Nichia 365nm UV Light offerings (NEW 5-12-17)

[derangboy]

Re: Nichia 365nm Light offerings

"Transitions" lenses are activated by UV light as explained on their website. I know for sure that a 405nm source will darken them in a hurry.

 

[McGizmo]

Re: Nichia 365nm Light offerings

...
As for the second two pictures, all I can say is in real life the emitter appears only dimly lit, nothing like the blinding electric-blue light you see in the photos, so I'm going to go ahead and conclude my camera IS seeing the UV directly, and misinterpreting it as visible blue light. The dramatic decrease in brightness when I interpose my glasses between the emitter and the camera shows a substantial portion of the UV is being blocked by my glasses.

A common filter suggested to a SLR package is a UV filter. Typically this was an opportunity for the camera store to make a bit more $ on the sale as well as offering the buyer a protective sacrificial piece to protect the lens but I suspect there is legitimate justification for adding a UV blocking filter to the camera. It is my impression that some of the CCD's in the digital cameras do have some IR and UV blocking done by a glass filter above the CCD but I think this can vary significantly. That is to say that I believe many of the cameras do see the UV light and it does register visibly in the resulting image.

I think we have some camera experts among us who could shed more light on this if they elected to come forward or even saw this thread.

I did a google on photochromic and from HERE, I quote:

Photochromic lenses have millions of molecules of substances such as silver chloride or silver halide embedded in them. The molecules are transparent to visible light in the absence of UV light, which is normal for artificial lighting. But when exposed to UV rays, as in direct sunlight, the molecules undergo a chemical process that causes them to change shape. The new molecular structure absorbs portions of the visible light, causing the lenses to darken. The number of molecules that change shape varies with the intensity of the UV rays.

What may vary or may be of import is specifically what bands of UV are responsible for the change and what portion of UV if any is passed with the typical photochromic window or lens material. It does appear that fyrstormer's glasses don't pass the 365nm generated by the LED and in addition, they are not activated in their darkening feature by this band of UV. :shrug:

Since we can't see UV we really need an instrument that does and can measure it to identify what materials block as well as pass this light on. The lack of fluorescence in the white paper in the image above does seem to be an indication of UV blocking in the narrow 365 band that the Nichia does produce.

I would guess that ideally the lenses on such glasses would simply block all UV light and use the near UV light as a trigger for darkening. A car windshield I believe blocks most UV and you would want the light passed through the windshield to be able to activate your sunglasses based on the intensity, I would imagine. Interesting stuff!

 

[Bass]

Re: Nichia 365nm Light offerings

frystormer - thanks again for all the photos. Your glasses are definitely cutting out the 365nm UV from the LED, that can be clearly seen from your images. Your camera has done a good job picking this up!

I am by no means an expert, or any authority on the subject but in answer to Don's post below, my understanding is that UV filters are only really useful for film photography. They have very little, if any use in digital, apart from to offer protection. In fact, digital sensors (CCD & CMOS) are susceptible to Infrared, not UV. The filter above the sensor on digital SLR's can be removed by a specialist to allow the camera to be used for IR photography. I believe CCD sensors are more susceptible to IR than CMOS and as such make better conversions for IR photography.

UV light increases in higher altitudes. UV light renders as a blue haze / mist on daylight balanced film. Film renders UV as blue, so there was a real need for a UV filter in the film days. I am surprised your camera (Casio EX-Z700 - from your EXIF data) is able to reproduce the UV so well. :thinking:

I agree it is interesting that your glasses clearly block the UV light but don't darken. I did a Google for 'transitional lenses' and they say they block all UVA (which would include 365nm) and UVB. The lenses must only darken above 380nm (visible spectrum) - clever stuff.

Going back to my original question - prescription glasses good enough for use with the 365nm Nichia, or advisable to use something stronger (as per earlier posts on this thread)?

Thanks.

 

[Codeman]

Re: Nichia 365nm Light offerings

Unfortunately, the fact that his hand is clearly lit also means that reflected visible light is skewing the appearance of both the paper and the shadow. Try taking the photo in a completely dark room where the only light source is your mule and let us see that. Unless the shadow was solid black in such a photo with correct exposure, then UV may still be getting through. Even then, the results would be questionable, since consumer cameras are designed to properly expose visible light only. If they did respond to UV in a significant way, the resulting images would not look the same as what our eyes saw the scene as.

