OCTP Series Scanner
Chapter 4: Installation
Rev F, November 03, 2018
Page 23
4. To determine the polarization state in the reference arm, the light in the sample arm has to be blocked,
e.g. by removing any sample from under the objective. Make sure to either block the light completely or
to have a sufficiently large gap between the objective and the substrate.
5. Rotate the quarter-wave plate in the reference arm such that the spectra on both Camera 0 and Camera 1
overlap exactly. The corresponding spectra are shown in Figure 29 on the bottom.
Note that a good agreement between the two spectra can be obtained several times when rotating the
quarter-wave plate by a full 360°. However, the agreement between the spectra will vary slightly and the
quarter-wave plate should be rotated such that the agreement is best (at 22.5° with respect to the incident
linearly polarized light).
6. Once the adjustment is complete, tighten the screws of the quarter-wave plate mounts.
Figure 29 Spectral distribution on the two cameras during the adjustment of the sample beam (top)
and the reference beam (button)
