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SD-OCT Base Unit Chapter 3: Description
Page 18 MTN012389-D02
Thorlabs SD-OCT System Technology
SD-OCT is a measurement method based on the detection of optical path length differences within an
interferometer. The technology incorporates a broadband light source with a high-speed spectrometer to provide
depth profiles, acquired using a Fast Fourier Transform, that can be assembled into cross-sectional images.
These cross-sectional images can be used for 3-dimensional reconstructions.
The light of a broadband source travels to the sample and illuminates it perpendicularly and with a small focus
that provides a good lateral resolution. The back-scattered light travels to the spectrometer where the unique
phase delay for each wavelength is detected. To gain access to this back-scattered light, it is necessary to insert
a splitting device into the optical path. In Thorlabs' SD-OCT systems, this device could be either a fiber coupler
or a circulator.
The two main features of a 2-dimensional scanned image are the axial and lateral resolutions. The axial
resolution does not depend on the optics; it is driven by the used spectral bandwidth of the light source. The
lateral resolution, on the other hand, is affected by the chosen application optics.
The OCT system has three main parts: the base unit, a PC and a scanner with OCT-STAND. The schematic
setup of the SD-OCT system with coupler and circulator is shown in the figures below:
Figure 16 Schematic Diagram of a SD-OCT System with Internal Coupler
Figure 17 Schematic Diagram of a SD-OCT System with Internal Circulator