If there is even a slight chance of a highly reflective surface throwing some 365nm waves back at me, I wear a pair of UV-specific safety glasses. Even rated at blocking 99.9% of UVA/UVB, the 0.1% that gets through can still do damage over time. Since I can't get new eyes, I prefer to err on the side of caution.

His camera is not capturing UV directly. When an object flouresces, it is absorbing some of the energy in the UV light, effectively increasing, in most cases, the wavelength of the light that is emitted so that it's within the visible spectrum. At that point, it is no longer UV.

 

[fyrstormer]

Re: Nichia 365nm Light offerings

I would guess that ideally the lenses on such glasses would simply block all UV light and use the near UV light as a trigger for darkening. A car windshield I believe blocks most UV and you would want the light passed through the windshield to be able to activate your sunglasses based on the intensity, I would imagine. Interesting stuff!

You are correct about auto glass. When I get in my car on a sunny day, my glasses lighten up as soon as I close the door. Given the lack of visible tinting on the glass, my guess is the UV protection cuts off just inside of the 400nm range, and my glasses probably respond to UV just outside of that range. That makes sense because, if the lenses block most everything below 400nm anyway, there's no need to darken when exposed to those frequencies since they're already "dark" all the time at those frequencies -- it's only visible light that they need to adjust their tint for, so UV light that's just on the outside edge of the visible range would be the best indicator with enough energy to activate the tint without always selectively absorbing a visible color that I might otherwise want to see.

 

[fyrstormer]

Re: Nichia 365nm Light offerings

Unfortunately, the fact that his hand is clearly lit also means that reflected visible light is skewing the appearance of both the paper and the shadow. Try taking the photo in a completely dark room where the only light source is your mule and let us see that. Unless the shadow was solid black in such a photo with correct exposure, then UV may still be getting through.

I'll take a picture in the dark when I get home tonight.

If there is even a slight chance of a highly reflective surface throwing some 365nm waves back at me, I wear a pair of UV-specific safety glasses. Even rated at blocking 99.9% of UVA/UVB, the 0.1% that gets through can still do damage over time. Since I can't get new eyes, I prefer to err on the side of caution.

I would be fascinated to know how you manage to step outside on a sunny day without hissing and writhing in pain. The ozone layer blocks enough UV that you don't get instant sunburn like you would in space, but there is still far more UV striking the ground outside even on a cloudy day than there is being emitted by my UV Mule.

His camera is not capturing UV directly. When an object flouresces, it is absorbing some of the energy in the UV light, effectively increasing, in most cases, the wavelength of the light that is emitted so that it's within the visible spectrum. At that point, it is no longer UV.

How exactly do you explain the second and third photos, then? If the UV were causing the Mule's lense to fluoresce, the image of the light engine would be washed-out, and if any of the lenses in the camera were fluorescing, the entire picture would be washed-out. The bright spot is clearly centered around the emitter die itself. My camera's UV filter is not blocking all of the UV light, and the CCD is recording it as visible blue light because it doesn't have a facility provided to isolate and record UV wavelengths properly. There are pictures of this same emitter taken using a better camera with a better UV filter, and it is clearly not recording anything but visible light, unlike mine.

 

[Codeman]

Re: Nichia 365nm Light offerings

I'll take a picture in the dark when I get home tonight.

I would be fascinated to know how you manage to step outside on a sunny day without hissing and writhing in pain. The ozone layer blocks enough UV that you don't get instant sunburn like you would in space, but there is still far more UV striking the ground outside even on a cloudy day than there is being emitted by my UV Mule.

How exactly do you explain the second and third photos, then? If the UV were causing the Mule's lense to fluoresce, the image of the light engine would be washed-out, and if any of the lenses in the camera were fluorescing, the entire picture would be washed-out. The bright spot is clearly centered around the emitter die itself. My camera's UV filter is not blocking all of the UV light, and the CCD is recording it as visible blue light because it doesn't have a facility provided to isolate and record UV wavelengths properly. There are pictures of this same emitter taken using a better camera with a better UV filter, and it is clearly not recording anything but visible light, unlike mine.

Okay, it appears to be time for some basic science. The Nicha 365nm puts out far more concentrated UV than what reaches us from the sun. Because of this it has the potential to be far more dangerous. That shouldn't be too hard to understand, assuming that the truth is actually desired. I would hardly call it fascinating, though. It's just common sense.

