Cerna® Birefringence Imaging Microscopes

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Side View of CM502 Microscope

Sam Tesfai
General Manager,

Thorlabs Imaging Systems

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Features

• Measures Sample Retardance Up to a Half-Wave at 633 nm (Up to 316 nm Retardance) and Azimuths (Fast Axis Orientation) Up to ±90°
• Spatial Resolution of 1.055 μm with Included 10X, 0.3 NA Objective
  • Additional Verified Accurate Objectives Sold Below
• Built-In 633 nm Light Source
• Two Configurations Available
  • Motorized Objective Arm (Microscope Item # CM502)
  • Manual Objective Arm (Microscope Item # CM501)  
• Custom Operating Wavelengths Available from 488 to 780 nm by Contacting Tech Support

Applications

• Stress-Induced Birefringence Imaging
• Birefringence Sensitive Tissue Analysis
• Dye-Free, Label-Free Imaging
• Structural Imaging
• Pathologic Diagnosis
• Material Research
• Quality Inspection

Thorlabs’ Cerna^® Birefringence Imaging Microscopes are complete systems for measuring the retardance and azimuth of birefringent materials. With retardance measurements as low as ±1 nm, azimuth measurements as small as ±1°, spatial resolution of 1.055 μm with the included objective, and the flexible Cerna platform, these microscopes are a versatile solution for birefringence imaging. The CM50x microscopes are designed for use in academic research, medical diagnostics, industrial manufacturing, and product quality assurance. Since the operation is based on a liquid crystal device, there is no internal mechanical movement, leading to very stable, vibration-free operation. Please see the Technique tab above for details on operation and examples of application data taken with these microscopes. 

The illumination wavelength of the systems offered below is 633 nm. This wavelength can be customized from 488 nm to 780 nm by contacting Tech Support. The system includes a standard objective with 10X magnification and measures retardance up to a half-wave at 633 nm (up to 316 nm retardance) and azimuths up to ±90°. The full specifications of these microscopes are outlined in the Specs tab.

The microscope body is built on the flexible Cerna platform with 95 mm dovetail for easy integration with the wide range of compatible sample holders or custom modules that use our Cerna body attachments to integrate components from our large catalog of optomechanics. The CSN1202 Nosepiece incorporated into the CM50x microscopes can also hold two objectives. Please refer to the Microscope Add-Ons tab above for recommendations on sample holders and objectives whose accuracy has been verified for these birefringence measurements. 

The CM50x microscope consists of a main microscope body, an LED illumination module, 10X Nikon objective, scientific grade CMOS camera, and either a motorized (Microscope Item # CM502) or manual (Microscope Item # CM501) focusing module. See the table to the right for a comparison the two configurations. The Shipping List tab above provides details on what comes with each configuration.

A Windows^®-based software package is included with the birefringence imaging microscope that contains every feature needed for system control and data acquisition. To view additional information about this system's software features and sample measurement results, please refer to the Software tab above.

These systems can be installed by the user and detailed instructions are provided in the CM50x manual. An overview of the assembly steps is shown in the Assembly tab above, and the Connections tab highlights all system connections. An optional installation service is available for customers at additional charge. Please contact Tech Support.

For applications requiring a larger field of view, our LCC7201B Birefringence Imaging System offers the same retardance and azimuth range and accuracy, but over a Ø20 mm field of view, and at a lower spatial resolution of 9.77 μm.

CM50x Microscope Specifications

CM502 Motorized Arm Specifications

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Optical Schematic of CM50x Birefringent Microscope

Birefringence Imaging

Polarized Light Microscopy
Polarized Light Microscopy provides high contrast images of birefringent materials and can be used for both qualitative and quantitative measurements of the retardance and azimuth of these materials. Standard polarized light microscopy requires two rotatable, crossed polarizers, a white light source, and an adjustable phase compensator. The first polarizer sets the polarization of light entering the sample and the second polarizer acts as an analyzer. Measurements of the retardance and the azimuth are accomplished by rotating the sample stage, adjusting the phase compensator, and recording the interference color. The quantitative retardance of the sample can be determined using a Michel-Levy color chart, and this path length difference can be converted to an index of refraction difference if the thickness of the sample is known. Conversely, if the index difference is known, this measurement can be used to determine thickness. Polarized light microscopy relies on multiple steps and can be time-consuming due to the need for a color camera, sample rotation, and phase compensator adjustment.

