THORLABS VEG110 User manual

SS-OCT Base Unit
Swept Source OCT Systems:
VEGA series
User Manual

Original User Manual –not translated

Table of Contents
Chapter 1 Introduction............................................................................................................... 1
1.1. Safety ..................................................................................................................... 2
1.2. Care and Maintenance .......................................................................................... 3
Optical Cleaning..........................................................................................................4
Fiber Cleaning Techniques Using the FBC1...............................................................4
Service ........................................................................................................................5
Accessories and Customization..................................................................................5
Chapter 2 Setup .......................................................................................................................... 6
2.1. Unpacking ............................................................................................................. 6
2.2. System Connections ............................................................................................ 6
Base Unit Connections................................................................................................6
Internal Electrical Connections....................................................................................7
Electrical Interfaces to Probe......................................................................................7
2.3. Optical Interface to Probe .................................................................................... 7
2.4. System Installation ............................................................................................... 8
Chapter 3 Description .............................................................................................................. 15
3.1. Tutorial ................................................................................................................ 15
Theory.......................................................................................................................16
Thorlabs SS-OCT System Technology.....................................................................17
Nomenclature in OCT imaging..................................................................................19
3.2. SS-OCT Base Unit Components ........................................................................ 21
Base Unit...................................................................................................................21
PC with Graphical User Interface..............................................................................21
SDK...........................................................................................................................21
Imaging Scanner (Accessory)...................................................................................23
OCT-Stand (Accessory)............................................................................................25
Chapter 4 System Operation................................................................................................... 27
4.1. Starting the System ............................................................................................ 27
Turning ON the Imaging Module...............................................................................27
Turning ON the Laser Module...................................................................................27
Starting the Software.................................................................................................28
4.2. Basic Adjustments ............................................................................................. 28
Adjusting the Focus...................................................................................................28
Adjusting the Reference Length................................................................................29
Adjusting the Polarization..........................................................................................30
4.3. Advanced Adjustments ...................................................................................... 31
Focus and Choice of Objective Lens ........................................................................31
Imaging through Refractive Media............................................................................32
Reflecting Surfaces and Interfaces...........................................................................33
Rough Surfaces ........................................................................................................33
4.4. Shutting Down the System ................................................................................ 33
4.5. Example Images.................................................................................................. 34
Chapter 5 Imaging Artifacts..................................................................................................... 36
5.1. Saturation and Non-Linearity ............................................................................. 36
5.2. Multiple Scattering .............................................................................................. 37

5.3. Phase Wrapping and Fringe Washout ............................................................... 39
5.4. Flipped Image ..................................................................................................... 40
5.5. Shadowing .......................................................................................................... 41
5.6. Image Distortion by Refractive Media ............................................................... 42
The Group Refraction Index......................................................................................43
Measurement Depth in OCT Systems ......................................................................44
Distortions in the Image ............................................................................................45
Chapter 6 Troubleshooting...................................................................................................... 47
6.1. Changing the Input Fuses .................................................................................. 48
Chapter 7 Certifications and Compliance.............................................................................. 49
7.1. Declaration of Conformity Vega Series Base Units .......................................... 49
Chapter 8 Warranty................................................................................................................... 51
8.1. Lasers and Imaging Systems............................................................................. 51
8.2. Non-Warranty Repairs ........................................................................................ 51
8.3. Warranty Exclusions .......................................................................................... 51
Chapter 9 Specifications.......................................................................................................... 52
Chapter 10 Mechanical Drawings............................................................................................. 53
Chapter 11 Regulatory ............................................................................................................... 54
11.1. Waste Treatment is Your Own Responsibility .................................................. 54
11.2. Ecological Background ...................................................................................... 54
Chapter 12 Thorlabs Worldwide Contacts............................................................................... 55

SD-OCT Base Unit Chapter 1: Introduction
Rev A, March 3, 2017 Page 1
Chapter 1 Introduction
ATTENTION
Please read the instruction manual carefully before operating the SS-OCT system. All
statements regarding safety and technical specifications will only apply when the unit is
operated correctly.
This equipment is intended for laboratory use only and is not certified for medical applications,
including but not limited to life support situations.
Refer to this manual whenever the following symbols are encountered on the SS-OCT system:
Attention symbol indicates that additional information is given in this manual.
Laser Safety symbol indicates that laser radiation is present.
ATTENTION
Check the supply voltage of the system before plugging in the computer. Make sure the
included power cords for the base unit, computer, and monitor are connected to a properly
grounded outlet (100 –240 VAC; 50 –60 Hz).
Transportation and delivery may cause the SS-OCT system to be warm or cool upon receipt.
Please wait for the system to reach room temperature before attempting to operate.
Operate this system on a flat, dry, and stable surface only.
WARRANTY WARNING
Do not open the base unit, imaging scanner or PC. There are no user serviceable parts in this
product. Opening the device will void your warranty. Any modification or servicing of this
system by unqualified personnel renders Thorlabs free of any liability. This device can only be
returned when packed into the complete original packaging, including all foam packing inserts.
If necessary, ask for replacement packaging.

