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Fluorescent Reflector

Make use of the shorter wavelengths for more visability
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So, someone stole my bike light. Now I only have a reflector. Out of interest, I took the rear reflector off my bike and subjected it to my hideously over-specified optical test equipment.

It's not very good. Here's why: It's a shiny metalic cube- corner reflector, covered in red-transparent plastic. Now the cube-corner reflector I have no issues with. It's a good way of getting light out in lots of directions from a light source that may be coming in from all sorts of angles. The red-transparent plastic is where the issues lie.

The red plastic basically acts as a low pass filter. White light in, red light out. The whole spectrum shorter than about 600 nm is wasted. It just warms the plastic up a bit*.

We can do better. With fluorescence. Simply embed red- emitting quantum dot CdSe nanoparticles in the plastic. Much better visibility as not only the (red portion) reflected light will be seen, but the quantum dots will harvest some of the blue/green/orange light and emit that back at the driver.

* or a lot of you put 600W Xenon arc light down a liquid light guide at it.

bs0u0155, Aug 19 2014

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       //Now the cube-corner reflector I have no issues with. It's a good way of getting light out in lots of directions from a light source that may be coming in from all sorts of angles.//   

       As I understand it, a cube-corner reflector returns light in the direction it came from - is that not the case?   

       But I like the fluorescence part. Qdots are awesome, but I'm not sure if they're cheap enough for this application.
MaxwellBuchanan, Aug 19 2014
  

       The nice thing about corner cube reflectors is that, regardless of the incoming direction, the light goes back out on the exact reciprocal.   

       Your fluorescent dots will emit weakly (low QE of fluorescence) and diffusely from the surface exposed to the light.   

       I'm not saying the idea can't work, just that the gain will be minimal, and if the dots intercept some of the red light, might even be negative.
MechE, Aug 19 2014
  

       //a cube-corner reflector returns light in the direction it came from//   

       You're correct, my description was messy.   

       //cheap enough for this application//   

       They're going to be using them for increasing the efficiency of solar panels, I suspect they'll be cheap soon. Also, minor gains for massive money is a hallmark of any bike part.
bs0u0155, Aug 19 2014
  

       //Your fluorescent dots will emit weakly (low QE of fluorescence) and diffusely from the surface exposed to the light.//   

       QD's are >80% quantum yield, actually, that's just the ones I use and they've got biology goop all over them, plus, it's free (red) light. QDs emit equally in all directions. This is a very good thing. It means that some light will go back to the source, some light will hit the reflector, and go back to the source, some will go out of the sides. Now, at the sides a simple mirror can re-direct that backward.
bs0u0155, Aug 19 2014
  

       //Also, minor gains for massive money is a hallmark of any bike part.//   

       While this is true, the ones for whom it is especially true tend to have as little in the way of reflectors as they can legally get away with.
MechE, Aug 19 2014
  

       // little in the way of reflectors as they can legally get away with//   

       with the increased efficiency of the bs0 Quantum Reflector*, they can shave off that precious gram!!!   

       *$299 regular $345 for the Aero model
bs0u0155, Aug 19 2014
  

       <off topic> [bs0] - what are you using Qdots for? <\ot>   

       Actually, thinking about it, I haven't noticed Qdots being conspicuously bright (in their respective emission colour) in ambient light - but that's indoors (fluorescent lights - probably not a lot of blue and very little UV).
MaxwellBuchanan, Aug 19 2014
  

       Off topic. We're using them for imaging low-copy number ion channels in the mitochondria. The calcium uniplex / mito BK Ca2+ channels. Electro physiology tells us that there are <10 of these per mito sometimes, so if you want to see them you need something that doesn't bleach. Even better if it's 2-photonable. Better still if you can see them in EM
bs0u0155, Aug 19 2014
  

       <wildly off topic> how do you selectively bind them to the chosen proteins? Are they antibody-coupled, or have you got something like a streptavidin or his tag [edit: forget I said his tag; that would be stupid] on the channel protein? <\wot, and apologies to innocent bystanders>
MaxwellBuchanan, Aug 19 2014
  

       Absolutely bog-standard secondary antibodies. We have well checked primaries. Not so useful for localization, a 2 antibody chain can put you anywhere in a 30nm sphere.   

       If you can tag your protein miniSOG is great. I can't, tagging the proteins screws their function, native expression levels (<10 proteins) would render them practically invisible, overexpressing them is asking for trouble.
bs0u0155, Aug 19 2014
  

       Hmm. Hadn't heard of miniSOG, just Googled it, way cool. Thanks!
MaxwellBuchanan, Aug 19 2014
  

       //apologies to innocent bystanders//
Any science talk is good; doesn't matter when or where it shows up.
Also, where do you get (and why do you have...) a 600W Xenon arc light and a liquid light guide?
<back on topic> Can't say I know much about fluorescent quantum dots, but the idea certainly has merits. Maybe use wave guides or diffraction gratings to direct the light you don't want reflected (ie. not red) to the fluoro dots, where it gets converted to red; while the (incident) light you do want goes (more-or-less) unimpeded to the reflector.
neutrinos_shadow, Aug 20 2014
  

       Can you stick the quantum dots in a confocal etalon cavity (one etalon for each corner reflector) to increase the conversion efficiency and directionality of the red light?
xaviergisz, Aug 20 2014
  

       Fireflys strapped to the handle-bars.   

       Alternatively, if all you want to know is "what's in front of the bike?" then something like sonar, or catfish with long feelers might work.
not_morrison_rm, Aug 21 2014
  

       ^ an iPad app.
FlyingToaster, Aug 21 2014
  

       //where do you get (and why do you have...) a 600W Xenon arc light and a liquid light guide?//   

       You take a 300 W Sutter DG4, a need for more light, the internet, some cowboy engineering* a bigger fan and Boom!** you have a 600W 10,000 lumen light source with a good amount of UV.   

       *eventually some proper engineering   

       ** the first time at least, the second time we put a better power supply in.
bs0u0155, Aug 21 2014
  


 

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