Noise-Eater Implementation - MOGlabs ARF021 Manual

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6.4 Noise-eater implementation

A common application for
which technical noise arising from power fluctuations in a laser beam.
Figure 6.1 shows a typical configuration, where the intensity of the
undiffracted (zero-order) beam is stabilised as seen in Figure 6.2.
In this configuration, the
attenuator, diffracting some of the light into the unused first-order
output. The transmitted optical power is measured with a photode-
tector, and the
ARF/XRF
Laser
Figure 6.1: Typical setup for optical power noise eater.
5
Photodetector signal
4
3
2
ARF/XRF input error signal
1
Figure 6.2: Photodetector signal (magneta) and conditioned error signal
(blue) before and after activating noise-eater feedback (simulated). Note
that the DC offset must be subtracted during signal conditioning.
Chapter 6. PID stabilisation
PID controllers is optical noise eating,
acts as a high-speed variable optical
AOM
controls the power in proportion to the
RF
Error
ARF/XRF
+
AOM
Beamsplitter
Time Time
O set
Photodetector
Stabilised
O set