From: Tom Hubin (thubin@clark.net) Subject: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/03/31 Hello, I was looking into using red backlighting for a 3 digit LCD to be used outdoors, sometimes at night. Somebody suggested using "night vision green". They said that the military had done some stidies and came up with a green that does not hurt your night vision. Any info on this? Any particular red LED wavelength that I should be using for best viewing with least damage to night vision? Current consumption is not a major consideration. This will be run from a large +12vdc battery along with a lot of other electronics. The unit will not be repairable so cost is a factor. Tom Hubin thubin@clark.net From: pyromaniac_guy@hotmail.com (pyromaniac_guy@hotmail.com) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/03/31 On Wed, 31 Mar 1999 15:48:03 -0800, Tom Hubin wrote: >Hello, > >I was looking into using red backlighting for a 3 digit LCD to be used >outdoors, sometimes at night. Somebody suggested using "night vision >green". They said that the military had done some stidies and came up >with a green that does not hurt your night vision. Any info on this? > >Any particular red LED wavelength that I should be using for best >viewing with least damage to night vision? Current consumption is not a >major consideration. This will be run from a large +12vdc battery along >with a lot of other electronics. The unit will not be repairable so cost >is a factor. > >Tom Hubin >thubin@clark.net Tom, to protect your night vision, use a color led that the eye does not have a high relative intensity reponse to, ie the 'reder' the better, try 660nm or so.. as far as green goes, I can't think of any way, of doing it... all the green colors I know of are pretty close to the peak of the eye's response curve... you can always try a VERY low intensity green led, as opposed the the red... just be sure that the light out put is very low, that's the only way I can think of ruining your night vision with green led's pyroguy From: Gregory L. Hansen (glhansen@steel.ucs.indiana.edu) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/01 In article <7du5av$o8r$1@news-1.news.gte.net>, wrote: >Tom, >to protect your night vision, use a color led that the eye does not >have a high relative intensity reponse to, ie the 'reder' the better, >try 660nm or so.. as far as green goes, I can't think of any way, of >doing it... all the green colors I know of are pretty close to the >peak of the eye's response curve... you can always try a VERY low Maybe that's the secret. Color is in your cones, night vision is in your rods. If you use a color that's at the peak of the eye's response curve you can do it with less light, which is a smaller hit to the rods. -- The opinions expressed herein are my own and do not represent those of NASA. Hell, I don't even work for NASA. From: Charles W. Shults III (aichip@gdi.net) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/03/31 Tom Hubin wrote: > > Hello, > > I was looking into using red backlighting for a 3 digit LCD to be used > outdoors, sometimes at night. Somebody suggested using "night vision > green". They said that the military had done some stidies and came up > with a green that does not hurt your night vision. Any info on this? > > Any particular red LED wavelength that I should be using for best > viewing with least damage to night vision? Current consumption is not a > major consideration. This will be run from a large +12vdc battery along > with a lot of other electronics. The unit will not be repairable so cost > is a factor. > > Tom Hubin > thubin@clark.net Sorry, incorrect. Many of the displays in modern electronics are using green LEDs because of their compatibility with ANVIS goggles. The green is not good for night vision. Red light is the only way to save your night vision, as it is less likely to destroy the rhodopsin molecules that night vision requires. Red light is of a much lower energy than green, and many military night vision systems of old used green phosphor because the eye was much more sensitive to green light than red. Cheers! Chip Shults From: KillaKoala (steve2468@hotmail.com) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/02 Tom Hubin wrote in message <3702B433.46A6@clark.net>... >Hello, > >I was looking into using red backlighting for a 3 digit LCD to be used >outdoors, sometimes at night. Somebody suggested using "night vision >green". They said that the military had done some stidies and came up >with a green that does not hurt your night vision. Any info on this? If this is the case then why do warships have red lighting at night? From: Tom Hubin (thubin@clark.net) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/02 