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Discussion Starter · #1 ·
I've been messing around with the concept of using LEDs to provide the "dawn" and "dusk" for my tank. Another fun application could be to use a couple of blue shifted LEDs to simulate a little bit of moonlight or to use LEDs within the enclosure to highlight a water feature, plant, etc. with the overhead lights off. Also, given the relative pain involved in getting UV to plants, frogs, etc., I have thought about trying to find a UV LED and drilling through regular acrylic and flush mounting the UV LEDs so that there isn't anything between them and the enclosure. I don't think heat would be an issue and can only foresee a problem with eye damage if the frogs hung upside down very close to the source. If this is likely then there might be a way to offset the LEDs. Also, I think a UV LED probably will probably outlast the 1 year UV lifespan of your average tube or CF.

The problem is that would probably take some good calculations to figure out what the right intensity is, and some information about which wavelenghts of what UV are the ones necessary since UV LEDs emit UV in a much narrower band. The construct the LED assembly would also require some tweaking to ensure that the intensities were at the right level. Has anybody thought about doing this?

Marcos
 

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Discussion Starter · #5 ·
Good to know. Look forward to seeing some of those scientific UVB LEDs make their way to market someday.

Regarding simulating moonlight, I have seen 420nm referenced quite a bit, and I think with good reason. While the moon is in fact reflecting sunlight as mentioned, the difference in intensity allows the rods to play a more dominant role in night vision. From what I understand, the peak sensitivity of rods is around 500nm and its the rods' production of rhodopsin that allows us to have night vision. There are certain lighting intensities (daytime conditions) that inhibit rhodopsin production which is a major reason why it takes a while for your eyes to adjust to the darkness.

For these reasons, I think the 420nm would probably give a better representation of nightime by simulating night vision (scotopic vision) or twilight vision (mesopic vision) under day vision conditions (photopic vision) rather than dim white LEDs. There is also something about those wavelenghts that allow them to land more on the fovea and create less eyestrain at night. That is supposedly (don't have a reference) the reason military aircraft moved from red lights to blue/green lights, NVGs are blue/green (except for the newer yellow tinted ones) and most of your car dashboards are a variation on this theme.

I was a Blackhawk pilot in my prior life and we had to learn all sorts of stuff about night vision. I'm a little rusty so don't quote me :)

Here are some good sites:
http://www.narcap.org/TheEyeandNightVision.htm
http://www.syz.com/rasc/lp/lightandtheeye.html
http://www.chemsoc.org/exemplarchem/ent ... dopsin.htm

Marcos
 
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