THORLABS OTM211 User manual

OTM211
Optical Tweezer System
User Guide

Table of Contents
Chapter 1Warning Symbol Definitions..............................................................................................3
Chapter 2Safety....................................................................................................................................4
Chapter 3Description...........................................................................................................................5
3.1.Introduction .....................................................................................................................5
3.2.Theory ..............................................................................................................................5
3.3.Key System Features......................................................................................................6
3.4.System Components.......................................................................................................7
3.5.Optics Module..................................................................................................................8
3.6.Power Supply and Electronic Module ...........................................................................9
3.7.Interlock System..............................................................................................................9
Chapter 4Operation.............................................................................................................................10
4.1.Starting the System.......................................................................................................10
4.2.Graphical User Interface...............................................................................................10
4.3.SDK.................................................................................................................................11
Chapter 5Operating Conditions and Environmental Requirements............................................12
5.1.Selecting a Suitable Operation Environment .............................................................12
Chapter 6System Connections and Care.........................................................................................13
6.1.Module Connections.....................................................................................................13
6.1.1.Cable Descriptions .............................................................................................................. 13
6.2.Service............................................................................................................................14
6.3.Accessories and Customization..................................................................................14
Chapter 7Specifications.....................................................................................................................15
7.1.Laser Specifications .....................................................................................................15
7.2.Power Requirements.....................................................................................................15
7.3.Dimensions and Weights..............................................................................................15
Chapter 8Regulatory...........................................................................................................................16
8.1.Waste Treatment is Your Own Responsibility............................................................16
8.2.Ecological Background ................................................................................................16
Chapter 9Thorlabs Worldwide Contacts..........................................................................................17

OTM211 Chapter 1: Warning Symbol Definitions
Rev A, October 7, 2015 Page 3
Chapter 1 Warning Symbol Definitions
Below is a list of warning symbols you may encounter in this manual or on your device.
Symbol Description
Direct Current
Alternating Current
Both Direct and Alternating Current
Earth Ground Terminal
Protective Conductor Terminal
Frame or Chassis Terminal
Equipotentiality
On (Supply)
Off (Supply)
In Position of a Bi-Stable Push Control
Out Position of a Bi-Stable Push Control
Caution: Risk of Electric Shock
Caution: Hot Surface
Caution: Risk of Danger
Warning: Laser Radiation
Caution: Spinning Blades May Cause Harm

OTM211 Chapter 2: Safety
Rev A, October 7, 2015 Page 4
Chapter 2 Safety
All statements regarding safety of operation and technical data in this instruction manual will only
apply when the unit is operated correctly.
SHOCK WARNING
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 serious personal injury or death.
Ensure that the line voltage switch is set correctly for your local supply and that the appropriate
fuses are installed. Fuses should only be changed by qualified service personnel.
The OTM211 contains no user-serviceable parts. Do not operate without cover installed.
Refer all maintenance to suitably qualified personnel.
Contact Thorlabs for assistance.
CAUTION
Do not obstruct the unit’s air ventilation slots and fan outlets.
WARNING
This equipment contains a high power infrared laser. Radiations from this laser are not visible to the
human eye and can cause serious damage to your eyesight.
All laser radiation is enclosed during normal operation.
Do not attempt to defeat interlocks.
! !
LASER PRODUCT
CLASS 1

OTM211 Chapter 3: Description
Rev A, October 7, 2015 Page 5
Chapter 3 Description
3.1. Introduction
The Thorlabs OTM211 is an optical tweezers system designed for inverted microscopes. It provides two
independent trapping beams that allow the manipulation of nano- and micro particles. Each path can be used to
create several additional traps. The system is completely computer controlled and offers a graphical user interface
which provides the user with a set of tools for the most common trapping experiments. The detector module included
in the OTM211 allows users to perform quantitative force measurements and particle tracking. The included
Software Development Kit enables users to easily create applications optimized for their specific needs and allows
integration into more complex setups.
The OTM211 system integrates with existing imaging modalities, such as fluorescence, Raman, confocal, phase
contrast. Further on the system is compatible with all major microscope platforms.
3.2. Theory
Optical Tweezers, or traps as they are often called, are created by using a high numerical aperture objective to
tightly focus a laser beam thereby creating a spot where a dielectric particle with dimensions of the order of 0.3µm
to a few microns will experience a force due to transfer of momentum from the scattering of photons.
Arthur Ashkin in the early 1970s originally demonstrated that optical forces can manipulate micron-sized dielectric
particles in water (
Ashkin et al, Optics Letters, Vol 11, No. 5, may 1986 ). This technique has become an
important tool in a wide range of fields such as bioengineering, material science, and physics due to their ability to
hold and manipulate micron-sized particles and to measure forces in the piconewton and femtonewton ranges.
Figure 1 Theory of Optical Trapping
The capability of optical tweezers to exert measurable forces on dielectric particles offers a unique and valuable
tool for studying cell components such as biological proteins and molecular motors. In many investigations, optical
tweezers apply force to functionalized microspheres that have been attached to molecules of interest. Optical
tweezers apply a force toward the focus of the trapping laser beam with a magnitude proportional to the distance
of the particle from the focus, for small displacements from the center of the trap. This allows the optical tweezers
to be modeled by Hooke’s law, F= -kd, where d is the displacement from the center of the trap and k is the force
constant. As the laser beam passes through a trapped particle, it will be deflected by an amount that depends on
the position of the particle. Accurate force measurements depend on precise calibration of the spring constant, k,
and the particle position which varies with laser power and particle properties.
Three methods for ascertaining the force constant, k are: Equipartition, PSD Rolloff and Stokes’ drag. Since each
method relies on a different physical principle, the combined results provide a convenient way to verify the
calibration.