CM50x Microscope Advantages and Operation
The CM50x Cerna^® Birefringence Imaging Microscopes use polarimetry to provide quick and easy measurements of retardance and fast axis orientation of birefringent transparent materials without the need for sample rotation or a color camera. These measurements support research in fields such as industrial manufacturing, biology, and medicine. The microscope measures multiple intensity images recorded with various polarization states, which are precisely controlled by a liquid crystal module. Since there is no internal mechanical movement, these microscopes provide very stable, vibration-free operation.

A diagram of the system operation for the CM50x microscopes is shown at the right. An M625L4 Mounted LED in combination with a collimation lens and a previous-generation FL632.8-1 Filter provide a 633 nm collimated light source that is steered into the liquid crystal module by a WFA1000 Trans-Illumination Module. The liquid crystal module can set a number of different linear and circular input polarizations. The sample under test is placed at the focal plane of an included N10X-PF 10X objective (Nikon Plan Fluorite, 0.3 NA). Additional objectives with higher or lower NAs that have been verified to produce accurate birefringence measurements when used with the CM50x systems are also available. Please see recommendations in the Microscope Add-Ons tab above. A circular analyzer is set at the back focal plane of the objective to filter the transmitted light. A CS505MU Monochrome Scientific Camera records the intensity images for each sequential input state of polarization.

For details on system set up and general operation, please see the CM50x manual.

Applications
The CM50x Microscopes have applications in a variety of research and manufacturing fields. With the same retardance and azimuth range and accuracy as our LCC7201B Birefringence Imaging System, but higher spatial resolution of 1.055 μm with the included 10X objective compared to the 9.77 μm resolution of the LCC7201B system, these microscopes are a versatile solution to birefringence imaging.

Below, we show measurements of laser-induced birefringence in a polymer wave plate, stress-induced birefringence in an optical fiber, and several examples of birefringence in biological tissue. Click the tabs below for details. 

Laser-Induced Birefringence in a Polymer Wave Plate

Laser-Induced Birefringence Change in a Polymer Wave Plate
When a quartz or liquid crystal polymer wave plate is integrated into a system for a given application, the laser induced birefringence change, i.e., retardance and fast axis orientation (azimuth), can be critical. Since even a very slight change can create problems in practical applications, the verification of such changes is essential. 

The images below show retardance and azimuth measurements over an area of approximately 200 µm x 200 µm for a WPH10E-830 Liquid Crystal Polymer Zero-Order Wave Plate that had been damaged during laser-induced damage threshold (LIDT) testing. Because the damaged area, visible in the center of each image, has large changes in retardance, these measurements were taken using the Standard Retardance Range mode in the included software. When the retardance changes in the damaged region are small but still significant to performance, they can be difficult to measure with a standard polarized light microscope. Our CM50x microscopes are sensitive to retardance and azimuth changes as small as ±1 nm and ±1° when using the Low Retardance Range measurement mode, allowing for more subtle changes in performance to be identified during quality inspection. See the Software tab for more details on available measurement modes.

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2D Retardance View of a Liquid Crystal Polymer Waveplate

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2D Azimuth View of a Liquid Crystal Polymer Waveplate

Birefringence in Biological Tissue

The Cerna Birefringence Imaging Microscope is a powerful tool to reveal submicroscopic organization in biological materials. It offers rapid measurements to study and understand biological structures, such as striated muscle, nerve myelin, mitotic spindle, dermal collagen, and stress fibers, without staining or labeling. Some example measurements, covering the full field of 0.84 mm x 0.71 mm, are shown below. 

Berry Hair Whole Mount (w.m.) (Complete Organism)

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2D Retardance View of Berry Hair Whole Mount (w.m.)

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2D Azimuth View of Berry Hair Whole Mount (w.m.)

Dandelion Fuzz Whole Mount (w.m.) (Complete Organism)

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2D Retardance View of Dandelion Fuzz Whole Mount (w.m.)

