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Infinity-Corrected Tube Lens

  • Designed for Use with Plan Fluorite Objectives
  • Easily Incorporated into Complex Optical Systems

Application Idea

ITL200 Lens in an SM2A20 Adapter 



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  • True Imaging Lens for Forming a Well-Corrected Infinity Optical System
  • Apochromatically Corrected for Lateral and Axial Chromatic Aberration Across the Field of View
  • Better Overall Aberration Correction than a Standard Achromat

The ITL200 is an infinity-corrected tube lens designed for use with our line of Nikon Plan Fluorite DryOil Immersion, and Physiology objectives. The tube lens has an effective focal length of 200 mm and is ideal for applications such as imaging onto a CCD camera. The lens features an apochromatic design consisting of two doublet lenses to correct lateral and axial chromatic aberration across the entire field of view in the visible range. The lens will have better overall aberration correction than a standard achromat, especially off axis. The lens also has diffraction-limited performance to field number 25 for visible wavelengths. The lens is AR coated to improve performance for visible wavelengths; please see the Specs tab for a plot of the transmission. For those interested in building their own tube lens with a focal length of 180 mm, we also carry Ø2" AR-coated achromatic doublets, specifically AC508-180-A and AC508-180-A-ML.

An objective lens creates an image of an object at infinity; put another way, the objective forms parallel bundles of light rays for each position on the object.The tube lens is designed to refocus these parallel bundles onto the active area of a detector, as illustrated in the diagram to the right. In the diagram, the blue rays originate from the object on the optical axis, while the red rays originate off-axis. Since the rays from the objective are in parallel bundles, the tube lens can be located anywhere from 70 to 170 mm from the shoulder of the objective for best results. If the tube lens is closer than 70 mm, the image may suffer from aberrations, and if it is farther than 170 mm, the tube lens will be overfilled.

The ITL200 tube lens can also be paired with the CLS-SL Visible Scan Lens. In this configuration, the tube lens will relay the scan plane of a laser scanning imaging system to the back aperture of the imaging objective.

Mounting Options
The M38 x 0.5 external thread on the ITL200 can be easily converted to SM2 (2.035"-40) threading using the SM2A20 adapter, which enables the construction of an optical system consisting of a scan lens and a tube lens using Thorlabs' standard SM2 lens tube components. We also offer SM2-threaded adapters for common objective threads. 

Alternatively, Thorlabs' WFA4110 Dovetail Adapter features a built-in ITL200 tube lens with a male D1N dovetail, making it compatible with our DIY Cerna systems. The WFA4110's external SM2 threads also make it compatible with SM2-threaded lens tubes.

Typical Application and Spacing of ITL200 Tube Lens
Tube Lens Schematic
Click To Enlarge

*For Best Performance
Effective Focal Length 200 mm
Working Distancea 148 mm
Optimal Distance Between Tube Lens and Objective 70 - 170 mm
Lens Design Apochromatic
AR Coating Visible Wavelengths
  • Measured from the housing edge to the image plane (see the diagram to the right).
Tube Lens Transmission
Click To Enlarge

To view an excel file that lists all of the measured transmission values for this tube filter, please click here.

