the pelt man Posted January 18, 2007 Report Share Posted January 18, 2007 Hi Pin Take a look at this PDF file it might shed some light on the problem (pun intended) http://www.optics.arizona.edu/nofziger/OPT...e%201%20JMP.pdf As it shows the Human eye see's light from 380nm < 750nm, 750nm being around the start of IR wavelength, (page 20 on the PDF). The higher you go through the IR wavelength the light then turns to heat, eg using heat camara's. If the Rabbits eyes see similar to the human eye then i would conclude that the Tapetum Lucidum would only reflect up to a certain nm because going higher it would be reflecting heat (thermal radiation) & burn its own eyes out, 1350nm's is when you reach the point of thermal radiation & is in the wavelength that plod use there thermal imaging camaras. The reason that rabbits dont run so much when using a red filter on a lamp is because the light wavelength is getting close to what it can't see. We need to find the wavelength that it can't see at the IR end but is enough to reflect off the Tapetum Lucidum, with the lowest nm possable, to obtain max reflection & distance with the IR light sorce. What is the nm of the filter you bought, what will be the nm of the gells that you have ordered ? PELTMAN Quote Link to comment Share on other sites More sharing options...
pin Posted January 18, 2007 Author Report Share Posted January 18, 2007 When I looked into this I found out there are different forms of Tapetum Lucidum, in fact in a lot of animals its not actually called that.. I have not managed to find out for definite exactly what rabbits have, or exactly what wavelengths they can reflect, however via practical experiment we can make an educated guess :- Since normal lamps which emit a perceived white light (which is all the wavelengths together) shine up their eyes and the illuminator from the NV itself also picks out their eyes ( roughly in the 700-750nm range), and we know red light (about 650nm) again picks them out - its fair to assume that its the close to visible range which can be reflected. As far as I know the sheet I have is blocking the "near" IR and allowing the further IR through. Roughly with a pass filter of 800nm+. If we assume the above is correct then we know that we need something which at least allows a good portion of light in the 700nm region through, and blocks a good portion of visible red light too. Via experiment last night I noticed that the IR lamp would not light the eyes alone, but in combination with the built-in on the NV, it made them light appreciably brighter. This tells me that there is a component to the light coming through the IR lamp which is extremely close to what we want, but there isn't enough of it. The filter gels I am expecting are apparently transparent to IR, that is they allow it all through. If this is true then the light we want will be present, its simply a matter of how much visible light they can block. Quote Link to comment Share on other sites More sharing options...
pin Posted January 18, 2007 Author Report Share Posted January 18, 2007 Spoke to a chap called Ashley at cobra optics (who supplied the sheet) and he confirmed that the sheet is passing 830nm +/- 10%. He also confirmed that the illuminator built into the NV was cheap and was probably leaking quite a bit below and above that figure. I think its the small amount below 830nm which is doing it, the closer portion to visible. Bah, I want this to work without all this bloody physics, the filter sheet won't be here for a week, annoying Quote Link to comment Share on other sites More sharing options...
the pelt man Posted January 18, 2007 Report Share Posted January 18, 2007 He is right that the NV is leaking light in the lower nm, when you look at the front of the NV when the IR is switched on you can see red light so it is not blocking all visable light. Just need to find the lowest nm without spooking bunny Hurry up & sort it out Pin PELTMAN Quote Link to comment Share on other sites More sharing options...
pin Posted January 18, 2007 Author Report Share Posted January 18, 2007 Well, I suggest we lab it, I can provide the bunny Quote Link to comment Share on other sites More sharing options...
the pelt man Posted January 18, 2007 Report Share Posted January 18, 2007 Well, I suggest we lab it, I can provide the bunny "ANIMAL TESTING" They'll dig up your Granny PELTMAN Quote Link to comment Share on other sites More sharing options...
pin Posted January 18, 2007 Author Report Share Posted January 18, 2007 I am annoyed I can't sort this out now, but until the new material shows up there isn't a lot I can do. I am fairly certain it will work, if like it says it passes all IR through it. Quote Link to comment Share on other sites More sharing options...
the pelt man Posted January 18, 2007 Report Share Posted January 18, 2007 I am annoyed I can't sort this out now, but until the new material shows up there isn't a lot I can do. I am fairly certain it will work, if like it says it passes all IR through it. Just saw on a photo site, Buy 120mm Slide Film from photo shop, get them to develope it as is (ignore the blank look on there faces) now you have a cheap IR filter at a fraction of the cost PELTMAN Quote Link to comment Share on other sites More sharing options...
pin Posted January 18, 2007 Author Report Share Posted January 18, 2007 I heard about that too, but not sure how much IR they pass... Quote Link to comment Share on other sites More sharing options...