KillaKoala wrote: > > Tom Hubin wrote in message <3702B433.46A6@clark.net>... > >Hello, > > > >I was looking into using red backlighting for a 3 digit LCD to be used > >outdoors, sometimes at night. Somebody suggested using "night vision > >green". They said that the military had done some stidies and came up > >with a green that does not hurt your night vision. Any info on this? > > If this is the case then why do warships have red lighting at night? It pays to ask questions. I have a little more info on "night vision green". It apparently gets its name because that wavelength stimulates night vision goggles more efficiently. So it appears that it has nothing to do with human night vision. This is still hearsay to me but it makes more sense now than it did yesterday. Although I am still getting tidbits about an amber color that does little harm to human night vision. The info is vague though. I would like to see a recent study or report of some sort. Tom Hubin thubin@clark.net From: Skywise (spamless@cwixmail.com) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/02 KillaKoala wrote: > Tom Hubin wrote in message <3702B433.46A6@clark.net>... > >Hello, > > > >I was looking into using red backlighting for a 3 digit LCD to be used > >outdoors, sometimes at night. Somebody suggested using "night vision > >green". They said that the military had done some stidies and came up > >with a green that does not hurt your night vision. Any info on this? > > If this is the case then why do warships have red lighting at night? Actaully, they maybe moving away from red lighting. More than once I have seen the interiors of control rooms on ships such as the Aegis cruisers that are illuminated in blue. -- Skywise for email replies, please change "spamless" in my address to my nickname From: Ray Vanlandingham (rayvan@javanet.com) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/04 Skywise wrote in message <37048060.1C516DFC@cwixmail.com>... >Actaully, they maybe moving away from red lighting. More than once I have >seen the interiors of control rooms on ships such as the Aegis cruisers >that are illuminated in blue. I don't know about surface ships, but submarines use red light when putting up a periscope or on the surface...there is actually a procedure to 'rig for red', as well as red filters in the windows of doors to adjacent spaces. From: Geoff Harwood (geoff.harwood.DeleteThis@freenet.co.uk) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/04 On Fri, 02 Apr 1999 08:30:02 GMT, Skywise wrote: >Actaully, they maybe moving away from red lighting. More than once I have >seen the interiors of control rooms on ships such as the Aegis cruisers >that are illuminated in blue. > > > >KillaKoala wrote: > >> Tom Hubin wrote in message <3702B433.46A6@clark.net>... >> >Hello, >> > >> >I was looking into using red backlighting for a 3 digit LCD to be used >> >outdoors, sometimes at night. Somebody suggested using "night vision >> >green". They said that the military had done some stidies and came up >> >with a green that does not hurt your night vision. Any info on this? >> >> If this is the case then why do warships have red lighting at night? > >-- >Skywise > >for email replies, please change "spamless" in my address to my nickname I worked for many years for a well known photographic materials manufacturer and part of my job was designing darkroom lighting. So I got to know a bit about dark adaptation. Now I spend some time navigating a small boat in the crowded waters of the Solent and English Channel, often in the dark. True dark adaptation is achieved after about 20 minutes in very low levels of illumination (less than full moonlight) when only the rods are in use. These have a peak sensitivity in the blue/green and it is true that a dim red light (the longer the wavelength the better) would do the least damage to that regime of vision (scotopic). However scotopic vision, while enabling you to avoid cowpats when walking across a field in the moonlight, has neither the resolution or the colour discrimination to be of great use for working or navigating. For these purposes the cones are required and they are high resolution and of three kinds sensitive to red, green or blue, each with its own separate dark adaptation. Traditionally a red light is provided for the navigator but I believe this to be counterproductive for two reasons. First, the charts (British Admiralty) show navigation mark lights in magenta which is practically invisible in red light and secondly, the lights which must be picked out at the earliest moment are the red ones (vessels approaching from the starboard side). If you've recently had your head down in the red light of the chart table, your red