"Full spectrum", although lacking any specific definition accepted
throughout the lighting industry, sounds to me like something not what one
wants anyway to best-satisfy lighting needs live organisms that have
lighting needs. This is despite replication of sunlight in spectral
properties satisfying most "proposed definitions" of "full spectrum".
Replication of sunlight in spectral properties is not the optimum for
artificial lighting to satisfy lighting needs of organisms that have
photochemical processes that make such organisms require light. The
reason is that such organisms do not make good use of all wavelengths that
are present in sunlight.
Green light is wasted on plants since plants do not much absorb and
therefore do not make much utilization of green wavelengths. This is why
fluorescent lamps made for growing plants specialize in producing
wavelengths that chlorophyll utilizes - mainly red and secondarily blue.
Live coral has a requirement of light best-satisfied by wavelengths in
the blue-violet to mid-blue range (near 410 to mid-400's nanometers).
Some members of the animal kingdom have a requirement of Vitamin D, and
a way of satisfying such is with ultraviolet of wavelengths somewhere in
the low 300's of nm. Humans are an example of members of the animal
kingdom that can have Vitamin D requirements satisfied by such UV or also
by ingestion of Vitamin D.
Beyond that, spectral sensitivities are mostly in known and suspected
photoreceptors in eyes of members of the animal kingdom - ranging from low
400's to close to 590 nm, in addition to one UV-centered one specific to
arthropods and centered around 350 nm (give-or-take and maybe). The
longest wavelengths needed for good color vision are wavelenths utilized
mainly by the longest wavelength vision photoreceptor. The longest
wavelength one known used in vision by anything with eyes (as far as I
know) is not centered/peaking at wavelengths much longer than those of the
longwave/"red" photoreception mechanism of humans. And triphosphor
fluorescent lamps with most "red" output in a single very narrow band
centered at 611 nm achieve a color rendering index of 82-86! I saw a
published spectrum of a fluorescent lamp with rated color rendering index
of 98, and most of its red/reddish output was at wavelengths well below
650 nm!
Bottom line - I advise against buying into some notion that you need
"full spectrum" or "spectral replication of sunlight" to satisfy
photochemical requirements of organisms, since organisms with light
requirements do not require nor can even utilize most of the wavelengths
in sunlight. As an extreme example of what is in sunlight ay Earth's
surface and useless for probably anything - the infrared wavelengths that
are able to penetrate the atmosphere but not water, generally most from
about or hardly over 1500 to low 2,000's nm.
- Don Klipstein (
[email protected])