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2D Azimuth View of Dandelion Fuzz Whole Mount (w.m.)

Leaf of Nerium Indicum T.S.

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2D Retardance View of Leaf of Nerium Indicum T.S.

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2D Azimuth View of Leaf of Nerium Indicum T.S.

Tomato Flesh Whole Mount (w.m.) (Complete Organism)

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2D Retardance View of Tomato Flesh Whole Mount (w.m.)

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2D Azimuth View of Tomato Flesh Whole Mount (w.m.)

Human Hair (w.m.) (Complete Organism)

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2D Retardance View of Human Hair (w.m.)

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2D Azimuth View of Human Hair (w.m.)

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CM502 Components

CM502 Cerna^® Birefringence Imaging Microscope, Motorized Objective Arm

Item # CM502 consists of:

• Main CM502 Microscope Body
• Camera Assembly
• LED Assembly
• 10X Objective (Item # N10X-PF)
• Birefringent 1951 USAF Test Target (Item # R3L1S1B)
• 12 VDC Power Supply (Item # DS12)
• Region-Specific Power Cord
• USB Drive with Software and Manual (Not Shown)
• USB 2.0 Type-A to Type-B Cable, 2 m
• USB 3.0 A to Micro B Cable, 3 m (Appearance May Vary from Photo)*
• Control Cable, 2 m
• Protective Tape for Shipping and Storage (Not Shown)
• CCHK/M Metric Hex Key Set (Not Shown)
• Three-Channel Controller for Motorized Rigid Stands and PLS Series Stages (Item # MCM301) which includes:
  • Controller Box
  • Power Supply, with Region-Specific Power Cord
  • USB Cable (A to B)
• 3-Knob USB HID Joystick (Item # MCMK3)

*The microscope performance specifications provided are guaranteed only with the provided USB 3.0 cable.

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CM501 Components

CM501 Cerna Birefringence Imaging Microscope, Manual Objective Arm

Item # CM501 consists of:

• Main CM501 Microscope Body
• Camera Assembly
• LED Assembly
• 10X Objective (Item # N10X-PF)
• Birefringent 1951 USAF Test Target (Item # R3L1S1B)
• 12 VDC Power Supply (Item # DS12)
• Region-Specific Power Cord
• USB Drive with Software and Manual (Not Shown)
• USB 2.0 Type-A to Type-B Cable, 2 m
• USB 3.0 A to Micro B Cable, 3 m (Appearance May Vary from Photo)*
• Control Cable, 2 m
• Protective Tape for Shipping and Storage (Not Shown)
• CCHK/M Metric Hex Key Set (Not Shown)

*The microscope performance specifications provided are guaranteed only with the provided USB 3.0 cable. 

Application-Optimized Cerna Microscopes

Developed in collaboration with our colleagues in the field, the Cerna microscopy platform is uniquely modular and flexible, making it adaptable to a wide range of demanding experimental requirements. If you would like to work with our application specialists, engineers, and sales team to design your own microscope, please email ImagingSales@thorlabs.com.

Selected Accessories

In order to image with the CM50x Birefringence Imaging Microscopes, it is necessary to add a sample holder. To that end, we have ensured that Cerna^® microscopes are compatible with a wide range of accessories. The information below compares some suggested Cerna-compatible components. For a comprehensive list of sample holders, please see our Sample Holders for DIY Cerna Systems.

The CSN1202 Nosepiece incorporated into the CM50x microscopes can hold two objectives. The systems come with an N10X-PF objective. Additional verified compatible objectives are listed below.