sensitivity is much reduced. What is really required at the chart table is a minimum level of "white" light, just enough to see detail in the chart with a magnifier. It would be slightly helpful to bias the spectral balance towards the blue so a dimmed filament lamp would be less suitable than one of the new "white" LEDs which are somewhat that way inclined. I also posted this reply to a similar thread in sci.optics yesterday Geoff Harwood From: Ran (ran@netgate.net) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/06 In <37079054.5169547@news.freenet.co.uk>, geoff.harwood.DeleteThis@freenet.co.uk (Geoff Harwood) writes: >However scotopic vision, while enabling you to avoid cowpats when >walking across a field in the moonlight, has neither the resolution or >the colour discrimination to be of great use for working or >navigating. I think this is the key: the red illumination allows people to move around without bumping into things, while not compromising night vision *that's needed for a different purpose*. I.e., everyone on the bridge sacrifices a little "visual productivity" so that the people who need to look through pericopes/binoculars/etc. can get the most out of their eyes. >What is really required at the chart table is a minimum level of >"white" light This is certainly true if the navigator doesn't also have to be a "spotter". I think the optimum mix of light is likely to be different for, e.g., an astronomer or a pilot who alternates between the chart and the "real world". My guess would be: mostly the "traditional" red, with small amounts of shorter wavelengths added to allow for seeing some details without unduly compromising night vision. It would be especially important to avoid wavelengths and levels that would trigger pupil constriction. For an LED-based lamp, I'm thinking a hefty red diode, with some green added to read black-and-white, and maybe an amber/yellow to improve the readability of things printed in multiple colors. My guess is that adding blue to the mix is more likely to cause a pupillary response, but my education in this area is limited to snippets picked up here and there over the years, so I could well be wrong. I'd be most interested in hearing from someone who's done some actual research, or even gotten some formal training, in this area. Ran From: Ray Vanlandingham (rot13-for-email.enlina@wninarg.pbz.invalid) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/07 On Tue, 06 Apr 1999 07:25:40 GMT, ran@netgate.net (Ran) wrote: >In <37079054.5169547@news.freenet.co.uk>, geoff.harwood.DeleteThis@freenet.co.uk (Geoff Harwood) writes: >I.e., everyone on the bridge sacrifices a little "visual productivity" >so that the people who need to look through pericopes/binoculars/etc. >can get the most out of their eyes. Actually, modern submarine periscopes have built-in 'night vision' devices. Of more concern is reflecting the ambient light from the control room out the periscope and aiming it at the target you are observing. >>What is really required at the chart table is a minimum level of >>"white" light For the only chart that would be particularly relevant when tracking targets at PD, all that is required it to mark the spot where a small 'x' is reflected from underneath the paper. Ambient light isn't a major concern. ------------ Ray Vanlandingham From: Thomas Jaworowski (noone@no.spam.edu) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/05 I have been told once by a physics professor that the reason that night vision goggles use green is that the human eye can differentiate more shades of green than any other color. He said that many biologists attribute this with our evolution and that perhaps once we used green to be able to tell what plants were good to eat and which ones weren't. Now we can use it to hunt in the dark. Thomas Jaworowski EE undergrad From: Erik Max Francis (max@alcyone.com) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/05 Thomas Jaworowski wrote: > I have been told once by a physics professor that the reason that > night > vision goggles use green is that the human eye can differentiate more > shades > of green than any other color. He said that many biologists attribute > this > with our evolution and that perhaps once we used green to be able to > tell > what plants were good to eat and which ones weren't. I haven't heard of that, but the Sun's frequencies peak at green, so it makes sense that we would see best at around that peak frequency. Also, it's awfully convenient of chlorophyll (and other such molecules) absorb energy around the peak frequency, in order to maximize the amount of available energy available for photosynthesis. That is, it seems more reasonable to me that both items (humans see