OTM211 Chapter 3: Description
Rev A, October 7, 2015 Page 6
The Equipartation method equates the average potential energy of the particle in the trap to the thermal energy of
the solvent molecules. In this method, a sample of particle positions is obtained by recording the position detector
output over time and converting the voltages to distances using the detector responsivity. For PSD roll off, the power
spectral density of a time series of trapped particle positions is computed and fitted to the response of a harmonic
oscillator with known damping due to the viscosity of the solvent. In the Stokes method, the sample is translated in
a range of velocities. A force balance between viscous drag on the particle and the trap force is computed.
3.3. Key System Features
 Multiple traps with computer control
 Force Measurement Capability
 Software user interface with enhanced mouse control of multiple time shared traps
 Multiple trap pattern creation with arbitrary spacing – circles, lines, rectangles
 IR laser with independent power control
 Two independent trap paths with multiple time-shared traps per path
 Active intensity stabilization of each trap beam with integrated noise eaters
 Concurrent standard microscopy techniques like fluorescence
 Compatible with major inverted microscope platforms
 Fully enclosed beam path – Class 1 certified
 Galvo-scanning beam control
 SDK package

OTM211 Chapter 3: Description
Rev A, October 7, 2015 Page 7
3.4. System Components
The OTM211 includes the following modules:
 Optics Module
 1.3NA Trapping Objective and Condenser
 1600 x 1200 CCD Camera with Imaging Adapter
 Electronics Control Module
 Power Supply Module
 Nikon Eclipse Ti-S Inverted Microscope with high resolution XYZ Piezo Stage
 Force Module
 Computer with Monitor and Accessories
Figure 2 Modules of Complete OTM211 System
Optics Module
Electronics
Control Module
Force Module
Safety Interlocks
Microscope
Stage Controller
Power Supply
Module

OTM211 Chapter 3: Description
Rev A, October 7, 2015 Page 8
3.5. Optics Module
The optics module includes all the optical and opto-electronic components for creating and controlling multiple
optical traps. The conditioned output beam is coupled into the microscope. A schematic for this module is shown
below.
Figure 3 Schematic of Optics Module

OTM211 Chapter 3: Description
Rev A, October 7, 2015 Page 9
3.6. Power Supply and Electronic Module
These two modules provide power and contain the control circuitry for the components in the optics module. The
rear panel of the power supply module has connection to the mains power supply and to the electronics module.
The front panel has an LED indicator when power is ON.
Figure 4 Power Supply Module Front Panel
The Electronics module houses the laser source . The rear panel has the interfaces for all cable connections to the
optics and power supply modules. The bottom right of the front panel of the electronics control module has a key
and an emergency shut-off switch for the laser. Three LEDs at the top are used to indicate main power, PC
connection, and USB data transfer.
Figure 5 Electronic Module Front Panel
3.7. Interlock System
For user safety, the system has four interlocks. There is the illumination pillar interlock, the viewport interlock,
sample cover interlock. Additionally a remote interlock connection is provided for user integration. All four interlocks
must be closed for laser emission.
The system is classified as a Class 1 laser.
Figure 6 Interlock System: (left) Viewport (and (right) Sample Cover
Laser Key and
indicator
Emergency
shutoff

OTM211 Chapter 4: Operation
Rev A, October 7, 2015 Page 10
Chapter 4 Operation
4.1. Starting the System
To power up the OTM211 system, follow the steps below.
1. Start the Power Supply Module by placing the POWER switch on the back of the unit to the “I” position.
Verify that the “POWER ON” indicator turns green on the lower front side of the unit.
2. At this time, the “Power” and “Ready” indicators on the Electronics Control Module will turn on.
3. Turn the key switch on the Electronics Module to the “ON” position.
4. Check the emergency stop button and make sure it is in the “Enable” position.
5. Make sure all interlocks are closed.
4.2. Graphical User Interface
The OTM211 system comes with a pre-installed software which contains everything needed for system control and
data acquisition. In addition an SDK is provided to allow users to easily create applications optimized for their
particular requirements.
The GUI has five main areas:
 The Camera Display
 The Laser Control
 The Stage Control
 The Trap Control
 Tools
Figure 7 OTM211 Software User Interface

