According to the Vienna Convention concerning automotive lighting and the ECE-regulation No.48 'No red light which could give rise confusion shall be emitted from a (head)lamp as defined in paragraph 2.7 in forward direction'. Moreover, in clause 5.10.1 the regulation refers to 'the visibility of red light towards the front'. On the other hand there are more and more night-vision systems which use infrared radiation. In active systems the near infrared part requires an active illumination of the scene in front of the car, comparable to a driving beam. Infrared radiation is used to avoid glaring of oncoming drivers, but the camera systems have the maximum sensitivity in the still 'visible' edge of the spectrum. Therefore it is useful to have the maximum of the emitting IR-radiation near the visible edge of the V(lambda)-function; but it is not clear where exactly is the border between visible an non visible radiation at the red end of the spectrum. Traditionally we speak of the visible radiation between 380 nm and 780 nm and most detectors, and especially color detectors, will only respond in this region. The human eye on the other hand has a specific sensitivity up to 1100 nm. The paper discusses the problems related to special measurement procedures for near infrared illumination systems. There exist three different possibilities for producing NIR-radiation in front of a car: halogen filament lamps with special filters, NIR-LED's and NIR-lasers. When making measurements on NIR headlamps one should be aware that the eye can detect radiation beyond 780 nm. The sensitivity function is already known and the detector should have the expanded sensitivity function in order to avoid confusion, when the eye will detect radiation where the sensor would not. The other question is the maximum permissible value for the red light to the front.
The photometry of near infrared headlamps
Die Photometrie der Nahinfrarotscheinwerfer
2005
6 Seiten, 4 Bilder, 1 Tabelle, 2 Quellen
Conference paper
English
Infrared headlamps for active night-vision systems
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