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Posted Comments:
Posted Date:2016-06-06 14:15:41.05
Dear ladies and gentleman, may question is, why is the Working Distance much less than the focal lenght? Best regards Andreas
Posted Date:2016-06-08 09:23:25.0
Response from Bweh at Thorlabs USA: The focal length is relative to a principal plane of the actual lens element which is inside the housing while the working distance is relative to the external housing edge.
Posted Date:2016-03-17 14:00:38.693
I also need the ITL200 front focal length, has Nikon provided this information? If not, would it be possible you measure it? Ideally a tick lens model of the ITL200 would be much welcome.
Posted Date:2016-03-17 02:59:42.0
Response from Bweh at Thorlabs USA: Unfortunately Nikon doesn't provide this information.
Posted Date:2016-03-11 03:32:34.817
Hi, if i have a lens attached to the camera sensor, should I keep a 148mm from the end of the ITL200 to the front mount of the lens attached to the camera?
Posted Date:2016-03-11 11:20:51.0
Response from Bweh at Thorlabs USA: The ITL200 is your imaging lens so the 148mm should be to the camera sensor. If you have an additional relay lens (which is not typical), then that distance should correspond to the object plane of your relay lens.
Posted Date:2016-02-19 09:33:28.01
Hello, my purpose is photography. My setup: - Olympus OMd-Em5II camera; - Mitutoyo Mplan 5 and 10x lens. Between the lens and the camera I've an iris diaphragm (from thorlabs) and a raynox dcr250 as tube lens. Between the raynox and the camera I've a extension bellows at 100mm. Well, I'm not happy with the setup and I would like to try the ITL200 instead of the raynox. I need some advices about the distances between the mitutoyo and the ITL200 and the ITL and the camera sensor? Many thanks in advance. Sincerely, Pedro Alves
Posted Date:2016-03-03 04:05:05.0
Response from Bweh at Thorlabs USA: The camera sensor should be about 148mm from the end of the ITL200 and the front of the ITL200 can be between 70-170mm from the end of the objective.
Posted Date:2016-03-03 04:05:05.0
Response from Bweh at Thorlabs USA: The camera sensor should be about 148mm from the end of the ITL200 and the front of the ITL200 can be between 70-170mm from the end of the objective.
Posted Date:2015-11-19 19:55:17.567
I want to know where are the principal planes of the ITL200.
Posted Date:2015-11-20 02:30:45.0
Response from Bweh at Thorlabs USA: The back focal length is 148mm. We don't have information on the front focal length. I will contact you if Nikon can provide this.
Posted Date:2015-10-27 14:30:16.873
Can this tube lens used with a Leica Infinity-corrected objective? Thanks!
Posted Date:2015-11-05 10:19:41.0
Response from Shawn at Thorlabs China: It depends on your application. If it involves a monochromatic source, then it should be okay but it may not be very suitable if you have to account for chromatic aberration. This is because Leica (and Zeiss) microscopes have color correction inside their tube lens. They don't correct for chromatic aberrations in the objective. Nikon (and Olympus) have color correction in the their microscope objectives, not in the tube lens.
Posted Date:2015-04-14 08:59:22.95
dear All, I need a thecnical contact to explane my castom problem. Andrea
Posted Date:2015-04-15 04:03:15.0
Response from Jeremy at Thorlabs: You can contact us at to discuss about your application.
Posted Date:2015-01-29 19:02:32.153
The focal length is 148mm from the mounting side, what is it from the other side?
Posted Date:2015-01-29 02:13:12.0
Response from Jeremy at Thorlabs: The orientation, distances, and dimension of the tube lens are located in the drawing under "Specs" tab. I am not sure I fully understand your question. Since you did not leave any contact information, can you contact us at to discuss about this further please?
Posted Date:2015-01-05 11:30:45.733
Could you please specify the focal length tolerance on this lens system?
Posted Date:2015-01-09 01:37:27.0
Response from Chris at Thorlabs: The specified tolerance is +/-1%, but it is realistic to expect it to be closer to +/-0.5%.
Posted Date:2014-07-29 19:00:57.11
You should offer a 2 inch lens tube with internal SM2 threads on one end and set screws for attaching a C-mount on the other end. The lens tube should be the appropriate length, such that when used with the ITL200 lens and the SM2A20 adapter, the sensor of a camera mounted at the C-mount would be the correct focal distance away from the ITL200 lens.
Posted Date:2014-08-07 02:53:02.0
Response from Chris at Thorlabs: Thank you for your suggestion. We will discuss the idea internally and it may be something you see offered as a standard product in the future. We welcome any product ideas which you think would serve to help make our products more useful in your applications.
Posted Date:2014-06-25 19:07:09.623
Hi, I purchased this ITL200 lens and it seems to me that the front focal length is more like 250mm by trying to image an obect located at > 10x the measured focal lens (assumed to be infinity). I need to know where is the front focal plane for my experiment and since no zemax file is given it's hard to be convinced. Is this lens being tested by Thorlabs? Has anyone else seen this? Thanks,