green best; plants are green) are effects of the same cause (sunlight peaks in green), rather than one causing the other. > Now we can use it to hunt in the dark. Although we rarely use them to hunt for food. -- Erik Max Francis / email max@alcyone.com / whois mf303 / icq 16063900 Alcyone Systems / irc maxxon (efnet) / finger max@members.alcyone.com San Jose, CA / languages En, Eo / web http://www.alcyone.com/max/ USA / icbm 37 20 07 N 121 53 38 W / &tSftDotIotE \ / To know oneself, one should assert oneself. / Albert Camus Message 14 in thread From: Jim Mansfield (mansfield@ibd.nrc.ca) Subject: Re: Night Vision Green? View this article only Newsgroups: sci.optics, sci.physics Date: 1999/04/05 In article <37091C73.7E228490@alcyone.com>, Erik Max Francis wrote: >Thomas Jaworowski wrote: [snip night vison goggles being green - I haven't a clue why they are] >I haven't heard of that, but the Sun's frequencies peak at green, so it >makes sense that we would see best at around that peak frequency. Also, >it's awfully convenient of chlorophyll (and other such molecules) absorb >energy around the peak frequency, in order to maximize the amount of >available energy available for photosynthesis. Doesn't there seem to be something conflicting about plant leaves _looking_ green (ie, reflecting green light) and their absorbing energy at the Sun's peak frequency of green? Chlorophyll has absorption maxima in the blue and, to a lesser extent, in the red. -Jim -- Jim Mansfield Internet: Jim.Mansfield@nrc.ca National Research Council of Canada Phone: (204) 984-5191 Institute for Biodiagnostics Fax: (204) 984-5472 http://www.ibd.nrc.ca/~mansfield/ From: Marcangelo Puccio (mpuccio@leland.stanford.edu) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/05 Jim Mansfield wrote: > In article <37091C73.7E228490@alcyone.com>, > Erik Max Francis wrote: > >Thomas Jaworowski wrote: > > [snip night vison goggles being green - I haven't a clue why they are] > > >I haven't heard of that, but the Sun's frequencies peak at green, so it > >makes sense that we would see best at around that peak frequency. Also, > >it's awfully convenient of chlorophyll (and other such molecules) absorb > >energy around the peak frequency, in order to maximize the amount of > >available energy available for photosynthesis. > > Doesn't there seem to be something conflicting about plant leaves _looking_ > green (ie, reflecting green light) and their absorbing energy at the > Sun's peak frequency of green? Chlorophyll has absorption maxima in > the blue and, to a lesser extent, in the red. > > -Jim > > -- > Jim Mansfield Internet: Jim.Mansfield@nrc.ca > National Research Council of Canada Phone: (204) 984-5191 > Institute for Biodiagnostics Fax: (204) 984-5472 > http://www.ibd.nrc.ca/~mansfield/ Yes - you are right. Plants photosynthesize poorly at best if illuminated by light at around 530 nm. The following numbers are rough, but peak absorption in the red end is at around 650 nm for Chlorophyll-a and at around 670-680 for Chlorophyll-b. Peaks in the blue end are at around 440 and 460, respectively, with absorption minima between 500 and 600 nm. Some plants have 'accessory pigments' that are able to absorb light pretty well in the 500 nm range (i.e., carotenoid piments like beta carotene). These form part of an 'antenna complex' that channels energy from these other wavelengths to the chlrorophyll molecules that are the core of the photosystems. Some aquatic 'plants' (algae, actually) have radically different absorptions that reflect the fact that certain wavelengths of light are absorbed or reflected from sea water (i.e., red and golden algae or 'seaweeds'). Not that this is a photobiology newsgroup... just had to comment! -Marco From: Charles W. Shults III (aichip@gdi.net) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/06 Erik Max Francis wrote: > > Thomas Jaworowski wrote: > > > I have been told once by a physics professor that the reason that > > night > > vision goggles use green is that the human eye can differentiate more > > shades > > of green than any other color. He said that many biologists attribute > > this > > with our evolution and that perhaps once we used green to be able to > > tell > > what plants were good to eat and which ones weren't. > > I haven't heard of that, but the Sun's frequencies peak at green, so it > makes sense that we would see best at around that peak frequency. Also, > it's awfully convenient of chlorophyll (and other such molecules) absorb > energy around the peak frequency, in order to maximize the amount of > available energy available for photosynthesis. Oops! Chlorophyl _reflects_ green, not absorbs. It works best with red wavelengths... Cheers! Chip Shults From: