market research company, predicts that by 2013, the overall market size of global automotive LED outdoor lighting will increase from US $158million in 2008 to US $347million. In addition, according to the "global and Chinese automotive LED Lighting Industry Research Report" of researchinchina, by 2014, LED headlights will be comparable with traditional hid headlights in cost and performance (assuming that led technology can continue to progress at the current rate of development). At that time, the application of LED in the automotive field will be greatly improved, and the market size of automotive headlights alone will reach US $122 million

night vision system

BMW's bmw-7 series vehicles adopt the second generation night vision 2 night vision system of Autoliv company in Sweden, which adopts a far-infrared sensor to scan pedestrians on the road, and its night vision distance is three times that of low beam lamps. When pedestrians or animals are detected in front of the vehicle, the system will automatically analyze the scene and vehicle dynamics, assess the risk of the driver hitting the target, and send an alarm to the driver who is difficult to distinguish the breaking load from the maximum load when necessary (for example, send an alarm through the on-board display, see Figure 2). "Autoliv's latest night vision adds a friction system between the working cylinder and the piston and when the guide wheel on the side of the workbench moves along the pillar, which improves the safety of driving at night to a new level, and provides the driver with 'another eye' on the road at night." Stuart klapper, general manager of Autoliv night vision system, said

Figure 2: when a man is detected crossing the road in front of the car at night, the far-infrared night vision system of BMW bmw-7 series cars sends an alarm to the driver

in the urban road sections with slow driving speed and high pedestrian flow, the system only monitors the relatively small range in close range on the road to avoid excessive alarms; In rural roads with high speed and few people, the road range monitored by the system will be expanded accordingly. In order to make timely and corresponding adjustments to the monitoring range, Autoliv's night vision system continuously collects night vision video images from the surrounding environment, and uses a set of advanced software algorithms to detect more than 50 million "image fragments", and sends corresponding alarm signals to drivers

the far-infrared camera used in Autoliv's night vision system uses 320 × The 240 pixel vanadium oxide thermal radiometer has a germanium window to protect the camera lens from external damage. Klapper said, "compared with the first generation camera, we have successfully reduced the cost of lens by as much as 30%

Siemens VDO also developed an infrared night vision system with a working distance of 150 meters, which generates an electronically processed video image for real-time display in cars. The system has two working modes: one is a near-infrared system, in which the light generated by two infrared transmitters integrated into the headlights is captured by a small camera installed near the rearview mirror; Another way is to use the long wave infrared system, which requires installing a camera and using a sensor working within the range of 6 ~ 12 m to detect the thermal radiation from the surrounding environment of the vehicle. Once human or animal is detected, the system will display the object in a bright form

laser ignition

in the summer of 2009, Ford announced that it was working with GSI group and the University of Liverpool in the United Kingdom to develop a laser ignition system for the next generation of automotive engines. In fact, as early as the late 1970s, people began to study laser ignition systems. At that time, many research papers on laser ignition systems had begun to appear in various automotive technology conferences

because the laser can be decomposed into multiple beams, multiple ignition points will improve the chance of complete combustion of fuel in the engine, so as to reduce emissions and improve the combustion efficiency of fuel in cold and wet conditions. Even a part of the laser energy can be transmitted back to provide information about how the engine operates, so that the proportion of air/fuel mixture can be automatically adjusted to achieve better fuel utilization. Ford also said it plans to provide laser sparks through an optical cable, which will take up less space than spark plugs, allowing the use of larger and more efficient engine valves to achieve more fuel combustion

in 2007, researchers at the National Energy Technology Laboratory () of the United States have designed a laser ignition system combined with internal combustion engines. In this system, 10ns pulses from a 1.06 m laser are focused into the cylinder through the spark plug port to generate ignition sparks. Compared with the traditional single cylinder, four stroke, spark ignition engine, the use of laser spark ignition system can not only reduce engine emissions, but also improve fuel combustion efficiency

driver assistance system

in addition to lighting and night vision applications, there are also driver assistance systems based on photonics technology. Land Rover of Valeo group and bmw-5 series vehicles are equipped with driver assistance system. The whole system includes five cameras: a wide-angle camera installed at the rear of the car for parking assistance; Two cameras installed on the left and right sides of the front bumper are used to assist the driver to observe pedestrians or other objects approaching the vehicle when the vehicle enters the street with poor visibility; The other two cameras installed on the two side mirrors are used to directly monitor the environment around the vehicle

panomorph technology is a wide-angle lens technology patented by Canadian immervision company. This technology can improve the angular resolution in a specific area of an image field of view, and place the target area of interest in the center or edge of the image (see Figure 3). [4] There are also specific windows for drivers to observe the situation, and some synchronous visual images can be used for road condition analysis. For example, through an intelligent cruise control system, many applications such as collision avoidance system, blind area viewing, pedestrian and road sign detection, lane tracking and so on can be integrated

Figure 3: multiple synchronous undistorted images from a panomorph camera can play the role of driving assistance, such as helping drivers avoid collisions and assist in parking

Alain marchildon, vice president of customized panoramic applications of immervision, said: "At present, Samsung has signed relevant production and distribution license agreements with immervision, and its first automotive tier 2 will provide a panomorph automotive vision module. The 360 ° panoramic vision system can realize new enhanced panoramic browsing and sensing applications, which can greatly reduce the casualties related to collision and provide a safer driving environment for drivers and passengers."

References:

1 S. Tedde et al., Nano Letters 9, p. 980 (2009).

2. T. Rauch et al., Nature Photonics 3, p. 332 (2009).

3. G. Xiong et al., Science 325, p. 1665 (2009).

4. G. Konstantatos et al., Nature 442, p. 180 (2006). (end)

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