THORLABS OCT-LK Series, Руководство пользователя

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OCTP Series Scanner Chapter 5: Description
Rev F, November 03, 2018 Page 25
5.2. Optical Design
5.2.1. Common Path Setup (OCTP)
As shown below, the OCTP is factory-configured such that the sample beam and reference beam are generated
after the beam leaves the fiber. This allows us to use single-mode optical fiber to transport the beam into the
scanner while minimizing the use of free-space propagation.
This approach avoids problems that can degrade image quality, related to optical phenomena like polarization
mode dispersion (PMD) and birefringence, and makes the performance of the system independent from the
length of the single-mode fiber.
Figure 30 Diagram of the Common Path Setup
5.2.2. Dual Path Setup (OCTP-NR)
Shown below is an alternative beam geometry to the common path setup when the scanner is ordered in a
configuration without reference (OCTP-NR). The sample beam and reference beam are generated within
different fibers, before the beam exits into free space. In this configuration, the scanner becomes the sample
arm of the interferometer. By using two different fibers, the beamsplitter cube used in the common path setup
is no longer needed.The flexible cage compatible design of the OCTP allows the removal of the beamsplitter
cube and the reference module.
While this approach is able to provide greater sensitivity due to the absence of the beamsplitter cube (which
reduces the intensity of the light that returns to the fiber), it is significantly more sensitive to the optical
phenomena mentioned before. Please contact Thorlabs’ OCT support (see Chapter 11) for details.
Figure 31 Diagram of the Dual Path Setup