Recently on the neon mailing list the topic of eye fluorescence came up. That is, the glow one can see in the eye that’s being illuminated with UVA, AKA Black Light. There was some question as to whether the effect even happened or not. Having had a typical Boomer teenager’s bedroom, that is, one flooded with black light and decorated with black light posters, I knew that the effect was real.
The first thing I did was go to the bathroom (a dark place with a mirror) and shined the UV LED from this little gadget across one cornea while observing in the mirror. Sure enough, there was the glow. Eerie looking.
I figured that a photo might be nice so I grabbed my trusty old Nikon Coolpix 995 and tried to shoot the effect. Between the camera’s UV response, its slow sensor and my shaking, no workee. I added a UV filter but apparently UVA is below the filter’s cutoff. I gave up.
I posted about my failed experiment to the list but then I decided to try a different approach. Different camera and different light source. I laid down that $1000 camera and picked up my $169 special, a Canon PowerShot A590. This low cost camera has several things that I love. Fast sensor, fast focus, image stabilization and last but not least, it uses ordinary AA NiMH batteries. Yaaaay for the last part. I’m sick of proprietary lithium batteries.
This is the light source.
This is one hot little black light. The trouble light made a nice fixture that shielded the camera from the direct rays. Back to the bathroom. After playing around a little, SUCCESS!
In the below picture, the black light is off to the right, slightly behind the plane of my face and out of the frame. It is projecting its light across my eyes and is also reflected off the front surface of the mirror. If you look you can see my other eye also glowing, though not nearly as brightly. That’s from reflected light, since my nose blocks the direct beam.
Is that a Tron eye or what? :-) This camera also is UV responsive but not nearly so much. More importantly, that image stabilization that I mentioned earlier really showed its mettle. That is a one second exposure, done handheld with no tripod. Impossible with a conventional camera.
Unfortunately the UV totally nuked the auto-focus. I did the best I could and this is the best picture of several but it’s still fuzzy. Still good enough to see that zombie glow :-) Notice a couple of other interesting effects.
First, the flash cover is fluorescing blue. I had to color-correct this photo to remove a strong blue overcast and the process dimmed the lens. In the original it is glowing brightly.
Next is the rather rough look of my skin. Black lighting is the trick that cosmetic outfits and dermatologists use to show sun skin damage. I’ve had a lot of sun exposure and a couple of severe burns. My skin shows the damage.
While I was in the dark bathroom, I took some photos of some other interesting effects. This UV CF lamp really cooks and the intense UVA makes things glow brightly.
This is a photo in regular light. Note that it is hand-held without a flash and used a 1/40 second exposure. Love that image stabilization!
The hair dryer is in the center. To the right is the charger for my electric toothbrush. To the right is a Walmart receipt. to the left of the hair dryer nozzle is an electroluminescent night light. To the right of the nozzle is a wall wart that powers a set of speakers. Gotta have tunes in the shower :-) Now look at the black light version.
Zowzer! Look at that hair dryer and night light glow. Also the Wallyworld receipt. Interestingly enough, the side with the printing doesn’t glow very much. Apparently the thermal compound that makes the paper heat-responsive blocks UV. The toothbrush charger glows some but the cord glows brightly. I’ve noticed that a lot in white power cords. I’m not sure why they put fluorescent dye in the plastic but a lot of manufacturers do. Finally, note the ink on that wall wart. It too is glowing. The other warts aren’t. Don’tcha just love the world of UV?
This is a shot of the black light shining on a conventional CF light. Notice the eerie glow of the tube. In the flesh, it looks almost liquid and very deep. The red components of the phosphor respond much better to UVA than do the other components. Typical. The glass is also slightly fluorescent. Also note how the cement that attaches the glass to the base glows. Sorry for the blurry pic. In real life, the cement glows bright green, almost like the night light.
Finally, this shot. Look at that hair brush scream. It is NOT a day-glo colored brush in normal light. It’s blinding under UV. You can clearly see the cement and the tubes on the CF light. Also note the white rectangle on the left. That is a mailing label. Most non-glossy paper is coated with a blue fluorescing dye to make it appear whiter under normal light. Both sunlight and fluorescent lights emit enough UV to make the paper “sparkle”. It looks bright blue under a UV light.
They put the same dye in laundry detergent and for the same purpose. It makes clothes look whiter. That’s why white cloth and thread glows brightly when exposed to black light, such as in a club.
Well, this has been a fun evening of playing Mr Wizard!
JohnPosted by neonjohn on July 14th, 2008 under Cool Stuff, Science