Mounting - THORLABS PDB48*C-AC series Operation Manual

P and P
opt,1 opt,2
G - transimpedance gain of the RF output
The responsivity  ( l ) for a given wavelength can be read from the individual curves in section
Technical Data to estimate the RF OUTPUT voltage. Please note that the given responsivity
curves represent typical values - individual responsivity may deviate.
The maximum RF OUTPUT power is typically + 18 dBm at 1 dB compression. To explain that:
An ideal amplifier would be a linear device - it's gain is constant at any input power level. In
reality, the output power of the amplifier is limited (e.g. by supply voltage). That means, with in-
creased input power the amplifier becomes saturated. Before the saturation is reached, a re-
duction in gain takes place - the result is a compression effect. The 1 dB compression point is
defined as the output power where the gain is 1 dB less than the small signal gain.
In order to avoid saturation, the output signal level should not exceed this 1-dB-compression
point.
MONITOR Outputs
The signal monitor outputs (MONITOR+ and MONITOR-) allow observation of the input power
level and can be used as individual power indicators. These outputs can also be used to meas-
ure RF (up to 3 MHz) modulated signals on each detector separately. The maximum output
voltage swing of the MONITOR output is +10 V for high impedance loads (+1.5 V into 50 W).
Saturation of MONITOR outputs will occur at optical input power level greater than 1 mW, de-
pending on the detector's wavelength response.
The amplifier offset voltage is factory set to zero at 23°C ambient temperature. A small drift dur-
ing a short warm-up period (~5min) may occur. For exact DC light level measurements a con-
stant temperature environment is recommended.

3.4 Mounting

The PDB48xC-AC is housed in a rugged shielded aluminum enclosure.
For post mounting an adapter can be attached to the bottom or side surface using four M2x8
screws (see below). This adapter supports #8-32 as well as M4 post mounts. The M4 tread is
marked.
© 2019 Thorlabs
- optical input power
3 Operating Instruction
7