SD-OCT Base Unit Chapter 1: Introduction
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1.1. Safety
SHOCK WARNING –HIGH VOLTAGE
Before applying power to the system, make sure that the protective conductor of the three-
conductor mains power cord is correctly connected to the protective earth contact of the socket
outlet. Improper grounding can cause electrical shock resulting in severe injury or even death.
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.
ATTENTION
Do not obstruct the air-ventilation slots in the computer housing. Do not obstruct air-ventilation
into the bottom of the base unit or out of the exhaust fan on the rear of the unit.
Mobile telephones, cellular phones, or other radio transmitters are not to be used within the
range of three meters of this unit, since the electromagnetic field intensity may exceed the
maximum allowed disturbance values according to IEC 61000-6-1:2005.
The safety of any system incorporating the equipment is the responsibility of the assembler of
the system.
If equipment is used in a manner not specified by the manufacturer, the protection provided by
the equipment may be impaired.
LASER RADIATION WARNING
Laser emission may be emitted
a) from the scan lens of a scanner (intended use)
b) from the back of the base unit when the fiber cap is removed and the fiber disconnected
c) from the output of the fiber when the fiber is not connected to a scanner
Do not look into the optical output when the device is operating. The laser radiation is not
visible to the human eye and can cause serious damage to your eyesight.
The laser class information is also stated on the laser safety labels on the back of the housing.
Example given for class 1M LASER product:
INVISIBLE LASER RADIATION
DO NOT STARE INTO BEAM OR VIEW
DIRECTLY WITH OPTICAL INSTRUMENTS
CLASS 1M LASER PRODUCT
CLASSIFIED ACCORDING TO DIN EN 60825-1:2014

SD-OCT Base Unit Chapter 1: Introduction
Rev A, March 3, 2017 Page 3
1.2. Care and Maintenance
Handle the system with care during transportation and unpacking. Banging or dropping the system can damage
the unit or lower system performance. If the system is mishandled during shipment, the optical components
may become misaligned, which could lead to a decrease in image quality. If this occurs, the system will need
to be realigned by qualified personnel. Please contact Thorlabs technical support for more information.
Do not store or operate in a damp, closed environment.
Do not store or operate on surfaces that are susceptible to vibrations.
Do not expose to direct sunlight.
Do not use solvents on or near the equipment.
Keep away from dust, dirt, and air-borne pollutants (including cigarette smoke). The system is not
designed for outdoor use. Protect the equipment from rain, snow, and humidity.
Do not expose to mechanical and thermal extremes. Protect the equipment from rapid variation in
temperature.
Handle all connectors, both electrical and optical, with care. Do not use unnecessary force, as this may
damage the connectors.
Handle the optical fiber with care. Mechanical stress can decrease performance and potentially destroy
the fiber. Continual bending of the optical fiber can cause damage. It is important, therefore, to keep
the optical fiber patch cable as straight as possible to minimize bending.
Note: The most common cause of low signal intensity is contamination of the fiber due to airborne pollutants.
To minimize exposure, avoid unnecessarily disconnecting the optical fiber patch cable. In addition, it is
advisable to check the fiber before making other adjustments to the optical system, such as changing the focus
or optical path length. Be sure to check the patch cord for a loose connection, and make sure that the fiber is
kept as straight as possible.
All lasers, especially lasers with resonator cavities that are defined by mechanical tolerances, are delicate
precision instruments and must be handled accordingly. The SS-OCT system is designed to withstand normal
transportation and operating conditions. Do not move the system while it is connected and in operation.

SD-OCT Base Unit Chapter 1: Introduction
Page 4 MTN008437-D02
Optical Cleaning
Good performance and image quality of the OCT imaging system relies on clean optical connections.Whenever
using the Thorlabs OCT system, the following guidelines for optical fiber connection should be followed:
1) Always make sure that the light source is switched off when you clean the fiber.
2) Always inspect and clean the fiber end before plugging it into a receptacle.
3) Always cover the fiber end that is not in use with a fiber cap or dust protection cover.
The cleaning procedure sucess could be visualized using a fiber inspection scope
Figure 1 Fiber Inspection Scope FS201
Fiber Cleaning Techniques Using the FBC1
This section details how to clean fiber bulkheads and fiber connectors using the FBC1 one-step cleaner.
Using Extended Mode
Figure 2 FBC1 Extended Mode
To use extended mode, pull the tip outward while simultaneously pushing down on the lock button. Extended
mode is useful for panels with multiple bulkhead connectors or other tight spaces.

