Tutorial; Definitions And Explanations; Console Specifications - THORLABS PM100USB Operation Manual

5.3 Tutorial

Content
Definitions and explanations: This section gives an overview on specifications,
their definitions and application to sensor families.
Calculations: Here common formulas are given - power, energy and densities can
be calculated based on different given parameters.

5.3.1 Definitions and explanations

In this section the key parameters of Thorlabs Power Meters and Sensors are
commented.

5.3.1.1 Console Specifications

·
Measurement Ranges
It is important to keep in mind, that the optical power (energy) measurement is
based on a current measurement (photodiode sensors) or on a voltage meas-
urement (thermal and pyroelectric sensors). That's why the measurement
ranges are stated sensor dependent - for photodiode sensors are stated the
current ranges, for thermal and energy sensors - voltage ranges.
·
Display Resolution
Note:
The resolution is the minimum detectable change of power (energy), it is not
the minimum measurable power (energy)!
As the console measures a current or a voltage, the display resolution can be
stated only in A or V. In the specifications the resolution is stated for the most
sensitive measurement range. The optical power resolution depends on the ac-
tual sensor's responsivity.
Current input (photodiode sensors): The resolution is specified to "1 pA / re-
sponsivity value (A/W)". This means, that the PM100USB has in the lowest
measurement range (50 nA) a resolution of 1 pA. The responsivity of a photo
diode sensor is wavelength dependent, thus the power resolution is wavelength
dependent as well.
Example: A S120C sensor has a responsivity of 7.35 × 10
and 5.05 × 10
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power resolution is at 930 nm
and at 455 nm
© 2017 Thorlabs
A/W at 455 nm. In the lowest measurement range the displayed
5 Appendix
A/W at 930 nm,
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