Features:
Replaces 4 separate instruments
Thermal Radiation (IR)
Ultra Violet (UV) level
Visible Light (Lux or Foot-candles)
Temperature (°C or °F)
Sized like a small mobile phone
Easy one handed operation
Large, easy to read display
Maximum & minimum with time
Optional data logging
A
single instrument enables measurement of the three types of
radiation that are of most interest: visible (Lux), thermal
radiation and ultraviolet. The 774 also measures temperature
in °C or °F.
Thermal
Radiation (IR)
The measurement of thermal radiation (shown as W/M2
or btu/hour/ft2) allows the user to estimate how
much solar heat is coming through windows, check the
performance of heat reflecting films, measure the heating
effect of lamps on objects etc
Visible
Light
The amount of visible light is important, not only to check
illumination in work areas, galleries etc but also to control
damage to light sensitive objects that is also caused by
normal light. Measurements can be displayed as Lux or
Foot-candles.
Ultraviolet
(UV)
For many years it has been recognized that one of the major
causes of damage to museum objects and other sensitive
objects, soft furnishings etc is the fading and rotting effect
of light on the object. The most damaging part of the
illumination is its ultraviolet content. Since 1976 Littlemore
Scientific (ELSEC) has been providing instruments that enable
the conservator to measure the UV content of light and thereby
protect valuable exhibits. Using the 774, measurements can be
taken of the proportion of UV present (mW/lumen), the total
amount of UV (mW/M2)
Data
Logging
The optional data-logging function enables over 10,000
readings of all four parameters to be automatically taken at
selectable intervals (every 10 seconds to 1 hour). The saved
data can then be transferred to a computer by a wireless
infra-red link (IrDA compatible). Many modern computers have
an infra-red interface built in; for those that do not,
adapters are available. When logging data the 774 can be
turned off to save power and the built in clock will turn the
unit on whenever a reading needs to be taken, this enables a
774 to be left taking readings for months at a time. Software
is provided to display the measurements and save the logged
data in CSV format that can be accessed and displayed by many
programs (e.g. Microsoft Excel).
Easy
to use
Much trouble has been taken to make the 774 as easy to use as
possible. Anyone can take measurements straight out of the box
with little, if any, reference to the instruction manual. The
appropriate button is pushed depending on the measurement
required and the reading is taken. The unit automatically
turns off 10 seconds after the last reading unless a button is
held down for over 5 seconds, this causes continuous
measurements to be taken until another button is pressed. The
large 8 line display enables an easy to use menu system to
select the more advanced functions, change units etc.
Units
of measurement for UV
Traditionally UV has been measured in museums as the
proportion of ultraviolet present. This result is useful for
checking a particular lamp or window because the proportion of
UV does not change with the distance from the light source.
Using a simple rule, the amount of UV on an object can be
limited (it is usual to arrange that the proportion of UV
should not exceed 75mW/lumen in museums). The damage is done
by the total amount of UV falling on the object, so it is
useful to be able to measure this directly, especially if non
standard amounts of illumination are required. The amount of
UV should be as little as possible but in general should not
exceed 20mW/M2.