SD-OCT Base Unit Chapter 1: Introduction
Rev A, March 3, 2017 Page 5
Cleaning Fiber Bulkheads
Figure 3 Cleaning Fiber Bulkheads
Remove the guide cap completely from the device, and insert the tip of the cleaner into the bulkhead connector.
Push the case to start the cleaning process; a click indicates that the cleaning is complete.
Cleaning Fiber Connectors
Figure 4 Cleaning Fiber Connectors
Open the cover on the guide cap, and insert the fiber connector over the guide cap. Push the case to start the
cleaning process; a click indicates that the cleaning is complete.
Service
Only trained and approved Thorlabs personnel are allowed to service the system. Please contact Thorlabs
technical support for more information.
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 the accessories that Thorlabs provides. Any modification or maintenance
by unqualified personnel will render the warranty null and void, leaving Thorlabs free of liability. Please contact
Thorlabs technical support for questions on customization.

SD-OCT Base Unit Chapter 2: Setup
Page 6 MTN008437-D02
Chapter 2 Setup
2.1. Unpacking
Carefully unpack the components from the transport boxes. Make sure that all components are 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.
2.2. System Connections
Base Unit Connections
All of the base unit connections are located in the rear (see Figure 5)
Figure 5 Rear View of Base Unit
A. Power Plugs (Laser and Imaging Module)
B. VHDCI Data Port to connect to the NI PCIe-6351
C. Auxiliary Connection Port (LEMO, 14 Pin)
D. Probe Connection Port (LEMO, 19 Pin)
E. SMA Connector for SYNC TRIGGER to Connect to Alazar Tech. ATS9350
F. SMA Connector for OCT SIGNAL to Connect to Alazar Tech. ATS9350
G. Probe Fiber Receptacle (FC/APC)
H. Laser Input Fiber Receptacle (FC/APC)
I. USB Data Port to Connect PC (USB 2.0 Type B Interface)
J. Laser Output Fiber Receptacle (FC/APC)
K. SMA Connector for DAQ k-CLOCK to Connect to Alazar Tech. ATS9350
L. SMA Connectzor for DAQ SWEEP TRIGGER to Connect to Alazar Tech. 9350

SD-OCT Base Unit Chapter 2: Setup
Rev A, March 3, 2017 Page 7
Internal Electrical Connections
The USB connection to the PC is used for the control communication between the Software and Base Unit
(Imaging Module). The acquisition and synchronization of the spectral information is using the SYNC TRIGGER
connection.
Electrical Interfaces to Probe
For the connection to a scanner application there are two different interfaces available:
The probe connection port is intended to be used together with dedicated Thorlabs imaging scanners
OCTG and OCTP.
The auxiliary connection port is intended to be used together with dedicated Thorlabs imaging scanner
OCTH and furthermore allows the use of a custom scanner. It hosts two analogue signals for driving
separate actuators (e.g. Galvanometer scanner), communication lines and supply voltages.
Electrical Probe Connection Interfaces
Probe Connection Port
Lemo ECG.2B.319.CLL
Auxiliary Connection Port
Lemo ECA.1B.314.CLL
Table 1 Electrical Probe Connection Interface
Please contact Thorlabs’tech support for information regarding the pin configuration.
2.3. Optical Interface to Probe
The base unit incorporates one FC/APC fiber interface depending on the internal fiber architecture. If not
different due to customization the single mode fiber used in the base units is given in Table 2:
Optical Probe Connection Interface
Base Unit Series
Fiber Plug / Receptacle
Single Mode Fiber
Vega
FC/APC
Corning SMF28e+
Table 2 Optical Probe Connection Interface

SD-OCT Base Unit Chapter 2: Setup
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2.4. System Installation
ATTENTION
Make sure the included power cords for the base unit, computer and monitor are connected to a
properly grounded outlet (100 –240 VAC; 50 –60 Hz).
Transportation and delivery may cause the SD-OCT system to be warm or cool upon receipt.
Please wait for the system to reach room temperature before attempting to operate.
Operate this system on a flat, dry, and stable surface only.
1) Install the PC, monitor, mouse and keyboard according to the documentation provided by the PC
manufacturer.
2) If applicable, assemble the OCT-Stand as described in the documents provided in the OCT-Stand
box.
3) If applicable, mount the scanner in the OCT-Stand by sliding the dove tail at the back of the scanner
into the dove tail slide of the OCT-Stand.
Figure 6 Mounting the Scanner into the Dove Tail Slide of the OCT-Stand
4) Connect the CameraLink cable between the base unit and the PC
5) Attach the USB cable to the base unit and to the PC.
6) Connect the power supply plug to the socket of the base unit and connect the other end to a wall
plug.

