THORLABS Telesto Series User Manual
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THORLABS Telesto Series User Manual

Spectral-domain oct system base units
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Telesto® and Ganymede™ Series
Spectral-Domain OCT System
Base Units
User Guide

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  • Page 1 Telesto® and Ganymede™ Series Spectral-Domain OCT System Base Units User Guide...

  • Page 2: Table Of Contents

    Using the Analog Input Feature ........................18 Chapter 3 Description ......................19 3.1.1 Theory ................................20 3.1.2 Thorlabs SD-OCT System Technology ....................... 21 3.1.3 Polarization-Sensitive Optical Coherence Tomography ................22 3.1.4 Nomenclature in OCT Imaging ........................23 3.2.1 Base Unit ................................. 24 3.2.2...
  • Page 3 Chapter 5 Imaging Artifacts ....................41 5.8.1 The Group Refractive Index .......................... 49 5.8.2 Measurement Depth in OCT Systems ......................50 5.8.3 Distortions in the Image ..........................51 Chapter 6 Sample Applications ....................53 Chapter 7 Troubleshooting ..................... 55 Chapter 8 Specifications ......................
  • Page 4 SD-OCT Base Units Chapter 12 Thorlabs OCT Support Contact ................74 Chapter 13 Thorlabs Worldwide Contacts ................75...

  • Page 5: Chapter 1 Introduction

    The laser safety symbol indicates that laser radiation is present. This manual describes the SD-OCT base units of the Telesto® and Ganymede™ Series. If not otherwise specified, the base units of the Telesto-PS Series are included in the Telesto Series. Attention Check the supply voltage of the system before plugging in the computer.
  • Page 6 Make sure that the line voltage rating agrees with your local supply and that the appropriate fuses are installed. Fuses should only be changed by qualified service personnel. Contact Thorlabs for assistance. Do not operate without cover installed. Refer servicing to qualified personnel.
  • Page 7 If the system is mishandled during shipment, the optical components may become misaligned, which can lead to a decrease in image quality. If this occurs, the system will need to be realigned by qualified personnel. Please contact Thorlabs’ OCT support (Chapter 12) for more information. •...

  • Page 8: Optical Cleaning

    Fiber bulkheads and connectors can be cleaned using the FBC250 2.5 mm Fiber Bulkhead and Connector Cleaner. This fiber cleaner features an extended mode, which is useful for panels with multiple bulkhead connectors or other tight spaces. For detailed cleaning procedures, please see the FBC250 manual on the Thorlabs website. Figure 2...

  • Page 9: Service

    SD-OCT Base Units Chapter 1: Introduction 1.2.3 Service Only trained and approved Thorlabs personnel are qualified to service the system. Please contact Thorlabs’ OCT support (Chapter 12) for more information. 1.2.4 Accessories and Customization The OCT base unit can easily be adapted for custom interfaces. To achieve the listed specifications, however, this system should only be used with accessories provided by Thorlabs.

  • Page 10: Chapter 2 Setup

    SD-OCT Base Units Chapter 2: Setup Chapter 2 Setup Unpacking Carefully unpack the components from the transport boxes. Make sure that all components have been delivered according to the packing list included in the transport box. After unpacking, store the packing cartons and inserts. You may need them in case of a service or upgrade of your OCT system.

  • Page 11: Base Unit Connections

    SD-OCT Base Units Chapter 2: Setup System Connections 2.2.1 Base Unit Connections All OCT base unit connections are located on the back of the device. Figure 3 Top: Possible Connections on the Back of the TELx21 OCT Base Units Middle: Possible Connections on the Back of the TEL4y1 and TEL5y1 OCT Base Units Bottom: Possible Connections on the back of the Ganymede Series OCT Base Units Rev.

