23 Feb
2010
23 Feb
'10
7:34 p.m.
If you look at one in the microscope=2C it looks like
an LED with some sort=
of phosphor painted over the semiconductor. Is that how these things work=
=2C its really a high efficency IR LED=2C with a phosphor doubler to bring =
the wavelength into visible? Just speculating...
Most, if nto all white LEDs are actually a blue LED device coupled with a
yellow phosphor. If you shine UV light sourve on one, it will glow yellow
due to the phosphor. UV LEDs work well for this (yes, said pound shop had
some UV LED torches (flashlights) at 2 for a pound, designed to be used
to show up the fluorescent markings on banknotes to detect forgeries. I
added one to my toolkit, it's very useful for detecting flourescent
markings on all sorts of otehr things, for checking the colour of
phosphor in display panels, and the like).
I was using them in a ring light for a downhole well camera. Not that expe=
nsive=2C about $6 each.
Has anyone ever tried them for flim photograhpy? THe data sheets I looked
at showed a fairly continuous output spectrrum (unlike the pure colour
LEDs, of course), which could presumably be filtered into something that
looked like daylight to colour film.
-tony