A little more on Fluorescent Lamps

[P3D <JValaVIDI@xxxxxxx>]

There is no mention of a specific Color Rendering Index (CRI) for these lamps

other than to say it is "High", but they do mention that the lamps with a
"-20" 
suffix like a BF4142-20B, would have a color temperature around 5600 to
6000K. 
 This should be plenty cool enough for proper rendition.  These "-20" colored

lamps are made specifically for LCD back lighting applications, so it is also

important for them to be properly color corrected.  The part Nos. I gave had 
"-01" suffixes which are a "Warm White" color.  Here are some other lamps you

would probably rather have:

Description              Part Number                Price
6.5mm Dia. X 50mm        BF650-20B                  $US10.00
6.5mm Dia. X 100mm       BF6100-20B                 $US10.00
6.5mm Dia. X 178mm       BF6178-20B                 $US10.00
6.5mm Dia. X 200mm       BF6200-20B                 $US10.00
6.5mm Dia. X 225mm       BF6225-20B                 $US10.00
6.5mm Dia. X 262mm       BF6262-20A                 $US10.00
29.0mm Wide X 134mm      BF6U22134                  $US20.00  U-Shape Lamp
          (This U-Shaped Lamp may be something interesting to look into!)


   As far as Color Temperature and Color Rendition goes, were never going to

hit a CRI of 1.0 (I dont think!).  But when it comes down to the fine
details
 of the color characteristics of the lamps, the only way to get what you want

is to have the lamp vendor mix a custom blend of phosphors for your specific
needs.
However, be warned... you have to know what you want before you call these
folks.
They will want spectral curves of the light characteristic you want.  Often
times, 
they already have a custom blend they made for someone else that they can mix
up 
again for you and put into your lamps.  They can send you the curve for that
blend
and its up to you to decide if its the color you want.  But dont ask for
just 
one lamp, they will probably want to make a minimum run of a few hundred or
so and 
charge you for their efforts.  But it can be done!  The "-20" color mentioned
above
is made from a nice blend of Red, Green and Blue with rather broad spectral
bands
for each of the colors.  Its probably about as close as your going to get
without 
lot of trouble.

   And as far as "flicker" goes; Eric, you really didnt mean that when you
said 
"the diffusion material tends to mitigate the flicker", did you?  Flicker is
flicker,
its a temporal/intensity thing.  I always thought it would be great to have
the optical equivalent of a Low Pass Filter like they have in the electrical
domain!  All electronic ballasts that run off of DC operate at frequencies
between 20 - 40kHZ.  This is both 
optimum for the lamp and the magnetics in the ballast.  The persistence of
the phosphor
is much longer than this also so, realistically there is no flicker in a
fluorescent lamp powered by an electronic ballast operated from a DC
source!.... as far as I can figure it.



Hoping this does not draw fire from those who think this "non-3D" thread is
going on too long,

John Vala
Virtual Imaging Devices, Inc.


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