  • Page 12: Internal Electrical Connections

    • • The OCTH Scanner connection port allows the use of a custom scanner or one of Thorlabs’ previous- generation handheld scanners. It hosts two analog signals for driving separate actuators (e.g. galvanometer scanners), as well as communication lines and supply voltages.
  • Page 13 SD-OCT Base Units Chapter 2: Setup Optical Interface to Scanner The Ganymede and Telesto base units incorporate an FC/APC fiber interface (see also section 3.1.2). The Telesto- PS Series base units come with an attached polarization maintaining fiber; no additional fiber is required. The table below lists the single mode fiber types used with the different base units (fiber types in customized systems may differ).
  • Page 14 SD-OCT Base Units Chapter 2: Setup Dovetail Focus Block Mounting Adapter Figure 4 A Schematic Showing an OCTG Scanner Being Mounted to the Dovetail Slide of an OCT-STAND 4. For GAN111 and GAN3x2: Connect the USB 3.0 cable between the A0 Camera connector on the base unit and the PC. Note: Make sure to use the USB 3.0 cable and to connect the cable to a USB 3.0 port, check for the blue color to confirm that the cable and port are for USB 3.0.
  • Page 15 SD-OCT Base Units Chapter 2: Setup Figure 5 Connection of the SMA-Dual Sub-D Cable to Both Frame-Grabber Cards (Telesto-PS Series Base Units Only) 5. Attach the USB 2.0 cable (I in Figure 3) to the base unit and to the PC. 6.
  • Page 16 SD-OCT Base Units Chapter 2: Setup Figure 7 Electrical Connector Plugged into the Scanner Push the connector into the receptacle until you hear a “click” sound, indicating that the connector is locked. Page 12 MTN026082-D02...
  • Page 17 SD-OCT Base Units Chapter 2: Setup 9. Connect the fiber to the imaging scanner. Attention When installing the fiber, make sure that the fiber tip is not contaminated by dust. Do not touch the fiber tip. Remove the dust caps from one fiber end and from the FC/APC fiber connection at the imaging scanner. Store these with the system packaging.
  • Page 18 SD-OCT Base Units Chapter 2: Setup 10. Attach the electric connection cable to the base unit. Use the Galvo Scanner port for OCTG and OCTP series scanners. Align the red dot upwards, facing the alignment mark in the base unit. Alignment Mark Red Dot Figure 9...
  • Page 19 SD-OCT Base Units Chapter 2: Setup 11. Connect the fiber to the base unit. (Not required in Telesto-PS series base units.) Remove the dust caps from the fiber end and from the FC/APC fiber connector on the base unit. Inspect the fiber and clean it according to Section 1.2.2. Attention When installing the fiber, make sure that the fiber tip is not contaminated by dust.

  • Page 20: Enable External Trigger

    SD-OCT Base Units Chapter 2: Setup 12. Pull the protective cap off the scan objective. Do not touch the optical surface of the lens. Figure 11 Protective Cap 2.4.1 Enable External Trigger To enable the use of an external A-scan trigger, a trigger cable from the external source must be connected to the Trigger port with a tee connector.

  • Page 21: Using The Trigger I/O Feature

    If the input/output impedance of the connected device cannot be adjusted, use an additional 50 Ω feedthrough terminator in line with the coaxial cable (Thorlabs Part Number T4119). Figure 13 SMA Cable Connected to Trigger I/O Port Rev.

  • Page 22: Using The Analog Input Feature

    SD-OCT Base Units Chapter 2: Setup 2.4.3 Using the Analog Input Feature The SD-OCT base units are capable of sampling up to two individual analog signals synchronously with the OCT imaging process. The Analog IN 1 and Analog IN 2 SMA connectors on the back panel are configured to receive analog input.

  • Page 23: Chapter 3 Description

    • (FD-OCT) and Spectral Domain OCT (SD-OCT). Thorlabs uses the abbreviations SD-OCT for our spatially encoded camera-based OCT systems and SS-OCT for our time-encoded systems. In both types of systems, a fiber coupler splits light into the sample and reference arms of an interferometer setup.

  • Page 24: Theory

    SD-OCT Base Units Chapter 3: Description 3.1.1 Theory The interference equation for the cross-correlated interference term is ���� ~2 ∙ � ���� ∙ ���� ∙ cos (Δ����) ���� ���� ���������������������������������������� �������������������� ���� ������������������������������������ With the phase difference (Δ����) being a function of the optical path length difference Δz and the wavenumber k Δ����...

