1.
Open light meter case carefully.
2.
Check battery by holding on/off switch on “test” and observing meter
reading (indicator should be to the far left of the meter scale, past the
“bat.” arrow).
3.
Zero meter if necessary by adjusting “zero” dial.
4.
Check calibration switch. Flick switch to “dry” for measurements in
air; to “wet” for measurements in liquid (e.g. in culture flask filled with
distilled water).
5.
Adjust
“full scale irradiance” dial (quanta sec-1 cm-2) to a
higher reading than anticipated.
6.
Carefully handle light probe, especially the spherical sensor on the end.
Place sensor in area when light intensity is to be measured.
7.
Switch on/off switch to “on”. Adjust “full scale irradiance” dial
to suitable level for accurate reading.
8.
Read the appropriate scale for light intensity measurement.
Note that there are two scales on the meter: the top
scale from 0-1
and the bottom scale from 0-3. This corresponds to
the calibration
factor chosen on the irradiance dial. For example:
·
If the irradiance dial is set at 3x1016, then use the bottom
scale, such that a meter reading of 2.5 would be recorded as 2.5 x
1016
·
If the irradiance dial is set at 1x1015, then use the top
scale such that a meter reading of 0.75 would be recorded as 0.75 x1015
…or 7.5 x1014.
·
A meter reading of 8.0 on 1x1015 scale and 0.8 on 3x1016 scale
are the same measure, ie. 8 x1015
9.
After measuring light intensity, switch on/off switch to “off’ and
carefully replace light probe in light meter case.
Dry light probe gently with a tissue if wet. Close light meter case.
To convert quanta cm-2 sec-1
to micromol photons m-2 sec-1, use the formula:
y (micromol photons m-2 sec-1)
= quanta cm-2sec-1
6 x 1013
The unit micromol photons m-2 sec-1
is equivalent to the older term microeinsteins m-2 sec-1