OCTP Series Scanner
Chapter 4: Installation
Page 22
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from the reference arm is linearly polarized light rotated by 45° with respect to the light going into the OCTP-PS.
That way it is able to interfere with both polarization axes.
The polarization state in both arms can be adjusted by unlocking the screw of the quarter-wave plate mounts,
as shown in Figure 28. Note that the polarization state of the light of each arm is traversed twice through the
corresponding quarter-wave plate.
Please note that changing the orientation of the collimator and hence also that of the polarization maintaining
fiber, requires a readjustment of the quarter-wave plates detailed below.
Figure 28 Polarization Adjustment by Quarter-Wave Plates in OCTP-PS
ATTENTION
The quarter-wave plates are adjusted in both arms with respect to the orientation of the
polarization axis of the optical fiber (key aligned to slow axis) in the collimator. All positions are
marked in red.
In this configuration the main intensity from the sample arm is collected on Camera 0. If this is
NOT the case, please check if the CameraLink cables are interchanged.
The OCTP-PS comes prealigned and further alignment should not be necessary. Perform the following steps
only when you are certain that realignment is necessary. When using the OCTP-PS together with a Telesto PS-
Series OCT system, the polarization adjustment can be performed by following these steps:
1. Start ThorImage
®
OCT software and select the 1D Mode to display the intensity spectra of the two
cameras.
2. To detect the polarization state of the sample arm the reference arm has to be blocked, e.g. by closing
the zero-aperture iris.
3. Place a mirror in the focus of the sample arm. Rotate the quarter-wave plate such that the intensity on
Camera 0 is maximum and the intensity on Camera 1 is minimum. The corresponding spectra are shown
in Figure 29 on the top.