  • Page 25: Thorlabs Sd-Oct System Technology

    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 is either a fiber coupler or a circulator.

  • Page 26: Polarization-Sensitive Optical Coherence Tomography

    SD-OCT Base Units Chapter 3: Description 3.1.3 Polarization-Sensitive Optical Coherence Tomography A standard OCT system is constructs a depth scan of the sample using the phase and intensity of the backscattered light from different positions in depth. Nevertheless, it does not account for polarization effects or birefringence in the sample, which might be interesting if the sample shows different birefringent properties locally.

  • Page 27: Nomenclature In Oct Imaging

    SD-OCT Base Units Chapter 3: Description In order to be sensitive to all polarization effects introduced by the sample and to be independent of the sample orientation in plane, the sample is probed with circularly polarized light. To obtain circularly polarized light, another QWP is placed in the sample arm which is turned by 45°...

  • Page 28: Base Unit

    Neither a scanner nor the OCT-STAND are included in the base unit package and must be ordered separately, or as part of a complete OCT system. When ordered together with a scanner, the system will be pre-assembled at Thorlabs and the PC settings will already be calibrated and optimized for the delivered OCT scanner.

  • Page 29: Pc With Graphical User Interface

    PC with Graphical User Interface Our OCT base units ship with application software made for the imaging scanners provided by Thorlabs. All required data analysis as well as 2D and 3D display can be performed within the ThorImage®OCT software. Data can be stored, analyzed, and exported for further use.

  • Page 30: Imaging Scanner (Accessory)

    3.2.4 Imaging Scanner (Accessory) Thorlabs’ SD-OCT systems use a common-path OCT setup in which the interferometer is located within the imaging scanner. This integration of the interferometer eliminates the problems associated with chromatic or polarization mode dispersion that are introduced by differences between individual fibers in the sample and reference arms.
  • Page 31 SD-OCT Base Units Chapter 3: Description Reference Arm Length Adjustment Quarter-Wave Plates Figure 23 OCTP-PS Series User-Customizable Scanner Rev. E, December 4, 2023 Page 27...

  • Page 32: Oct-Stand (Accessory)

    SD-OCT Base Units Chapter 3: Description 3.2.5 OCT-STAND (Accessory) The Thorlabs OCTG and OCTP scanners can be mounted to an OCT-STAND. The OCT-XYR1 rotation and translation stage is available as a common accessory to the OCT-STAND. Coarse Focus Adjustment Dovetail Slide...
  • Page 33 SD-OCT Base Units Chapter 3: Description Translation Adjusters Figure 26 OCT-XYR1 Sample Translation and Rotation Stage For further details on the OCT-STAND and the OCT-XYR1 stage, please refer to the Thorlabs website Rev. E, December 4, 2023 Page 29...

  • Page 34: Chapter 4 System Operation

    SD-OCT Base Units Chapter 4: System Operation Chapter 4 System Operation Starting the System Follow these steps for proper initialization of the system: 1. Verify that all connections between the PC and the OCT Base Unit are safe and secure (Chapter 2) and switch the PC on.

  • Page 35: Adjusting The Focus

    Basic Adjustments Upon receiving a complete SD-OCT system from Thorlabs, the reference length is pre-adjusted so that OCT imaging in air is possible simply by adjusting the focus to the region of interest. If the reference arm length no longer matches the sample arm length, the following procedure will aid you to a good basic adjustment.

  • Page 36: Adjusting The Reference Length

    SD-OCT Base Units Chapter 4: System Operation 4.2.3 Adjusting the Reference Length The following steps will guide you to a basic adjustment of the reference length: Start B-scan acquisition. When significantly misadjusted, you will get an incorrect OCT image or no image •...
  • Page 37 SD-OCT Base Units Chapter 4: System Operation Figure 31 B-Scan of a Fingerprint Out of Focus (Left) and In Focus (Right) One or more of the following features are characteristic for the sample being in focus: Sharp (thin) features in lateral direction •...

