The
following glossary offers a brief
summary of terms and
definitions used in the application of UV lights and products.
Download The "Light Measurement
Handbook" Click. 
- Ultraviolet
Light Spectrum
- Light with wavelength
ranging from 100-400nm.
Catergorised as UVA, UVB and UVC.
- Click to view spectrum
- Photochemistry
- Chemical reaction driven
by the absorption of visible
or ultraviolet light
- Coherent
Light
- All photons are in
phase. Eg Laser
- Incoherent
Light
- Photons are at randon
phases. Eg incandescent light
bulb
- Radiant
Energy
- Total amount of energy
emitted from a source over a
given period of time
- Joule
- 1 Joule= 1 watt x
second.
- Inverse
Square Law
- Irradiance varies in
inverse proportion to the square
of the distance. E=I/d2
- Irradiance
W/m2
- Total radiant power
incident from all upward
directions on a surface. Units W/m2
- Fluence
Rate W/m2
- Total radiant power
incident from all directions onto
a small sphere.
- Fluence
(UV Dose) J/m2
- Total radiant energy of
all wavelengths passing all
directions through a small sphere. J/m2. Approptriate term for UV
disinfection because a microbe can receive UV power from any
direction.
- Quantum
Yield
- Measurement of the
photon efficiency of a
photchemical reaction.
- Radiometer
- A device that senses the
the total irradiance
incident on a sensor element. The photon flow is converted into an
electrical
current.
- Actinometry
- An actinometer is a
photocehmical reaction for which
the quantum yield is known. The measurement of the chemical yield after
exposure allows the determination of photon flow.
- Refractive
Index (n)
- The ratio of the speed
of light into a vacuum to that
of a specific medium.
- UV
Disinfection
- Photochemical
reaction of a microbe absorbing light
of the wavelength range 200-300nm. The UV light is absorbed altering
the RNA/DNA thereby disrupting the cell membrane.The cell either dies
or the microbe is unable to replicate
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