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Infinity-Corrected Tube Lenses
Widefield Tube Lens,
Laser Scanning Tube Lens,
Widefield Tube Lens, f = 180 mm, 400 - 750 nm
Laser Scanning Tube Lens,
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Widefield imaging tube lenses take the collimated light from an infinity-corrected microscope and focus it onto a camera, as shown on the left. Laser scanning tube lenses can be used in telecentric systems to scan a laser spot across a sample.
These infinity-corrected tube lenses are designed for use with infinity-corrected objectives from all major manufacturers, including the Dry, Oil Immersion, and Physiology microscope objectives sold by Thorlabs. Designed for high-resolution imaging, biomedical, machine vision, and laser scanning applications, these lenses can be aligned in pairs to create relays, combined with objectives to create different effective magnification ratios at a scientific camera, used as drop-in replacements for tube lenses in existing systems, or integrated into DIY Cerna® Microscopes and other home-built microscopy setups to generate high-quality images.
Standard Widefield Tube Lenses
Telecentric Tube Lenses for Laser Scanning and Widefield Imaging
Our standard widefield tube lenses can also be used for laser scanning purposes when paired with the CLS-SL Visible Scan Lens, for example. However, using a standard tube lens in a scanning configuration will limit the unvignetted field size, since the tube lens must be placed at the telecentric pupil distance from the objective (e.g., 250 mm for the TTL200 lens), rather than the intended pupil distance of the tube lens.
Microscope and Objective Compatibility
Tube Lenses for Widefield Imaging
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This schematic shows the working distance and pupil distance for the TTL series and ITL200 tube lenses. The working distance corresponds to the distance from the top surface of the housing to the image plane. The pupil distance, defined as the distance between the bottom edge of the tube lens housing and the entrance pupil of the objective, can be set anywhere within the range specified in the table above, since the rays from the objective are in parallel bundles. If the tube lens is too close, the image may suffer from aberrations; if it is too far, vignetting will occur.
Lenses with external SM2 threads are engraved with an arrow next to an infinity symbol (∞) to indicate which side of the lens should face the objective (infinity space), as shown in the diagram above. Item #'s TTL200 and ITL200 should be inserted with the M38 x 0.5 threading facing the objective.
Tube Lenses for Laser Scanning and Widefield Imaging
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This schematic shows the TTL200MP Tube Lens in a laser scanning configuration with the working distance and pupil distance called out. The working distance corresponds to the distance from the edge of the housing below the engraving to the intermediate image plane. The pupil distance is defined as the distance between the edge of the tube lens housing above the engraving and the entrance pupil of the objective.
These lenses are engraved with an arrow next to an infinity symbol (∞) to indicate which side of the lens should face the objective (infinity space), as shown in the diagram above.
When viewing an image with a camera, the system magnification is the product of the objective and camera tube magnifications. When viewing an image with trinoculars, the system magnification is the product of the objective and eyepiece magnifications.
Magnification and Sample Area Calculations
The magnification of a system is the multiplicative product of the magnification of each optical element in the system. Optical elements that produce magnification include objectives, camera tubes, and trinocular eyepieces, as shown in the drawing to the right. It is important to note that the magnification quoted in these products' specifications is usually only valid when all optical elements are made by the same manufacturer. If this is not the case, then the magnification of the system can still be calculated, but an effective objective magnification should be calculated first, as described below.
To adapt the examples shown here to your own microscope, please use our Magnification and FOV Calculator, which is available for download by clicking on the red button above. Note the calculator is an Excel spreadsheet that uses macros. In order to use the calculator, macros must be enabled. To enable macros, click the "Enable Content" button in the yellow message bar upon opening the file.
Example 1: Camera Magnification
Example 2: Trinocular Magnification
Using an Objective with a Microscope from a Different Manufacturer
Magnification is not a fundamental value: it is a derived value, calculated by assuming a specific tube lens focal length. Each microscope manufacturer has adopted a different focal length for their tube lens, as shown by the table to the right. Hence, when combining optical elements from different manufacturers, it is necessary to calculate an effective magnification for the objective, which is then used to calculate the magnification of the system.
The effective magnification of an objective is given by Equation 1:
Here, the Design Magnification is the magnification printed on the objective, fTube Lens in Microscope is the focal length of the tube lens in the microscope you are using, and fDesign Tube Lens of Objective is the tube lens focal length that the objective manufacturer used to calculate the Design Magnification. These focal lengths are given by the table to the right.
Note that Leica, Mitutoyo, Nikon, and Thorlabs use the same tube lens focal length; if combining elements from any of these manufacturers, no conversion is needed. Once the effective objective magnification is calculated, the magnification of the system can be calculated as before.
Example 3: Trinocular Magnification (Different Manufacturers)
Following Equation 1 and the table to the right, we calculate the effective magnification of an Olympus objective in a Nikon microscope:
The effective magnification of the Olympus objective is 22.2X and the trinoculars have 10X eyepieces, so the image at the eyepieces has 22.2X × 10X = 222X magnification.
