Active night vision systems for automotive use operate in the wavelength range of near infrared (NIR), which is close above the visible radiation (VIS). Silicon-based CCD- or CMOS-arrays are sensitive up to a wavelength of about 1100nm and can therefore be used instead of passive night vision devices with their noisy low-resolution pictures. Since the purpose is to reveal potentially dangerous objects which may be as far as 100 or 200m from the observing camera, the NIR illuminator(s) as part of the system must provide a sufficient irradiance in terms of Watt per square meter on the target. Halogen automotive lamps are used as NIR radiation sources, because the maximum emission of these lamps matches the NIR-sensitivity of a silicon-based camera. In order to create an invisible beam the otherwise welcome light emission of halogen lamps must be suppressed by some kind of filter. Such a filter should have a high transmission above 800nm because, in the NIR range, the sensitivity of silicon-based-arrays decreases rapidly with the wavelength. The filter should have a steep edge at about 800nm and, below 800nm, there should preferably be no radiation at all or at least no disturbing emission. Red light at the front of a car is absolutely not tolerable but a small emission of white light is rather a feature than a bug. This contribution describes a source of NIR radiation with a main emission in the wavelenght range of 800-1100nm. Since automotive halogen lamp technology is used, this source will be called a 'NIR lamp', although this is strictly speaking a contradiction in itself. Often, the use of IR diodes as an automotive night vision illuminator is suggested. By the data provided in this contribution the reader may calculate, how many of them it takes to replace a single NIR lamp and what they would cost. More application benefits are due to the constant and continuous radiation which is the perfect supplement to the car's passing beam.
Halogen lamps for active night vision
Halogenlampen für aktive Nachtsichtsysteme
2005
10 Seiten, 8 Bilder, 2 Tabellen, 1 Quelle
Conference paper
English
Halogen and Incandescence Lamps
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