Content

• Verified Objectives
• Sample Holders

Verified Objectives

Item #	N4X-PF	N10X-PF	N20X-PF
Photo (Click to Enlarge)
Objective Class	Plan Fluorite
Magnificationa	4X	10X	20X
Numerical Aperture (NA)	0.13	0.3	0.50
Working Distance (WD)	17.2 mm	16 mm	2.1 mm
Parfocal Length	60 mm
Threading	M25 x 0.75

• When Used with the Design Tube Lens Focal Length of 200 mm

• CM50x Imaging Systems Directly Accept M25 x 0.75-Threaded Objectives (Nikon)
• Unverified Objectives Not Recommended

The CSN1202 nosepiece can hold two objectives with M25 x 0.75 threads, commonly used by Nikon objectives. One N10X-PF 10X, 0.3 NA objective is included with each CM50x microscope. Since high-NA optics contribute residual birefringence and might impact the system accuracy, we verified three widefield Nikon objectives, shown in the table to the right, to ensure that the system accuracy can still be guaranteed while switching the objectives. Unverified objectives may result in loss of measurement accuracy and are not recommended.

Please note that objectives with a magnification greater than 10X are not recommended for use with the CM501 Microscope with Manual Objective Arm, as the focusing resolution is not sufficient for these higher NA objectives.

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CM501 Microscope with
MLS203P2 Slide Holder,
MPRM(/M) Rectangular Insert Holder, MPP20 Post, and LPH200 Post Holder

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CM502 Microscope with CSA1051 Adapter Arm, CSS2001 Manual XY Stage, and CS2000 Slide Holder

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MLS203-1 Stage with MLS203P2 Slide Holder on CSA1000 Fixed Arm

Sample Holders

• Rigid Stands Hold Samples Underneath and Around the Objective
  • Designed for Slides, Petri Dishes, Well Plates, Recording Chambers, Micromanipulators, and Custom Inserts
  • Motorized and Manual Translation Stages with X and Y Travel Available
• Fixed Arms to Incorporate Fast XY Stage, Manual XY Stage, Lens Tubes, and/or Cage Systems to be Placed Directly into Optical Path
  • CSA1000: For Our MLS203-1 Fast XY Scanning Stage
  • CSA1051: For CSS2001 Olympus Manual Stage
  • CSA1001: For Ø1" Lens Tubes and 30 mm Cage Systems
  • CSA1002: For Ø2" Lens Tubes and 60 mm Cage Systems

Thorlabs offers highly configurable solutions for mounting your sample beneath the objective of the Cerna microscope. Rigid stands are available with multiple platform styles that can accept slides, petri dishes, recording chambers, and custom inserts. The included collar makes them lockable at a height and angle chosen by the user. An example rigid stand is shown at the right integrated with the CM501 Microscope. We also offer translation stages for these rigid stands that provide motorized horizontal translation of the sample.

Our fixed arms attach directly to the dovetail that spans the height of the microscope body, allowing them to be positioned anywhere along the body height, putting the sample directly into the microscope's optical path, and taking advantage of the existing footprint of the scope. For a pre-configured motorized sample holder solution, use the CSA1000 Fixed Arm with the MLS203-1 Fast XY Scanning Stage (shown in the left-most image above). This stage is compatible with our MZS500-E Piezo-Driven Insert, which adds high-resolution Z-axis adjustments. The CSA1051 Adapter Arm, paired with the CSS2001 Olympus Manual Stage and CSS2000 Olympus Slide Holder, provides a manual XY solution, shown in the center image above. Alternatively, the CSA1001 and CSA1002 Fixed Arms are compatible with Thorlabs' extensive selection of optomechanical components, allowing custom sample holder configurations to be integrated with this microscope.

Several compatible options are outlined in the tables below. For a comprehensive list of options, please see our Sample Holders for DIY Cerna Systems.

Rigid Stands

Click to Enlarge MPRM(/M) Rectangular Insert Holder, MPP20 Post, and LPH200 Post Holder Designed for Multiple Slides, Petri Dishes, Well Plates, Breadboards, Our MZS500-E Z-Axis Piezo Stage, and User-Designed Inserts Height Range: 248.1 - 410.1 mm Other Heights Available

Click to Enlarge MPRC(/M) Recording Chamber Holder, MPP25 Post, and LPH250 Post Holder Insert Designed for Recording Chambers Height Range: 301.3 - 514.2 mm Other Heights Available

Click to Enlarge MP20(/M) Rigid Stand with Platform 24 1/4"-20 (M6 x 1.0) Tapped Holes for Holding Micromanipulators or Other Equipment Height Range: 248.1 - 410.1 mm Other Heights Available