OTM211 Chapter 4: Operation
Rev A, October 7, 2015 Page 11
The main screen of the software contains two areas: the video image acquired from the camera on the left side and
controls for the system on the right side. The control sections consist of four segments: Laser, Stage, and Trap
Control as well as Tools.
In a typical trapping application a user will trap a particle by positioning the trap either by clicking on the camera
image or by using the adjuster buttons in the trap control section. Which trap is currently selected is indicated in the
drop-down list. If a new trap is added the currently selected beam path (A or B) will be used to add another time-
share trap location. The position of the new trap can be set by clicking on the camera image. The tool section allows
the user to select information which will be display for the traps on the camera display, such as the trap label and
position.
The speed and step size for the trap movement are adjustable and can be optimized, e.g. when switching between
different objectives.
The analysis tools depend on the system configuration and provide access to e.g. force spectroscopy measurement
or particle tracking.
Figure 8 OTM211 GUI Showing Controls
4.3. SDK
The OTM211 Tweezers System is supplied with a software development kit (SDK). The SDK gives access to all
features of the instrument, thus enabling the creation of custom, application-specific software. The SDK is provided
as a 64 Bit Windows dynamic link library (dll). Language bindings for C, National Instruments LabView and C# are
available. For details, please refer to the OTM211 Programmer’s Reference Manual.

OTM211 Chapter 5: Operating Conditions and Environmental Requirements
Rev A, October 7, 2015 Page 12
Chapter 5 Operating Conditions and Environmental
Requirements
The system will be installed by a member of the Thorlabs team. In preparation for install, the following considerations
should be taken into account.
5.1. Selecting a Suitable Operation Environment
In order to deliver optimal performance we recommend installing the OTM211 Optical Tweezers System on an
actively vibration-damped surface. Thorlabs offers a variety of vibration-damped optical tables and microscopy
workstations. Please contact Thorlabs Technical Support for detailed information.
The following guidelines should be considered when installing the system:
 Do not store or operate in damp, condensing environments
 Do not expose to direct sunlight
 Do not use solvent on or near the equipment
 Keep away from dust, dirt, and air-borne pollutants
 The system is not designed for outdoor use. Protect from rain, snow, and humidity
 Do not expose the system to mechanical or thermal extremes. Protect the equipment from rapid variation
in temperature
 Handle all connectors and wiring 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. We suggest keeping the optical fiber as
straight as possible and maximizing bend radii.
 The OTM211 optical tweezers system is a precision instrument and must be handled accordingly. If the
system needs to be moved to a new location, please contact the Thorlabs team prior to doing so.

OTM211 Chapter 6: System Connections and Care
Rev A, October 7, 2015 Page 13
Chapter 6 System Connections and Care
6.1. Module Connections
The figure below shows the schematic for the rear panel connections for the optics, electronics, and power supply
modules.
Figure 9 Schematic of Rear Panel Connections
6.1.1. Cable Descriptions
 1: Shutter
 2: Fiber
 3-6: Galvos
 7-8: Laser Power Control
 9: Power Cable for active Laser stabilization
 10: USB to computer
 11: Electronics Module Power Supply
 12: Interlock Cable to Microscope
The Shutter Control cable, NE Power Out, USB, Laser Control 1 and 2, Galvo Controls cables (A, B, C and D)
for all four scanners) are labeled on the Optics Module Connecting Cable Bundle. The Ext. DAQ Connection is
reserved for custom applications.
Power
Laser Control
Galvo Control
Shutter Control
Laser
A
12
C
BD
Galvo Controls
Laser Control
Power In
Shutter Control Ext. DAQ Power Out
USB
Interlock
Max. 300W +/-15VDC
Max. 150W +15VDC
Max. 150W +12VDC
Laser
A
12
B
CD
INT INT
DC Power Out
115 - 230VAC, 50 - 60Hz
900 VA Max.
Fuse: 240V 5A / 110V 10A
To Mains
USB to Computer
Interlock to
Microscope
1
2
6
7
8
10
11
9
3
4
5
12

OTM211 Chapter 6: System Connections and Care
Rev A, October 7, 2015 Page 14
6.2. Service
Only trained Thorlabs personnel are allowed to open any of the modules to service the system. Please contact
Thorlabs Technical Support for more information.
6.3. Accessories and Customization
The Thorlabs OTM211 Microscope Tweezers System can be offered in several configurations, e.g. different
wavelength, optical power levels, integrated with additional imaging modalities.
To achieve the listed specifications the 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.