  • Page 38: Focus And Choice Of Objective Lens

    OCT B-Scans of Scattering Particles Using OCT-LK2 (Left), OCT-LK3, and OCT-LK4 (Right) Lenses Thorlabs offers three scan lens kits for different purposes. Figure 32 shows the difference in lateral resolution and depth of focus for the OCT-LK2 (high resolution imaging), OCT-LK3 (general purpose), and OCT-LK4 (long depth of focus) objectives.

  • Page 39: Imaging Through Refractive Media

    Thorlabs offers a special reference arm adapter to further increase the reference arm length; please contact Thorlabs’ OCT support (Chapter 12) for more information.

  • Page 40: Optimizing The Sensitivity

    SD-OCT Base Units Chapter 4: System Operation 4.3.3 Optimizing the Sensitivity In Frequency Domain OCT systems, a decrease in sensitivity is observed at larger measurement depths. This is especially obvious in SD-OCT systems where this so-called roll-off already starts to affect measurements at around 30% of the maximum measurement depth.

  • Page 41: Reflecting Surfaces And Interfaces

    (e.g. a glass slide) to reduce scattering. Thorlabs offers sample z-spacers that provide a glass plate at a fixed distance to reduce scattering effects and to keep the sample in focus. Please contact Thorlabs’ OCT support (Chapter 12) for more information.
  • Page 42 SD-OCT Base Units Chapter 4: System Operation Example Images Frequency Domain OCT can be used for a wide range of real-time monitoring applications in biological and clinical fields as well as in manufacturing and materials science. This technology is ideal for in-line industrial imaging applications ranging from laminated packaging films to 3D visualization of mechanical parts.
  • Page 43 SD-OCT Base Units Chapter 4: System Operation Material Imaging SD-OCT can also be used for non-biological materials science applications. SD-OCT systems are ideal for monitoring surface topography and layered structures. Figure 39 B-Scan of a Semi-Transparent Molded Plastic Cap Figure 40 B-Scan of a Laminated IR Viewing Card Figure 41 B-Scan of Plastic (Top: Intensity-Based Image;...
  • Page 44 SD-OCT Base Units Chapter 4: System Operation Biological Imaging Figure 42 B-Scan of a Section of a Grape Figure 43 B-Scan of a Carious Tooth (Top: Intensity-Based Image; Bottom: Degree of Polarization Uniformity (DOPU) PS-OCT Image) Page 40 MTN026082-D02...

  • Page 45: Chapter 5 Imaging Artifacts

    SD-OCT Base Units Chapter 5: Imaging Artifacts Chapter 5 Imaging Artifacts Saturation and Non-Linearity OCT A-scan data is created by frequency analysis of the spectral data generated by the spectrometer. Intense reflection from the sample can saturate the sensor of the spectrometer or illuminate very close to saturation. This effect broadens the signal and leads to a nonlinear response.
  • Page 46 SD-OCT Base Units Chapter 5: Imaging Artifacts Wrong Reference Intensity Setting The OCT image is created by interferometry as shown in Figure 15. For good image acquisition, the intensity of the reference light needs to be well above noise level and well below saturation. In the OCT software, a colored bar indicates if the reference intensity is set properly.
  • Page 47 SD-OCT Base Units Chapter 5: Imaging Artifacts Autocorrelation The fundamental principle of SD-OCT is a frequency analysis of an interference signal entering the spectrometer. Usually, this interference signal is created by photons returned from the sample interfering with photons returned from the reference arm.
  • Page 48 SD-OCT Base Units Chapter 5: Imaging Artifacts Multiple Scattering Imaging highly scattering material means that a large portion of the photons returned to the detection system have been scattered multiple times between entering and exiting the sample. Since OCT visualizes the relative travelled path lengths of photons, signals from multiple scattered photons appear to be deeper in the image than is physically true.
  • Page 49 SD-OCT Base Units Chapter 5: Imaging Artifacts Phase Wrapping and Fringe Washout Because A-scans are taken sequentially, they can encode time information as well as spatial information. Motion of the sample or parts of the sample in the direction of the optical axis can be determined by comparing the phase information from adjacent A-scans.
  • Page 50 SD-OCT Base Units Chapter 5: Imaging Artifacts Flipped Image OCT does not distinguish between photons that have traveled a distance ∆d shorter or longer than reference arm length. When the reference length is too long, the image will appear flipped. Surface Volume Figure 52...
  • Page 51 SD-OCT Base Units Chapter 5: Imaging Artifacts Shadowing Since SD-OCT imaging uses light for detection of depth information, this information can only be gleaned from photons exiting and reentering through the sampling aperture. Reflections, strong scattering, and absorption lead to shadows in the depth distribution of the acquired data. Figure 54 Rendered Volume of a Screw on an IR Viewing Card Displaying Shadowing Rev.
  • Page 52 SD-OCT Base Units Chapter 5: Imaging Artifacts Image Distortion by Refractive Media OCT images display path length differences in between reference arm length and sample arm length. These path lengths are optical path lengths, calculated from the physical path length multiplied by the group refractive index. See the images below for a schematic sample setup and the resulting OCT image that demonstrates the effect of nonuniform group refractive index across the sample.

