Optical Input; Electrical Output - THORLABS PDA8A2 Abbreviated Operation Manual

3 Operating Instruction

3.4.1 Optical Input

For maximum linearity performance when measuring focused beams, fiber outputs, or small
2
diameter beams, do not exceed a maximum intensity of 10 mW/cm .
Note
For optical alignment, use an optical input power below the saturation power while observing
the output voltage on a low-frequency measurement device such as a digital voltmeter.
Use external neutral density filters to reduce the input light level in order to stay below the
maximum output voltage.
The PDA8A2 housing features internal SM05 and external SM1 threads for convenient moun-
ting of lens tubes or cage systems.

3.4.2 Electrical Output

Thorlabs PDA8A2 photodetectors deliver an OUTPUT voltage that is a function of incident light
Â
P
power , the detector's responsivity (l) at a given wavelength, and the transimpedance
opt
G
gain :
Â
The detector's responsivity (l) for a given wavelength can be read from the spectral
responsivity curve (see Appendix ).
8
The maximum output of the PDA8A2 is 3.6 V for high-impedance loads and 1.8 V for 50 W
loads. The output signal should be below the maximum output voltage to avoid saturation.
© 2022 Thorlabs GmbH 5