Fixed Arms

Click to Enlarge CSA1000 Fixed Arm Accepts MLS203-1 Fast XY Scanning Stage

Click to Enlarge CSA1051 Adapter Arm Compatible with CSS2001 Olympus U-SV Manual XY Stage

Click to Enlarge CSA1001 Fixed Arm Compatible with Ø1" Lens Tubes and 30 mm Cage Systems

Click to Enlarge CSA1002 Fixed Arm Compatible with Ø2" Lens Tubes and 60 mm Cage Systems

These microscope systems can be installed by the user and detailed instructions are provided in each manual. An optional installation service is available for these systems at additional charge. Please contact Tech Support for details.

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Step 1: Use both hands to transfer the main unit to the optical table using the holding points shown above. Always wear gloves when handling, setting up, and working with the system.

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Step 2: Mount the main unit onto the optical table using at least four screws, i.e., at least one screw at each corner.

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Step 3: Unscrew the two illumination module dust cover locking screws and remove the cover.

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Step 4: Connect the LED assembly using the four cage plate rods. Tighten the four locking screws on the illumination module to secure the cage rods to the main microscope body. 

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Step 5: Replace the illumination module dust cover and tighten the four locking screws in the CP33/M Cage Plate to secure the cage rods to the cage plate. 

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Step 6: Remove the green protective tape on the objective holder and install the N10X-PF Objective into the CSN1202 Nosepiece.

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Step 7: Loosen the locking screw on the front of the microscope, above the product label, with a 2 mm hex key and remove the dust cover on the camera port.

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Step 8: Put the camera assembly on the camera port and secure the camera assembly with the locking screw.

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Step 9: Final CM501 Microscope Assembly

CM50x Microscope Connections

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CM50x Camera Connections

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CM50x Control Box Connection

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CM50x Main Body Connections

CM502 Motorized Arm Controller Connections

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MCM301 Controller Front View
(Click for Back View)

Software

Version 2.2.11

Click the button below to visit the Cerna Birefringence Imaging Microscope software page.

The Cerna^® Birefringence Imaging Microscopes include a Windows^®-based software package with every feature needed for system control and data acquisition. Please click the Software button to the right to download the latest software for this system.

Features

• Standard and Low Noise Modes for Retardance and Azimuth Measurements
• Raw Sample Mode for Intensity Measurement
• Selectable Rectangular, Circular, or Polygon Region of Interest (ROI)
• Adjustable Dynamic Camera Settings (Gain, Exposure Time, Black Levels)
• Overexposure Detection
• Auto Adjustment of Light Source Level
• 1D, 2D, and 3D Measurement Result Displays
• Data Output in Binary, CSV, and Image (PNG and TIFF) Formats
• SDK for C++, LabVIEW™, and Python Programming Environments

The software includes three modes: Standard Mode and Low-Noise Mode, which are used to measure a sample's retardance and azimuth, and Raw Sample Mode, which is used to measure intensity with different input polarizations. Standard and Raw Sample Modes provide a higher measurement rate with a lower signal-to-noise ratio, while Low Noise Mode provides a lower measurement rate with a higher signal-to-noise ratio. An exposure time of 300 ms is set as the default, which allows a measurement to be finished within 20 seconds in Standard Mode and 4 minutes in Low Noise Mode.

The standard and low-noise modes provide two ranges of measurement accuracy: Standard Retardance Range and Low Retardance Range. Standard Retardance provides a measurement accuracy of ±10 nm for retardances in the 0 nm to 316 nm range and ±3° for azimuths over the entire measurement range. Low Retardance Range will improve the measurement accuracy to ±1 nm for retardances in the 0 nm to 100 nm range and ±1° for azimuths over the entire measurement range. The minimum exposure time is 0.021 ms, and the maximum exposure time is 7330 ms.

Below are screenshots from the included user interface, showing the different measurement display modes available. The Preview, 1D, 2D, and 3D views are all of a liquid crystal polymer zero-order half wave plate (Item # WPH10E-830).

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Azimuth and Retardance 1D View

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Camera Preview

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Retardance 3D View

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Retardance with Azimuth Vector 2D View