Ferretboy111 Posted January 18, 2007 Report Share Posted January 18, 2007 Right im confused about the whole thing, if too many wavelengths stuff is passing through the filter cant you just dull the filter down with something? like a thin laquer of some sorts? Alex Quote Link to comment Share on other sites More sharing options...
Country_est Posted January 18, 2007 Report Share Posted January 18, 2007 I've got a lab you can use to test the bunny. See avatar for details Seriously though guy keep up the good work as I have a couple of 2mil torches from B&Q £10 stuff that could be easliy converted with a scope as well. Cheers Trev Quote Link to comment Share on other sites More sharing options...
pin Posted January 18, 2007 Author Report Share Posted January 18, 2007 Right im confused about the whole thing, if too many wavelengths stuff is passing through the filter cant you just dull the filter down with something? like a thin laquer of some sorts? Alex Nah, the light getting through is the wrong sort, only different material for the filter itself will work - shame it will be a week coming but there you are Quote Link to comment Share on other sites More sharing options...
markbivvy Posted January 18, 2007 Report Share Posted January 18, 2007 Buy 120mm Slide Film from photo shop hi pin. you could try the above , nip into town in the morning and be back in the field at night. Quote Link to comment Share on other sites More sharing options...
the pelt man Posted January 19, 2007 Report Share Posted January 19, 2007 I heard about that too, but not sure how much IR they pass... I will be trying this today Lets hope it dose the trick PELTMAN Quote Link to comment Share on other sites More sharing options...
pin Posted January 19, 2007 Author Report Share Posted January 19, 2007 I'd wait until tonight if I were you Quote Link to comment Share on other sites More sharing options...
the pelt man Posted January 19, 2007 Report Share Posted January 19, 2007 I'd wait until tonight if I were you B) Quote Link to comment Share on other sites More sharing options...
pin Posted January 19, 2007 Author Report Share Posted January 19, 2007 So, what's the verdict? Quote Link to comment Share on other sites More sharing options...
pestbry Posted January 19, 2007 Report Share Posted January 19, 2007 So, what's the verdict? look at this pin http://cgi.ebay.co.uk/Infrared-Lamp-IR-X-R...tem280072047294 Quote Link to comment Share on other sites More sharing options...
pin Posted January 19, 2007 Author Report Share Posted January 19, 2007 Yep, exactly what I should have in a few days when I get filter material that's suitable. Been interesting to look into all this, at least I know why its not working for what I want Quote Link to comment Share on other sites More sharing options...
the pelt man Posted January 20, 2007 Report Share Posted January 20, 2007 So, what's the verdict? Find Me someone that sells/devlopes the stuff & i'll find out I think i will have to buy it from E-bay but still need to find where i can get it prosessed. I've asked the E-bay seller of that IR before i start to bid on the lamp, dose it reflect animals eyes & what is the IR's filter nm value lets hope he don't work out that we are trying to make our own PELTMAN Quote Link to comment Share on other sites More sharing options...
kip270 Posted January 20, 2007 Report Share Posted January 20, 2007 http://www.cluson.co.uk/productsMain.aspx?CI_ID=34 These do a IR filter for the Clulite Quote Link to comment Share on other sites More sharing options...
Hunter_zero Posted January 21, 2007 Report Share Posted January 21, 2007 http://www.cluson.co.uk/productsMain.aspx?CI_ID=34 These do a IR filter for the Clulite Hi all! I've not read all the post (too many) but are you trying to make an IR light source? They are easy to make! I purchased 10'x4' of IR perspex (£150) and that makes a lot of lamps! In fact ten years on, I still have IR perspex here All you have to do, is replace the clear filter with an IR filter BUT you must make sure that you can focus the beam or you'll not have any real luck! John Quote Link to comment Share on other sites More sharing options...
stevethevanman Posted January 21, 2007 Report Share Posted January 21, 2007 You said you tried it on your pet rabbit, well he has some genetic rabbit thing were he does not reflect IR perhaps...... Quote Link to comment Share on other sites More sharing options...
kip270 Posted January 21, 2007 Report Share Posted January 21, 2007 This may be of some help http://www.nightvisionforums.com/viewforum.php?f=9 Quote Link to comment Share on other sites More sharing options...
pin Posted January 21, 2007 Author Report Share Posted January 21, 2007 Cheers kip, some useful posts on there. Hoping the new material will be with me this coming week Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.