  • Page 53: The Group Refractive Index

    SD-OCT Base Units Chapter 5: Imaging Artifacts 5.8.1 The Group Refractive Index The principle of optical coherence tomography is the detection of optical path length differences between the two arms of an interferometer. The mechanical path lengths and the refractive indices of the materials define the optical paths within these arms.

  • Page 54: Measurement Depth In Oct Systems

    SD-OCT Base Units Chapter 5: Imaging Artifacts 5.8.2 Measurement Depth in OCT Systems The spectral resolution of a frequency-domain OCT system defines its possible measurement depth. This depth is the maximum detectable optical path length difference, limited by the Nyquist criterion. In real materials, the measurement depth of OCT systems is reduced and the axial resolution is enhanced.

  • Page 55: Distortions In The Image

    SD-OCT Base Units Chapter 5: Imaging Artifacts 5.8.3 Distortions in the Image In complex structures, distortions can occur in the OCT image, which require a close look to be understood. Figure 58 Different Material Composition Across One Scan The loss of imaging depth depends on the amount of material through which the beam passes. As a result, the measured depth in the sample changes across the scan.
  • Page 56 SD-OCT Base Units Chapter 5: Imaging Artifacts As an example, a material with a wedge is analyzed: Figure 59 OCT Image of a Complex Structure The block shows “standard” behavior on the right side where the surface is perpendicular to the incoming beam. In the chamfered area there is diffraction and the beam travels under an angle through the block.

  • Page 57: Chapter 6 Sample Applications

    We employed this idea to image a solution of fluorophore ATTO-647N with a Telesto Series OCT system. Using a Ganymede series system instead would require different optical components due to its different center wavelength.
  • Page 58 Instead, a coupler and a separate reference arm were added to the scheme in Figure 60. Please contact for details of this setup. oct@thorlabs.com Raw OCT signal with color-coded Raw OCT signal...

  • Page 59: Chapter 7 Troubleshooting

    Focus is Out of Imaging Area Focus Reference Intensity too High or Adjust Reference Intensity too Low Other Reason Contact Thorlabs OCT Support Please refer to Chapter 12 for Thorlabs OCT Support contact information. Rev. E, December 4, 2023 Page 55...
  • Page 60 Please Refer to the ThorImage®OCT While Running a Slow 2D Scanner Calibration Wrong Software Manual for the Scanner Scan) Calibration Procedure Other Reason Contact Thorlabs OCT Support Please refer to Chapter 12 for Thorlabs OCT Support contact info. Page 56 MTN026082-D02...
  • Page 61 SD-OCT Base Units Chapter 7: Troubleshooting Changing the Input Fuses If for some reason you need to replace an open fuse in the base unit, you must perform the following procedure: 1. Remove the AC input cable that may be connected to the unit. 2.

  • Page 62: Chapter 8 Specifications

    SD-OCT Base Units Chapter 8: Specifications Chapter 8 Specifications General Specifications – SD-OCT Base Unit Supply Voltage for Base Unit 100 VAC - 240 VAC Maximum Power Consumption 150 W Weight Base Unit 12.5 kg Storage/Operating Temperature 10 °C to 35 °C Maximum Relative Humidity 85%, Non-Condensing Environment Dimensions of Base Unit (L x W x H)
  • Page 63 SD-OCT Base Units Chapter 8: Specifications Optical Performance Specifications – Telesto Series Base Unit Base Unit TEL211PS TEL221 TEL221PS TEL321 TEL411 TEL511 Center Wavelength 1325 nm 1300 nm 1300 nm 1315 nm 1315 nm 10 kHz to 2 kHz to...