Kirk Melby (kirk.melby@lightspeed.wa.com) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/06 Thomas Jaworowski wrote in message <7e9cpq$1udo@r02n01.cac.psu.edu>... >I have been told once by a physics professor that the reason that night >vision goggles use green is that the human eye can differentiate more shades >of green than any other color. He said that many biologists attribute this >with our evolution and that perhaps once we used green to be able to tell >what plants were good to eat and which ones weren't. > >Now we can use it to hunt in the dark. > >Thomas Jaworowski >EE undergrad Yes. Some one finally got it right. The eye can perceive more shades of green than any other color. Night vision goggle displays are monochromatic, so green is used to allow you to better differentiate subtle deference's between objects. Red is the best choice for keeping your eyes dark adapted. From: Willem-Jan Markerink (w.j.markerink@a1.nl) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/08 In article <7edqht$rm2$1@brokaw.wa.com>, "Kirk Melby" wrote: >Thomas Jaworowski wrote in message <7e9cpq$1udo@r02n01.cac.psu.edu>... >>I have been told once by a physics professor that the reason that night >>vision goggles use green is that the human eye can differentiate more shades >>of green than any other color. He said that many biologists attribute this >>with our evolution and that perhaps once we used green to be able to tell >>what plants were good to eat and which ones weren't. >> >>Now we can use it to hunt in the dark. >> >>Thomas Jaworowski >>EE undergrad >Yes. Some one finally got it right. The eye can perceive more shades of >green than any other color. Night vision goggle displays are monochromatic, >so green is used to allow you to better differentiate subtle deference's >between objects. Is this closely related to the fact that green (555nm) is also the most efficient color for the human eye? IOW: given a certain luminance (not color-depending, right?), the human eye can see more shades of green *because* green appears brighter, and because of which subtle differences are more easy to spot? >Red is the best choice for keeping your eyes dark adapted. > But *why* exactly the latter? Because the rods (night vision, right?) indeed have a red-deficiency compared to cones? So you a) don't spoil your own night adaptation, and b) the enemy, staring in the dark, has more trouble spotting red lights than any other color. -- Bye, Willem-Jan Markerink The desire to understand is sometimes far less intelligent than the inability to understand [note: 'a-one' & 'en-el'!] From: Paul Richards (Paul@dunvegan1.demon.co.uk) Subject: Re: Night Vision Green? Newsgroups: sci.optics, sci.physics Date: 1999/04/10 Willem-Jan Markerink writes, >>Red is the best choice for keeping your eyes dark adapted. >> > >But *why* exactly the latter? >Because the rods (night vision, right?) indeed have a red-deficiency >compared to cones? >So you a) don't spoil your own night adaptation, and b) the enemy, staring >in the dark, has more trouble spotting red lights than any other color. Say the cones are split up like this: 40% green, 33% blue and 26%red. If we use red lights then 26% of our cones are at daytime levels. If we use green lights then 40% of our cones are at daytime levels. Therefor by using red lights more of our retina is at night time levels. I completely made all that up so feel free to correct me... -- Paul Richards (aka. Pauldoo) EMAIL paul@dunvegan1.demon.co.uk HTTP www.dunvegan1.demon.co.uk/paul/ ICQ# 14106503 Subject: Re: flits in de snoet.... From: Jasper Janssen Date: Sat, 14 Feb 2004 20:44:21 GMT Newsgroups: nl.auto On Sat, 14 Feb 2004 10:40:17 +0100, "Nagel" wrote: >Wat een onzin, die flits duurt maar 1/1000 ste van een seconde en >dat is te kort om je ogen te verblinden alleen je hersenen registreren >de flits wel. Je praat poep. Ga maar eens met een fotoflitser in je ogen schieten terwijl je ogen goed donker-geadapteerd zijn. Zelfs indirekt over de muur verblind je dan nog. Ook een fotoflitser triggert de pupil contractie (zoals bijvoorbeeld gebruikt wordt bij red-eye-reduction, eerst een paar hele lage intensiteit flitsjes, dan gaat je pupil dicht en als er dan vol geflitst wordt voor de foto heb je geen rood oog omdat er door die dichte pupil niet zoveel licht reflecteert van je netvlies af. Daarnaast heb je de nachtzicht adaptatie, als er weinig licht is, dan worden er meer lichtgevoelige moleculen gemaakt (ieder molekuul reageert op 1 foton, dus als er meer molekulen zijn is de kans groter dat die paar fotonen er ook een raken), maar de flits gebruikt in een keer bijna alle lichtgevoelige molekulen op, en het duurt dan weer enige minuten voor ze weer op peil komen. Jasper