Basic Measurement Setup - THORLABS INT-COM-1300 Operation Manual

3.6 Basic Measurement Setup

This section is dedicated to INT-COM-1300 Common Path OCT Interferometer basic
setup in a swept source Fourier domain OCT system, see Figure
connected to 1300nm IN while an red aiming laser is connected to 660nm IN. OCT
fringe signals are recorded to a Data Acquisition Device connected to OUTPUT. A
common path interferometer probe is connected to PROBE and a variable optical
attenuator (VOA) is connected between VOA IN and VOA OUT.
Sample Sample
Probe Probe
VOA VOA VOA
The VOA is used to adjust for power balance at the balanced detector's inputs to
remove any DC component in the interference signal. Furthermore in balanced
condition maximum common mode rejection (maximum noise suppression) is
achieved. The VOA setting mainly depends on external Common Path probe loss
and sample reflectivity. The INT-COM-1300 is designed for low reflectivity samples.
For high reflectivity samples it could be necessary to attenuate the back reflected
probe light to achieve power balance at the balanced detector.
To obtain maximum noise suppression across the entire bandwidth of the balanced
detector, equal optical path lengths are also essential. Any path length imbalance will
introduce a phase shift between the two optical signals detected by the balanced
detector which will decrease noise reduction performance. The 95/5 TAP coupler
acts as signal divider for the balanced detection.
WDM WDM
Circulator Circulator
Slope Compensation Slope Compensation
INT-COM-1300 INT-COM-1300
Figure 9: Basic measurement setup
3 Detailed Description
. A swept laser is
9
95/5 95/5
INT-COM-1300 / page 13
Aiming Aiming
laser laser
OCT OCT
laser laser
Data Data Data
Acquisition Acquisition Acquisition
Device Device Device