Basically, when light, in this case UV (which by definition is invisible), hits a flourescent target, there is a transfer of heat to the object and the light that is emiited by the target is at a longer wavelength (lower energy due to the heat loss). In your case, the target (white paper) emits visible (and thus not UV) light that is blue, which is what your camera is capturing. If you camera was actually translating UV as blue, then it would follow that the paper shouldn't appear to be blue to the naked eye since UV light is invisible to the human eye. Yet it does appear to be blue. And that is exactly what your camera is showing - visible blue light that is being emitted by white paper when illuminated by a UV source.

The principle of flourescence is very well understood and clearly defined. I recommend that you google the word if you don't believe me.

 

[McGizmo]

Re: Nichia 365nm Light offerings

I have used a Nichia to excite the phosphor in the H3 vials in the pistons of some of my lights. With my Nikons, I would get an unwanted red reflection off the titanium which could only be the UV light being reflected and registered as red by the camera. Ultimately I purchased a UV filter for one of the Nikon lenses and it for the most part removed this red reflection. I believe that to some extent, UV and IR do get through and register in many of the digital cameras.

I am confused a bit at the discussion regarding the glasses used to interrupt the UV light in the pic above. I think we agree that the white paper is fluorescing as a result of the UV light contacting it. That there is an obvious shadow cast by the glasses on the paper I take as evidence that they are blocking the UV light to a great extent. It would be interesting to see if a Cree UV (395-405 nm) would cause those glasses to darken. My guess would be yes.

I think a number of the UV specific safety glasses you can buy are also tinted yellow and this it to filter out the near UV and blue that is generated by many UV sources. The yellow tint is to enhance the effect of the UV in terms of fluorescence by removing reflected visible light of the source. If the target fluoresces in the blue range though, I would think you are throwing the baby out with the wash. :thinking:

 

[Codeman]

Re: Nichia 365nm Light offerings

The white paper is flourescing due to both the UV light source AND the ambient light in the room. How much of the shadow is non-black due to the ambient light and how much is due to UV light that is passing through the glasses can't be determined in the previous photo. That's why I asked for a photo in a dark room. Even with UV safety glasses, a small amount of UV usually passes through.

Camera sensors are not 100% immune from UV/IR influence, but the manufacturers try to reduce their effect as much as possible. Neither are visible to the naked eye, so the small amounts that do have an effect on the sensor cause color errors when compared to what the eye actually sees. I may be wrong, but I think UV/IR can contribute to chroma errors.

 

[fyrstormer]

Re: Nichia 365nm Light offerings

Okay, it appears to be time for some basic science. The Nicha 365nm puts out far more concentrated UV than what reaches us from the sun. Because of this it has the potential to be far more dangerous. That shouldn't be too hard to understand, assuming that the truth is actually desired. I would hardly call it fascinating, though. It's just common sense.

Basically, when light, in this case UV (which by definition is invisible), hits a flourescent target, there is a transfer of heat to the object and the light that is emiited by the target is at a longer wavelength (lower energy due to the heat loss). In your case, the target (white paper) emits visible (and thus not UV) light that is blue, which is what your camera is capturing. If you camera was actually translating UV as blue, then it would follow that the paper shouldn't appear to be blue to the naked eye since UV light is invisible to the human eye. Yet it does appear to be blue. And that is exactly what your camera is showing - visible blue light that is being emitted by white paper when illuminated by a UV source.

The principle of flourescence is very well understood and clearly defined. I recommend that you google the word if you don't believe me.

Oy vey. The SECOND picture. Look at the SECOND picture. The one where the emitter is pointed DIRECTLY at the camera. Do you see the burnout in the center of the image, where the emitter is located? THAT is what I'm talking about when I say the camera is responding directly to the UV light. The emitter looks nothing like that to my eyes.

I know the blue fluorescence in the FIRST picture is the paper fluorescing from exposure to the UV light. That is not what I've been talking about for the past several posts. However, since you bring it up, the paper is not fluorescing from exposure to visible light -- that is simple reflection, nothing more. Fluorescence is the emission of radiation at a different wavelength than the radiation striking the target object. I suppose you could say the paper is exhibiting a tiny amount of IR fluorescence due to the visible light striking it, and I would be wrong to disagree, but IR fluorescence is completely irrelevant to this topic so I'll leave it at that.

- - -

Regarding my camera's response to DIRECTLY INCIDENT ultraviolet light: UV is ionizing radiation. Ionizing radiation is damaging because it knocks electrons off the atoms it strikes, sometimes causing those atoms to form ionic bonds they otherwise wouldn't form and sometimes neutralizing their existing ionic charges causing them to break their existing bonds. UV moves electrons around when it hits things.

