DOCID#: CD-M-BIM-7001D
U S E R M A N U A L
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5.6.2 Relative measurment
（
dB
）
The dB measurement mode displays the absolute value of 10 times the logarithm (base 10) of the
input power, referenced to a power level which is selected by pressing the REF key. The following
equation illustrates this relationship:
dB reading=10*lg[Net Applied Power/Net Referenced Power]
=10*lg{[(P-P
Z
)]/[(P
STOREF
-P
Z
)]}
P detector input power
P
STOREF
Absolute power value of reference light
P
Z
Background light power value in zero clearing
Measurment steps:
a)A
utomatically adjust the signal range and choose the wavelength
b)Shield the light source which you need to measure
c)Short press
and Remove the initial background signal. The data should be close to zero. But in
fact the data will be fluctuated because of the flux and the dark current of the detector.
d)Let the reference light shine in the detector .
e)Long press REF until the screen shows REL, keep down the reference signal power value PSTOREF
and enter the relative measuring mode.
f)Use the light which need to be measured shining in the detector.
g)Read out.
5.7 Saving and delete
You can long pressing “save” to store the wavelength, the upper and low limite of the power value and
the status of the attenuator. The last stored measurement condition still can be used after restarting.
There is no need for you to resetting. When you long press the “save”, the new data would be stored,
and it will replace the last stored data. If you do not store the measurment data, it will keep the
factory settings mode after restarting. Long pressing
(until a “beep” is heard) can delete all stored
data and go back to the factory settings mode.
5.8
Introductions for reseting
When replacing the different types of detector, if the header fails to identify, you can long press the
button
(until a “beep”is heard) to restore the factory settings.
Attention
The reference light source and the light source which you want to measure should measure in the same
condition. The background P
Z
should try to be consistent, to make sure the reference power and the
measured power bigger than P
Z
, otherwise the dB measurement is no practical meaning, and an Erro
message is indicated on the screen.