  • Page 64: Chapter 9 Mechanical Drawing

    SD-OCT Base Units Chapter 9: Mechanical Drawing Chapter 9 Mechanical Drawing Figure 64 The unit pictured is TEL321, but the housing dimensions are the same for all base units. Page 60 MTN026082-D02...

  • Page 65: Chapter 10 Certifications And Compliance

    SD-OCT Base Units Chapter 10: Certifications and Compliance Chapter 10 Certifications and Compliance Declaration of Conformity for GAN111 Base Unit Rev. E, December 4, 2023 Page 61...
  • Page 66 SD-OCT Base Units Chapter 10: Certifications and Compliance Declaration of Conformity for GAN111C1 Imaging System Page 62 MTN026082-D02...
  • Page 67 SD-OCT Base Units Chapter 10: Certifications and Compliance Declaration of Conformity for GAN3x2 Base Units Rev. E, December 4, 2023 Page 63...
  • Page 68 SD-OCT Base Units Chapter 10: Certifications and Compliance Declaration of Conformity for GAN3x2C1 Imaging Systems Page 64 MTN026082-D02...
  • Page 69 SD-OCT Base Units Chapter 10: Certifications and Compliance Declaration of Conformity for GAN6x2 Base Units Rev. E, December 4, 2023 Page 65...
  • Page 70 SD-OCT Base Units Chapter 10: Certifications and Compliance Declaration of Conformity for GAN6x2C1 Imaging Systems Page 66 MTN026082-D02...
  • Page 71 SD-OCT Base Units Chapter 10: Certifications and Compliance Declaration of Conformity for TEL2x1(PS) Base Units Rev. E, December 4, 2023 Page 67...
  • Page 72 SD-OCT Base Units Chapter 10: Certifications and Compliance Declaration of Conformity for TEL2x1(PS)C1 Imaging Systems Page 68 MTN026082-D02...
  • Page 73 SD-OCT Base Units Chapter 10: Certifications and Compliance Declaration of Conformity for TEL3x1 Base Units Rev. E, December 4, 2023 Page 69...
  • Page 74 SD-OCT Base Units Chapter 10: Certifications and Compliance Declaration of Conformity for TEL3x1C1 Imaging Systems Page 70 MTN026082-D02...
  • Page 75 SD-OCT Base Units Chapter 10: Certifications and Compliance Declaration of Conformity for TEL411 Base Unit and TEL411C1 Imaging Systems Rev. E, December 4, 2023 Page 71...
  • Page 76 SD-OCT Base Units Chapter 10: Certifications and Compliance Declaration of Conformity for TEL511 Base Unit and TEL511C1 Imaging Systems Page 72 MTN026082-D02...

  • Page 77: Chapter 11 Warranty And Rma Information

    Waste treatment is your own responsibility. “End of life” units must be returned to Thorlabs or handed to a company specializing in waste recovery. Do not dispose of the unit in a litter bin or at a public waste disposal site. It is the user’s responsibility to delete all private data stored on the device prior to disposal.
  • Page 78 SD-OCT Base Units Chapter 12: Thorlabs OCT Support Contact Chapter 12 Thorlabs OCT Support Contact If you have a technical question or issue related to one of Thorlabs’ OCT products, please contact the OCT Support team located in Luebeck, Germany. OCT Support Thorlabs GmbH Maria-Goeppert-Straße 9...
  • Page 79 SD-OCT Base Units Chapter 13: Thorlabs Worldwide Contacts Chapter 13 Thorlabs Worldwide Contacts For technical support or sales inquiries, please visit us at for our most up-to-date www.thorlabs.com/contact contact information. USA, Canada, and South America UK and Ireland Thorlabs, Inc.
  • Page 80 www.thorlabs.com...

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