Ah, that would explain why UV lighting works so well then... > -----Original Message----- > From: pic microcontroller discussion list > [mailto:PICLIST@mitvma.mit.edu] On Behalf Of Eoin Ross > Sent: 14 March 2002 17:29 > To: PICLIST@mitvma.mit.edu > Subject: [OT]: LED sources... > > > For brake/stop light on cars there is a good reason - when > you are following a car it would be ideal if you're night > vision was not affected by the lights in front of you - red > light is the least destructive to night vision. > > Earlier in the topic someone suggested that this was due to > the iris being less responsive to red than other colours. I > disagree based on what I remember hearing seeing (rather > vaguely too I might add) THe cells in the retina are > sensitive to different wavelengths of light (colour) - the > one responsible for night vision cannot sense colour, I > believe they are more sensitive to purple - which would > account for yellow and blue affecting night vision more than > red as red is further away from the cells centre frequency. > Night vision uses a certain chemical/pigment which is "used > up" in bright light - it takes a little time for it to build > up again. Notice how it take a little while for eyes to "get > used to the dark"? > > I have to concur on wondering why red is used for stop signs > etc - yellow would seem to make more sense as yellow > penetrates fog etc better - and is a brighter colour. > > >>> picdude@AVN-TECH.COM 03/14/02 11:58AM >>> > > If eyes are least sensitive to red, then I wonder why its > used in most alerting situations (brake lights, stop signs, > etc).... hmmm? > > -- > http://www.piclist.com hint: The list server can filter out > subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics ***************************************************************** This email has been checked by the altohiway e-Sweeper Service ***************************************************************** -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.