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Really bright yellow LEDs?

Discussion in 'Electronic Design' started by Phil Hobbs, Dec 14, 2013.

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  1. Martin Brown

    Martin Brown Guest

    There were some very dim blue LEDs available 30 years ago. Mostly used
    on high end audiophool amplifiers and the like as indicators and just
    barely visible when lit. ISTR they were Russian silicon carbide based.
    Not mentioned on Wiki (except as available from 1990's).

    Pretty sure they were on some high end kit in the late 70's early 80's.
     
  2. Ecnerwal

    Ecnerwal Guest

    I did notice that a couple of places (Ididex, Coherent, among others)
    make a 577nm diode-pumped laser, but seem to keep it under tight wraps
    and presumed high expense as a "medical" laser, so it seems unlikely to
    be suitable.
     
  3. Phil Hobbs

    Phil Hobbs Guest

    Yeah, I'm fighting a worst-case path loss of 80 dB optical, so I really
    need a lot of photons. Turns out I can get quite a few just by
    filtering a 4000K white LED, because 578 nm is pretty near the peak.

    You know your LEDs are pathetic when a blue one, driving a phosphor,
    filtered down to 5 nm wide, is still 100x brighter than yours and has
    10x better wall plug efficiency.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC
    Optics, Electro-optics, Photonics, Analog Electronics

    160 North State Road #203
    Briarcliff Manor NY 10510

    hobbs at electrooptical dot net
    http://electrooptical.net
     
  4. Guest


    Have you considered using a low pressure sodium vapour lamp for the yellow light?

    Lots of problems in that approach,but you do get a lot of light per watt. From Wiki

    "Another unique property of LPS lamps is that, unlike other lamp types, they do not decline in lumen output with age. As an example, mercury vapor HIDlamps become very dull towards the end of their lives, to the point of being ineffective, while continuing to consume full rated electrical use. LPS lamps, however, do increase energy usage slightly (about 10%) towards theirend of life, which is generally around 18,000 hours for modern lamps."

    Dan
     
  5. Phil Hobbs

    Phil Hobbs Guest

    Thanks. The sodium lines are at 589 nm, which won't work in my
    application. I really need 578 and 598 nm. If I could do it at 590,
    there are a ton of bright LEDs there as well.

    Cheers

    Phil Hobbs



    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC
    Optics, Electro-optics, Photonics, Analog Electronics

    160 North State Road #203
    Briarcliff Manor NY 10510

    hobbs at electrooptical dot net
    http://electrooptical.net
     
  6. josephkk

    josephkk Guest

    Cree had blue LEDs (SiC) over 30 years ago, but they had lousy spectral
    purity and were expensive (>3$ ea. at 1 mW).

    ?-)
     
  7. Tim Williams

    Tim Williams Guest

    So you need just 10nm either side of it?

    How about... erm, hetrodyning what, a CO2 laser with it?

    Better yet, a comb generator, and bandpass whatever you like... make an
    optical Wadley Loop and cover the whole range!

    Okay, maybe a *little* crazier than an LED array, certain notches (such as
    the present problem) aside.

    Tim
     
  8. Phil Hobbs

    Phil Hobbs Guest

    The current best guess is either a good white LED or the very greenest
    among the high-efficiency yellow ones, shining through a 3-5 nm wide
    interference filter.

    Cheers

    Phil Hobbs

    --
    Dr Philip C D Hobbs
    Principal Consultant
    ElectroOptical Innovations LLC
    Optics, Electro-optics, Photonics, Analog Electronics

    160 North State Road #203
    Briarcliff Manor NY 10510

    hobbs at electrooptical dot net
    http://electrooptical.net
     
  9. josephkk

    josephkk Guest

    Unfortunately both wavelength distances are beyond convenient thermal
    pulling distance if i understand correctly. Plus, it could be hard to
    regulate target wavelength well. Maybe a diffraction grating trick would
    help.

    Keep on thimkimg. >?-)
     
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  12. Phil Hobbs

    Phil Hobbs Guest

     
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