Sample Area When Imaged on a Camera
When imaging a sample with a camera, the dimensions of the sample area are determined by the dimensions of the camera sensor and the system magnification, as shown by Equation 2.
The camera sensor dimensions can be obtained from the manufacturer, while the system magnification is the multiplicative product of the objective magnification and the camera tube magnification (see Example 1). If needed, the objective magnification can be adjusted as shown in Example 3.
As the magnification increases, the resolution improves, but the field of view also decreases. The dependence of the field of view on magnification is shown in the schematic to the right.
Example 4: Sample Area
Sample Area Examples
The images of a mouse kidney below were all acquired using the same objective and the same camera. However, the camera tubes used were different. Read from left to right, they demonstrate that decreasing the camera tube magnification enlarges the field of view at the expense of the size of the details in the image.
Thorlabs offers eight infinity-corrected tube lenses for widefield imaging. All TTL series lenses can provide diffraction-limited performance about any single wavelength from 400 to 2000 nm, provided that the tube lens is set to focus on the camera at the target wavelength. Please note that using these lenses for laser scanning will result in vignetting and uneven spot sizes over the FOV; for integration into a telecentric laser scanning system, see the tube lenses below.
The lenses coated for the visible wavelength range (350 - 700 nm) offer good performance at shorter wavelengths (<480 nm) to accommodate applications using 405 nm and 443 nm illumination. The TTL200-B is AR coated for the NIR wavelength range (650 - 1050 nm), making it ideal for NIR fluorescence and NIR DIC imaging. The TTL200-S8 utilizes a broadband MgF2 single-layer coating with a low transmission roll-off throughout the visible and NIR, with peak transmission centered at 830 nm. See the graphs in the table below for transmission data. All TTL series lenses can be custom coated with either a single layer or a multi-layer AR coating optimized for transmission over a user-specified wavelength range; contact Tech Support for details.
With the exception of the TTL200 and the ITL200, all of these tube lenses are engraved with an arrow next to an infinity symbol (∞) to indicate which side of the lens should face the objective (infinity space). Item #'s TTL200 and ITL200 should be inserted with the M38 x 0.5 threading facing the objective.
The TTL200 and ITL200 use external M38 x 0.5 threading for direct compatibility with Nikon and Thorlabs microscopes. This threading can be converted to external SM2 (2.035"-40) threading using the SM2A20 adapter available below. Alternatively, the WFA4111 Dovetail Adapter, also available below, directly accepts a TTL200 or ITL200 tube lens and can integrate it with a Cerna microscope. We also offer the WFA4110 Dovetail Adapter, which is a version of the WFA4111 with the TTL200 tube lens built in.
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Our four tube lenses for laser scanning and widefield imaging are designed to have the same track length, defined as the distance between the image plane of the tube lens and the entrance pupil of the objective.
These infinity-corrected tube lenses feature a telecentric design appropriate for both laser scanning and widefield imaging applications. They are all designed with a nominal track length of 420 mm, allowing tube lenses of different focal lengths to be substituted into an existing system without realigning the imaging device or objective.
These laser scanning tube lenses can be paired with our SL50-CLS2 (450 - 1100 nm) scan lens to create a telecentric system. The extended range of the AR coating on the TTL200MP also makes it compatible with our SL50-2P2 (680 - 1600 nm) or SL50-3P (900 - 1900 nm) scan lenses. All of these lenses can be custom coated with either a single layer or a multi-layer AR coating optimized for transmission over a user-specified wavelength range between 400 nm and 2000 nm; contact Tech Support for details.
These tube lenses are engraved with an arrow next to an infinity symbol (∞) to indicate which side of the lens should face the objective (infinity space).
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A WFA4111 can be used to integrate a TTL200 tube lens into a custom epi-illumination module on a DIY Cerna Microscope.
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The WFA4111 adapter allows M38 x 0.5-threaded tube lenses to be easily integrated with Cerna microscopes and SM2-threaded components.
Thorlabs offers two styles of adapters for use with the externally M38 x 0.5-threaded TTL200 and ITL200 tube lenses, allowing them to be integrated with Thorlabs' SM2 lens tube systems and Cerna DIY Microscopy Platform. Our other tube lenses already have external SM2 (2.035"-40) threads.
Our WFA4111 Dovetail Adapter directly accepts the TTL200 and ITL200. Alternatively, external SM2 threads on the top of the adapter allow externally SM2-threaded lenses to be connected via an SM2M05 lens tube. The bottom of the adapter features a male D1N dovetail, making it compatible with our DIY Cerna systems. The SM2 threads on top can also be used to integrate user-designed camera tubes constructed from SM2-threaded lens tubes.
The SM2A20 allows the TTL200 and ITL200 to be easily converted to SM2 threading, enabling the construction of an optical system consisting of a scan lens and a tube lens using Thorlabs' standard SM2 lens tube components and the SM2-threaded GCM102(/M) 2D galvo mounting adapter. We also offer SM2-threaded adapters for common objective threads.
The SM38RR retaining ring can be used to lock the tube lens in place when using either adapter. We also offer the WFA4110 Dovetail Adapter, a version of the WFA4111 adapter that includes the TTL200 tube lens.