There are very few ?cutting edge? applications for infrared LEDs. They
have been around for yonks. Standard CDs use LED IR lasers. DVD use
red LED lasers, but computer DVD drives have both IR and red to
accommodate both formats.
Shorter wavelength LEDs are a different matter. Advances in chip
configuration allows more light to escape, mainly from reverse
mounting, so efficiency is now high enough to compete financially with
incandescent bulbs in many apps. Automotive, domestic lighting,
diagnostic equipment. Unit cost is still high but economies arise due
to reliability and lower power requirements.
White LEDs are now being slotted into all manner of goods, mainly
torches at the moment. They aren?t actually white though, deriving the
colour from a phosphor film on the surface of recently developed blue
LEDs. It has to be said though that the efficiency of the drive
circuitry in very often poor, even where specifically designed chips
are employed. Hopefully better electronics and magnetics will evolve
though no major advance has been achieved with ferrites since the
1930s!
Ultraviolet is where the real stuff is going on. For quantum reasons,
better white rendition can be generated from phosphors activated by
UV. There is also much more background in this because fluorescent
lights also convert UV to visible. If you are old enough, you will
remember early striplights inducing horrid green pallor and visibly
flickering. Now, they are very good.
UV LEDs are finding application where previously the only realistic UV
source was a quartz tubed striplight (without phosphor coating of
course), such as note validation, materials instrumentation and
perhaps EPROM erasers if the frequency can be raised a bit.
UV lasers, which are similar to LEDs, are being developed for high
density CD because the shorter the wavelength, the more compact the
data.
Hope this is a suitable wee taster.
Best |
