Chapter 4: Operation
23155-D02, Rev A
Page 4
ring (included with the PDA30B) inside the 1” threaded coupler before
installing the fiber adapter.
7. Apply a light source to the detector. Adjust the gain to the desired
setting.
Caution!
The PDA30B was designed to allow maximum accessibility to the
photodetector by having the front surface of the diode flush with the
outside of the PDA housing. When using fiber adapters, make sure that the
fiber ferrule does not crash into the detector. Failure to do so may cause
damage to the diode and or the fiber. An easy way to accomplish this is to
install a SM1RR retaining ring (included with the PDA30B) inside the 1"
threaded coupler before installing the fiber adapter
Chapter 4 Operation
4.1. Theory of Operation
Thorlabs PDA series are ideal for measuring both pulsed and CW light sources.
The PDA30B includes a reverse-biased PIN photo diode, mated to a switchable
gain transimpedance amplifier, and packaged in a rugged housing.
4.2. Responsivity
The responsivity of a photodiode can be defined as a ratio of generated
photocurrent (I
PD
) to the incident light power (P) at a given wavelength:
=
Photodetector
Transimpedance Amp
Out
Feedback
R
F
A
B
-V
BNC
GND
GND
GND
R
LOAD
!
!