SD-OCT Base Unit Chapter 2: Setup
Rev A, March 3, 2017 Page 9
7) Attach the electric connection cable to the imaging scanner.
Align the red dot of the plug to the alignment mark of the electric connection port of the scanner
(e.g.: OCTG).
Figure 7 Plugging the Electric Connector into the Scanner
Push the connector into the plug until you hear a “click” sound.
Figure 8 Electric Connector plugged into the Scanner

SD-OCT Base Unit Chapter 2: Setup
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8) Fiber connection to the imaging scanner
ATTENTION
When installing the fiber, make sure that the fiber tip does not get 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.
Figure 9 Fiber Connection to the Imaging Scanner
A) Slide the fiber tip into the center bore of the fiber connection.
B and C) The fiber needs to be oriented in rotation, so that the alignment nose slides into the mating
part of the probe connector as show in Figure 9 C.
NOTE: If the nose slide is not properly aligned, you will still be able to secure the fiber but
there will be significant light losses produced by this incorrect connection.
D) Secure the fiber connection by turning the lock cap clockwise. No force is needed for this
operation.
A
D
C
B

SD-OCT Base Unit Chapter 2: Setup
Rev A, March 3, 2017 Page 11
9) Attach the electric connection cable to the base unit
Align the red dot upwards, facing the alignment mark in the base unit.
Figure 10 Installing the Electric Connection Cable at the Base Unit
Push the connector into the plug until a “click” sound is heard.
10) Fiber connection to the base unit.
ATTENTION
When installing the fiber, make sure that the fiber tip does not get contaminated by dust.
Do not touch the fiber tip!
Remove the dust caps from the fiber end and from the FC/APC fiber connection at the base unit. The
fiber should be installed in a similar fashion as at the scanner. Follow the steps indicated in Figure 9
and pay attention not to touch the fiber tip.
ATTENTION
The fiber is slightly longer than the interconnection cable to avoid stress to it. Please be careful
not to pull the loop of the fiber at the back of the base unit!
Figure 11 Fiber Connection to the Base Unit

SD-OCT Base Unit Chapter 2: Setup
Page 12 MTN008437-D02
11) USB, Signal and Trigger connections at the Imaging Module (see Figure 12):
Attach the SMA cable labeled “OCT SIGNAL” to the respective SMA port at the Imaging Module
and make sure the connection is tight.
Attach the VHDCI cable to the respective port which is labeled “CONTROL”. Make sure both
fastening screws which are attached to the connector are bolted tightly.
Attach the SMA cable labeled “SYNC TRIGGER” to the respective SMA port at the Imaging
Module and make sure the connection is tight.
Connect the USB cable to the USB port and make sure the connection is tight.
Figure 12 Installation of the Electrical Connections at the Imaging Module
12) k-CLOCK and Trigger connections at the Laser Module (see Figure 13):
Attach the SMA cable labeled “DAQ SWEEP TRIGGER” to the respective SMA port at the Laser
Module and make sure the connection is tight.
Attach the SMA cable labeled “DAQ k-CLOCK” to the respective SMA port at the Laser Module
and again make sure that the connection is secured tightly.
Any other SMA ports at the Laser Module are not to be used. These are meant for monitoring
purposes only and should not be connected. These ports are capped when delivered. Similarly,
the USB port at the Laser Module is for service purposes only and must not be connected.
Figure 13 Installation of the Electrical Connections at the Laser Module

