Swept Source Optical Coherence Tomography System

Features

• Real-Time Video Rate Imaging
• Simultaneous OCT and CCD Imaging
• 3D Volumetric Imaging and Surface Profiling
• Large Imaging Depth
• Available with Handheld Probe and "Microstand"
• Telecentric Scan Lenses
• New Doppler OCT Upgrade Options for Swept Source OCT Systems

Please select the Applications tab above for SS-OCT specific images, or visit our Image Gallery for up-to-date application data from all our imaging systems.

OCT Applications

• Biomedical Imaging and Real-Time Surgical Guidance
• Material Inspection
• Thin film Test and Measurement
• 3D Volumetric Imaging
• 3D Surface Profilometry

Thorlabs offers a family of Swept Source Optical Coherence Tomography (SS-OCT) systems. SS-OCT imaging provides high-resolution en-face and cross-sectional imaging of turbid media. Thorlabs' SS-OCT systems come complete and are ready for research and industrial applications. Our system is capable of high-speed 2D and 3D imaging of the internal structure, as well as surface profiling of the sample.

System Description

Swept Source OCT is a frequency domain OCT technique that measures the magnitude and time delay of reflected light in order to construct depth profiles
(A-scans) in the sample being imaged. Adjacent A-scans are then taken and all the images combined to create a 3D image. The design integrates a broadband, high-speed swept laser and a fiber-based Michelson interferometer with a balanced detection scheme. The multifunctional system includes an integrated CCD camera which provides simultaneous en-face and cross-sectional OCT imaging of the sample. The system includes a handheld probe that can be mounted onto an adjustable XYZ stage for a more stable imaging platform.

Advanced data acquisition and digital signal processing techniques are employed in the Swept Source OCT system to enable real-time video rate OCT imaging. Optical 3D volumetric imaging and surface profiling capabilities are included in the standard software. This OCT system can provide coherence gated en-face images similar to optical coherence microscopy and also enables the generation of images similar to confocal microscopy by summing signals in the axial direction. High-speed 3D OCT imaging provides comprehensive data that combines the advantages of surface microscopy and structural OCT imaging in a single system.

This system includes a swept source laser, imaging module, imaging probe, XYZ mounting stage, computer with data acquisition cards and pre-installed software, and all of the necessary electrical and optical cables needed for operation. An optional instrument cart (sold separately, OCM-CART) is available for easy lab setup. This cart includes workspace large enough for the microscope and computer screen, a sliding shelf for the keyboard and mouse, and shelves for the laser and computer.

An articulated probe mount (OCS-ARM) is also available as an optional accessory that allows imaging of larger objects and is suitable for industrial inspection applications.

Thorlabs OEM and Research Ready OCT Systems

Thorlabs swept source OCT systems are highly customizable. The basic OCT engine includes the swept light source, optional interferometer module, and the software development kit (SDK). Please see 'System Description' tab for more details.

The OCT engines are readily adapted to various industrial and biomedical applications. Customers can choose our standard probe or engineer application-specific probes, which may be directly interfaced with Thorlabs OCT systems.

Optical

Electrical

2D Cross-Sectional OCT Imaging Capability

2D en-face Microscope Imaging Capability

3D Volumetric Imaging Capability

System Description

As shown in Figure 1 below, Thorlabs' SS-OCT system incorporates a high-speed frequency swept external cavity laser (SL1325-P16), which has a 3 dB spectral bandwidth greater than 100 nm. The swept source has a built-in Mach-Zehnder Interferometer that provides the frequency clock for the laser. The main output of the laser is coupled into a fiber-based Michelson interferometer and split into the reference and sample arms using a broadband 50/50 coupler. In the reference arm of the interferometer, the light is reflected back into the fiber by a stationary mirror, and the reflectivity is controlled by a variable optical attenuator. In the sample arm, the light is fiber coupled into the imaging probe and focused onto the sample surface by a long working distance objective (LSM03).

The sample is placed on a stage, providing XY and rotational translation. An integrated CCD camera in the probe provides a conventional microscopic view of the sample, which aids sample alignment. A pair of XY galvo mirrors scans the beam across the sample surface, creating 1D, 2D, or 3D images.

Signal Processing
In the Thorlabs SS-OCT system, the interference signal is detected using a high-transimpedance gain balanced photodetector (PDB145C), which suppresses the DC and autocorrelation noise in the interference signals. A 14-bit high-speed digitizer is used to sample the OCT interference fringe signals, which are first converted from time to frequency space using a fast Fourier transform (FFT) and then recalibrated. The FFT of the interference signal yields the depth dependent reflectivity profile for the OCT image.

OCS Swept Source Software

The pre-installed SS-OCT software contains everything needed for system control, data acquisition, processing, and file management. The software provides flexible control of image size, brightness, contrast, and the A-line average.

The OCT data may be displayed in 2D or 3D mode. The software allows real-time recording of 2D or 3D data into disk files at full imaging speed. For the 3D imaging mode, the probe beam is sequentially scanned across the sample surface area, and the 3D volume data set under this area is acquired, processed, and stored. 3D volume rendering capability of the data is provided with the preinstalled Matlab software. This package includes sample scripts for standard data collection and file management, but is also user-customizable.

The recorded binary data files can be exported into standard image files (jpeg, bmp) or converted to movie files (avi). A software program that provides 3D graphics rendering of acquired OCT data is also provided in the software package.

GUI
The screen captures for three different imaging modes of the software GUI are shown in the figures below. In the 1D imaging mode, there is no transverse scanning of the probe beam in the sample arm. The recalibrated interference fringe signals and the Fourier transformed point spread functions are displayed in real-time, which aids optimization of the signal and system parameters. In the 2D imaging mode, the probe beam is scanned in one direction and cross-sectional OCT images are displayed in real-time.

Figure 1a (above) shows the 1D mode used for OCT interference fringe diagnosis.

Figure 1b (above) shows 2D mode for crossectional imaging

Figure 1c (above) shows the 3D volume imaging mode.

Sample SS-OCT Applications

Doppler Imaging Software

Thorlabs new Swept Source OCT System is now available with a Doppler Software upgrade to allow simultaneous OCT imaging with real-time flow monitoring, which is ideal for microfluidics, vascular or developmental biology studies.

Below we show a screen shot of the Doppler Softer user interface. Please see our Doppler Imaging Gallery for more details as well as sample data showing OCT structural information and blood flow measurements of a developing frog tadpole.