The light sensor in my camera is called a charge-coupled device; its front and back surfaces are electrically charged, and photons that pass through the red, green, and blue pixel filters are registered as a result of the excess electrons they push through the CCD upon impact.

So, given that UV moves electrons around when it hits things, and given that the CCD has a ready supply of electrons on its surface just waiting to be moved around, and given that any UV making it through the UV filter will most easily pass through the blue pixel filters, it should come as no surprise that my camera would read UV as really bright blue light.

- - -

As for the Nichia 365nm LED emitting far more concentrated UV than the Sun does: I agree that the lack of visible light causes unique problems as far as your pupils opening wide and letting lots of UV strike your retinas, there's no denying that. However, visible sunlight striking the ground on a sunny day is ~1000W/sqm, so even if the UV striking the ground were a fraction of that, it would still far exceed the UV output of my UV Mule. Again, not a good idea to stare at it, but hardly more potent than the Sun.

 

[McGizmo]

Re: Nichia 365nm Light offerings

Ray,
I recall shooting IR film a long time ago and I had to manually focus the lens based on a red hatch mark on the lens which was slightly off set from the white hatch mark used for visible light. I think any invisible light passed through the lens and sensed by the camera sensor is not going to be in focus when the visible light is.

I agree that a shot in a dark room would be nice but seeing that the shadow of the glasses frame is similar to that of the lenses themselves leads me to believe that the UV blocking is significant.

I found THIS page on cameras which has some bearing on the discussion.

 

[fyrstormer]

Re: Nichia 365nm Light offerings

Picture of my glasses acting as a UV filter, this time in complete darkness, as promised:

The fluorescence of the paper was extremely bright, as you can see, bright enough to cause a little burnout in the center of the image. I'm not entirely sure what's causing the penumbra around the shadow of the lense, but I think it has something to do with fluorescence from the paper striking the lense and reflecting off it.

 

[Bass]

Re: Nichia 365nm Light offerings

frystormer - thanks for your time in doing these shots. I hope your were wearing eye protection :nana:

It appears clear to me that your glasses are blocking the majority of the UV from your light. Interesting penumbra (have to admit a vist to wikipedia to find out the full meaning ). I presume this is due to reflected light from the paper?

Thanks again for all your pics and discussions with others regarding this light; interesting stuff. I will be ordering one in a few weeks.

 

[fyrstormer]

Re: Nichia 365nm Light offerings

It's not strictly relevant, but I dug out the cheap $2 UV light/magic marker I bought from DealExtreme and used it on my glasses, and sure enough its 400nm LED darkened the lenses in seconds. So that little mystery is solved.

Considering this was done by a little 5mm LED running on three watch batteries (4.5V), it's a testament to the much-brighter 365nm Nichia emitter that it puts out too little 400nm light to darken my glasses even at point-blank range. It obviously has a very tight emission spectrum. :thumbsup:

(no lenses were injured in the making of this photo )

 

[Bronx68]

Re: Nichia 365nm Light offerings

I'm looking for a source for Nichia 365nm leds.

 

[derangboy]

Re: Nichia 365nm Light offerings

http://www.springerlink.com/content/668j066286443722/fulltext.pdf

The link details a study on the feasibility of using 365nm LED light for use in sterilization of water. My current water source is borderline for fecal coliforms but passes all other criteria for municipal drinking water. I hope to have a few tests done this summer to see if I can sterilize small batches of well water to potable standards. Maybe McGizmo magic can deal with pesticide residue as well? :thinking:

 

[GLOCK18]

Re: Nichia 365nm Light offerings

Are these still available?

 

[McGizmo]

Re: Nichia 365nm Light offerings

Are these still available?

yes

 

[Sable]

Re: Nichia 365nm Light offerings

Well, posting for the first time in a while to ask a (maybe?) silly question...

I recently moved out of Alaska to southwestern Arizona, where I understand some of my new neighbors are scorpions. I know a lot of scorpions fluoresce under UV light, but is this the right wavelength to make them glow at night? I haven't gotten stung yet wandering around the desert after the sun goes down (night photography in a place where there's not 340 days of cloud cover is a whole new world!), and I'd like to keep that the case as long as possible.

 

[tino_ale]

Re: Nichia 365nm Light offerings

Does anyone know if the UV mule could be usefull to sterilize or at least partially decontaminate stuff ?

I was thinking water decontamination, or killing germs on your cellphone, keyboard, mouse, keys etc.

If yes, any idea what kind of time would be required with the Mule so actually do something ?