SD-OCT Base Unit Chapter 2: Setup
Rev A, March 3, 2017 Page 13
13) Connections at the DAQ cards (see Figure 14):
Identify both the Alazar ATS9350 DAQ card and the NI PCIe-6351 DAQ card at the back of the
PC (see Figure 14).
Connect the VHDCI cable to the NI PCIe-6351 DAQ card. Make sure both fastening screws which
are attached to the connector are bolted tightly.
Attach the k-CLOCK cable to the only available SMA port at the Alazar ATS9350 DAQ card. This
port and the respective cable are labeled “ECLK”. Make sure the connection is secured tightly.
Attach the BNC end of the cable labeled “DAQ SWEEP TRIGGER” / “TRIG IN” to the second
BNC port from the left marked as “TRIG IN”. Make sure the connection is secured tightly.
Attach the BNC end of the cable labeled “SYNC TRIGGER” / “AUX I/O” to the first BNC port from
the left marked as “AUX I/O”. Make sure the connection is secured tightly.
Attach the BNC end of the cable labeled “OCT SIGNAL” / “CH B” to the third BNC port of the
Alazar ATS9350 DAQ from the left marked as “CH B”. Again make sure the connection is secured
tightly.
The BNC port marked as CH A is not used!
Figure 14 Connections of the Alazar and NI DAQ Cards

SD-OCT Base Unit Chapter 2: Setup
Page 14 MTN008437-D02
14) Fiber connection between the Laser and Imaging Module:
Connect one end of the 1m long fiber to the Laser Module at the fiber port labeled “LASER APERTURE”
and the other end to the Imaging Module at the fiber port labeled “LASER IN” as indicated in Figure
15. When attaching the fiber, make sure the orientation is correct, otherwise there will be a
substantial loss in optical power transferred from the Laser into the Imaging Module!
Figure 15 Fiber Connection between the Laser and the Imaging Module
15) Removing the protective cap off the scan objective
Pull the protective cap off the scan objective. Do not rotate the protective cap, as this might loosen the
fit of the illumination tube. Do not touch the optical surface of the lens.
Figure 16 Protective Cap Removal

SD-OCT Base Unit Chapter 3: Description
Rev A, March 3, 2017 Page 15
Chapter 3 Description
3.1. Tutorial
Fourier Domain Optical Coherence Tomography (FD-OCT) is based on low-coherence interferometry, which
utilizes the coherent properties of a light source to measure optical path length delays in a sample.
To obtain cross-sectional images with micron-level resolution using OCT, an interferometer is set up to measure
optical path length differences between light reflected from the sample and reference arms.
There are two types of FD-OCT systems, each characterized by its light source and detection schemes:
Spatially encoded Frequency Domain OCT (SeFD-OCT) and time encoded Frequency Domain OCT (TeFD-
OCT), also named Swept Source OCT (SS-OCT). In both types of systems, light is divided by a fiber coupler
into the sample and reference arms of an interferometer setup.
Back reflected light, attributed to variations in the index of refraction within a sample, recouples into the sample
arm fiber and then combines with the light that has traveled a fixed optical path length along the reference arm.
The resulting interferogram is measured by either a spectrometer (SeFD-OCT) or balanced photodetectors
(SS-OCT).
The frequency of the interferogram measured by the sensor is related to the depth location of the reflector in
the sample. As a result, a depth reflectivity profile (A-scan) is produced by taking a Fourier transform of the
detected interferogram. 2D cross-sectional images (B-scans) are produced by scanning the OCT sample beam
across the sample; by doing so, a series of A-scans are collected to create the 2D image. Similarly, when the
OCT beam is scanned in a second direction, a series of 2D images is collected to produce a 3D volume dataset.
Figure 17 FD-OCT Signal Processing

SD-OCT Base Unit Chapter 3: Description
Page 16 MTN008437-D02
Theory
The interference equation for the cross correlated interference term is
      󰇛󰇜
With the phase difference  being a function of the optical path length difference and the wavenumber
    
This optical amplification of a small sample intensity with a strong reference intensity allows the detection of
single photons from the sample and is the key to the outstanding sensitivity of OCT.
Due to the reflective character of the measurement modality the optical path length difference is twice the
distances in the image. The maximum imaging depth, and so twice optical path length difference, is defined by
the wavenumber spacing of the acquisition .
 
  
In Full-Range OCT setups the image depth could be doubled
The signal width has two limits,
One limit for the signal width is given by the spectral distribution of the light source. For a fully used
light source being Gaussian shaped in the equation is:
   󰇛󰇜

with:
     
The other limitation for the signal width is given by the sampling. For a rectangular spectrum the FFT
results in a sinc function
    
with:
     

  
A light source is not shaped in a way that the autocorrelation function is clean normally. Therefore the shape
should be apodized to get a clean point spread function. A good compromise between resolution and side lobe
suppression could be a Hanning window showing a signal width of:
    
In real mesurements the signal width is furthermore limited by noise, dispersion mismatch between sample-
and reference arm of the interferometer, and optical path length distribution of the imaging caused by
aberration.