OTM211 Chapter 7: Specifications
Rev A, October 7, 2015 Page 15
Chapter 7 Specifications
7.1. Laser Specifications
Laser Specifications
Center Wavelength 1064 nm
Emission Bandwidth (FWHM) <0.25 nm
Output Power (before split) 5 W
Fiber Panda 980
Polarization State Linear
Output Power instabilities (rms) <0.2%
Output Beam Shape Gaussian, with M2 <1.1
7.2. Power Requirements
Power Specifications
Voltage 120 – 240 V
Maximum Power Consumption 1000 VA
7.3. Dimensions and Weights
Dimensions and Weights
Dimensions Weight
Optics Module 17" x 8" x 19"
(432 mm x 204 mm x 483 mm) 40 lbs (18 kg)
Electronics Module 17" x 15" x 10"
(432 mm x 381 mm x 254 mm) 20 lbs (9 kg)
Power Supply Module 17" x 13" x 9"
(432 mm x 331 mm x 229 mm) 40 lbs (18 kg)
Piezo Stage Controller 17.7" x 3.5" x 13.5"
(450 mm x 88 mm x 343 mm) 17.5 lbs (7.9 kg)

OTM211 Chapter 8: Regulatory
Rev A, October 7, 2015 Page 16
Chapter 8 Regulatory
As required by the WEEE (Waste Electrical and Electronic Equipment Directive) of the European Community and
the corresponding national laws, Thorlabs offers all end users in the EC the possibility to return “end of life” units
without incurring disposal charges.
 This offer is valid for Thorlabs electrical and electronic equipment:
 Sold after August 13, 2005
 Marked correspondingly with the crossed out “wheelie bin” logo (see right)
 Sold to a company or institute within the EC
 Currently owned by a company or institute within the EC
 Still complete, not disassembled and not contaminated
As the WEEE directive applies to self-contained operational electrical and electronic products, this end of life take
back service does not refer to other Thorlabs products, such as:
 Pure OEM products, that means assemblies to be built into a unit by the user (e. g. OEM laser driver cards)
 Components
 Mechanics and optics
 Left over parts of units disassembled by the user (PCB’s, housings etc.).
If you wish to return a Thorlabs unit for waste recovery, please contact Thorlabs or your nearest dealer for further
information.
8.1. Waste Treatment is Your Own Responsibility
If you do not return an “end of life” unit to Thorlabs, you must hand it to a company specialized in waste recovery.
Do not dispose of the unit in a litter bin or at a public waste disposal site.
8.2. Ecological Background
It is well known that WEEE pollutes the environment by releasing toxic products during decomposition. The aim of
the European RoHS directive is to reduce the content of toxic substances in electronic products in the future.
The intent of the WEEE directive is to enforce the recycling of WEEE. A controlled recycling of end of life products
will thereby avoid negative impacts on the environment.
Wheelie Bin Logo

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Chapter Thorlabs Worldwide Contacts
USA, Canada, and South America
Thorlabs, Inc.
56 Sparta Avenue
Newton, NJ 07860
USA
Tel: [phone]
Fax: [phone]
www.thorlabs.com
www.thorlabs.us (West Coast)
Email: [e-mail]
Support: [e-mail]
UK and Ireland
Thorlabs Ltd.
1 Saint Thomas Place
Ely CB7 4EX
Great Britain
Tel: [phone]
Fax: [phone]
www.thorlabs.com
Email: [e-mail]
Support: [e-mail]
Europe
Thorlabs GmbH
Hans-Böckler-Str. 6
85221 Dachau / Munich
Germany
Tel: [phone]
Fax: [phone]
www.thorlabs.de
Email: [email protected]om
Scandinavia
Thorlabs Sweden AB
Bergfotsgatan 7
431 35 Mölndal
Sweden
Tel: [phone]
Fax: [phone]
www.thorlabs.com
Email: [e-mail]
France
Thorlabs SAS
109, rue des Côtes
78600 Maisons-Laffitte
France
Tel: [phone]
Fax: [phone]
www.thorlabs.com
Email: [e-mail]
Brazil
Thorlabs Vendas de Fotônicos Ltda.
Rua Riachuelo, 171
São Carlos, SP 13560-110
Brazil
Tel: [phone]
Fax: [phone]
www.thorlabs.com
Email: [email protected]
Japan
Thorlabs Japan, Inc.
3-6-3 Kitamachi,
Nerima-ku, Tokyo 179-0081
Japan
Tel: [phone]
Fax: [phone]
www.thorlabs.co.jp
Email: [e-mail]
China
Thorlabs China
Room A101, No. 100, Lane 2891,
South Qilianshan Road
Putuo District
Shanghai 200331
China
Tel: [phone]
Fax: [phone]
www.thorlabschina.cn
Email: [email protected]

www.thorlabs.com