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Optical Bench REDUX: Digital Switching can have Analog Functions!

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--- Quote from: RJHayward on April 02, 2023, 04:25:44 pm ---   If you take a look at photo, that's a decorative optical fiber 'tree', although I'm not sure if in this case the type of fiber useful in longer distance digital links.   The communication type will have a fiber core that has different refraction index.

--- End quote ---

Yes, it would be interesting to know (no sarcasm is either intended or implied here, I'm just illustrating a point), the difference between a circa (I don't know the price, so only guessing), $1 budget set of decorative tree, optical fibres, and a full on research team/company, with a $50 million dollar, annual research budget, and using the latest, high tech (possibly early prototypes, not available for sale, anywhere), optical fibres, of just about the highest available quality, anywhere in the known universe (except dreams and star trek, or similar).

   I've shown this method before (please see photo).  By snipping off the garden light's LED those two leads, from that little circuit board, can be conveniently plugged straight into a proto board.  Here, I've just simply added in a RED LED from parts bin, but various other items, such as a transistor can utilize the garden light output (from the simple buck circuit).
   That voltage multiplying buck circuit runs at some 220 khz, producing around +3volts for the LED.

   Now, for my purposes that garden light isn't any where near to being switched due to light from a few strands of the fibers (or even the whole bunch), as the intensity is just too low.  But still, I'm curious as to what voltage (changes) happen...A couple of fibers worth of light might only cause an(edit) increase of a couple of micro-Volts.  (edit) That, of course, is measured at the solar cell, nominal 2.5 volts in bright light.
Certainly, that switch arrangement requires a quantity of light you would expect from a full flashlight, rather than a couple strands of fiber, where the flashlight illuminates the whole bunch.
Just curious.

   Thanks, MK14.
   Previous ventures soaked up about $ 25 k, to obtain a 'real' office setting and start buying needed tools.  But those are single instance expenses, office rent ongoing but not very much ($220).
Ongoing, beyond initial seed money, was rent and labor time...lots and lots of labor time.  I took on a job, when it was offered, so that helped with paying the office rent.  Overall, was 5+ years with some productive outcome...(mostly gained wisdom), and better appreciation for US Patent Office procedures...

   Now, since I'm going to be trying out a single, extremely feeble portion of total light, via one isolated strand of that (decorative tree), I started on kitchen table, getting a rough count, (of total fibers there).

   The bundle diameter is close to 9/16 inch, where the area calculates to, est. π/12.6 sq inches (roughly 1/4).
The fiber 'gauge', lacking a handy micrometer, was then estimated: 20 fibers side by side takes up 11/32 ". comes to est. 17.6 thousandths of inch.  So, I used 20 here, Fibers est. at 20 thousandths diameter.

   Run that out, total area divided by area of a single fiber (fiber is est. π\ 10,000); that divides to 10,000/12 or about 833 fibers !

   (Wow, lucky, that's a 'magic' number...or at least 0.833 is...    That's 6/7ths).

   Anyway, if you figure around 1000 fibers, or 833, that's the factor of reduction.  So, if a 10 milliwatt LED manages to shine about 4 mW directed into that bundle, you 'could' expect around 4 MICROwatts at the end of exactly one fiber, separated and isolated by dark cloth. 
   That also would apply, approximately, to say a viewer's perception, each of the tiny tiny points seem almost to be less intense,...than the stars, individually seen, at night.  Wow.

These preliminary estimates are to be checked and measured next, on the bench.

   Measuring voltage response, using solar cell as sensor, like the garden light's do;
   With minor light leaks, through cloth, the little solar cell reads 0.030 (30 milliVolts), and then with 'signal' we read 0.520 volts, approx. which is the response I'm looking to measure, while using small bundle.
Small fiber bundle is approx. 1/16 of area of full, 1000 strands, or about 62 fibers, at 250 microWatts total.
If that's correct, it's close to 4 microWatts estimated, per fiber.  (That's when assuming 4 milliwatts goes into the whole, 1000 fiber bundle.)


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