Posted Date:2014-07-21 02:29:59.0
Response from Jeremy at Thorlabs: The effective focal length of the lens is 200mm and its back focal length is 148mm from the mounting side (smaller aperture side). It will probably be better to measure this with sun light instead.
Posted Date:2014-05-21 10:21:08.717
Posted Date:2014-05-22 09:45:20.0
A response from Bweh Esembeson at Thorlabs USA: Thanks for contacting Thorlabs. Unfortunately we don’t have the Zemax file for this tube lens at this time. If your objective is infinity corrected, then you can calculate the magnification with the tube lens from the ratio of the focal length of the tube lens and that of the objective. The distance between the tube lens and objective can be adjusted (70mm - 170mm for the ITL200) so that all the off-axis rays from object can be brought to the image plane. I will contact you through our China office to know the properties of your objective and help determine the magnification.
Posted Date:2014-05-15 14:13:54.85
SM2AD36 is exactly what I was looking for! Strangely, this component is not listed in the table of adapters, therefore, I could not find it. But thanks for the hint! Pearu
Posted Date:2014-05-15 02:38:28.0
Response from Bweh E at Thorlabs. Thanks for the feedback. The adapter selection guide is a new feature and we are continuously improving this. Based on your comment, we will look into creating more linkage between these products.
Posted Date:2014-05-15 12:23:39.65
Hi, I have 36mm diameter lens (original Nikon back port tube lens) and I wonder if you could provide a tube or any system where to attach such a lens? ITL200 seems to be about the same size (might be too small). Could it fit a 36mm diameter lens? Best regards, Pearu
Posted Date:2014-05-15 11:12:18.0
A Response from Bweh E at Thorlabs in Newton: Thanks for contacting Thorlabs. The ITL200 has an M38x0.5 threaded port which can accommodate the 36mm diameter lens but I am not sure how the thickness of your lens compares with the available space on the ITL200 housing. Besides, we don’t have M38x0.5 retaining rings at this time. We will look into having these as a stock item subsequently. One combination that could possible work for you depending on the thickness of your lens will be the SM2AD36 ( in conjunction with the SM2A20 (
Posted Date:2013-09-09 11:46:57.343
Is this tube lens ITL200 compatible with the Olympus Plan Fluorite objectives? Or, do you have a better solution for these lenses? Thanks
Posted Date:2013-09-12 14:15:00.0
Response from Chris at Thorlabs: Thank you for using our feedback tool. The Olympus objectives are typically intended to be used with a tube lens with a focal length of 180mm. There's not really any particular reason that one cannot be used with a different focal length such as the 200mm ITL200, but it should be noted that the magnification will increase by a factor of 200/180 (10/9).
Posted Date:2013-02-18 12:15:19.857
I need the prescription of the ITL200 tube lens to incorporate it into our system. A .zmx file, please.
Posted Date:2013-02-20 20:23:00.0
Response from Chris at Thorlabs: Thank you for using our web feedback. We will contact you directly about the ITL200.
Posted Date:2012-10-18 12:05:00.0
Response from Tim at Thorlabs to Reto: This is a Nikon tube lens offered for users to be able to design complete microscope systems from our standard components.
Posted Date:2012-10-15 12:35:45.687
To whom it may concern: Is the ITL200 a tubelens manufactured by Nikkon or is it a Thorlabs design? Best, Reto
Posted Date:2012-09-13 10:25:00.0
Response from Jeremy at Thorlabs: The entrance aperture is about 30mm and the exit aperture is about 23.9mm.
Posted Date:2012-09-06 13:31:06.0
What is the aperature size of the ITL200 tube lens?
Posted Date:2012-08-15 15:47:00.0
Response from Jeremy at Thorlabs: The distance between the objective shoulder and the housing of the tube lens should be around 70mm to 170mm for best performance. This distance is also called out in the diagram under the Overview tab.
Posted Date:2012-08-14 19:31:26.0
What is the optimal distance between ITL200 and a Nikon CFI60 objective?
Posted Date:2012-07-26 16:15:00.0
A response from Tor at Thorlabs: Thank you for taking the time to contact us. The tube lens is designed for compatibility with the Nikon CFI60 objectives. The performance will be very similar to that of the tube lenses provided with these microscopes. These are apochromatically designed, so they will offer better color-correction as compared to a standard achromatic lens. This is AR-coated for the visible spectrum; we are in the process of measuring the transmittance over the next few weeks, and I will share these data with you as soon as they are available. Please contact if you have additional inquiries.
Posted Date:2012-07-24 11:47:58.0
I have the same question (and some more): is the ITL200 similar to the tube lenses found in Olympus or Nikon microscopes? Is it anti-reflection coated? Could you specify the advantages over using achromatic lenses? What is the transmittance? Thanks!
Posted Date:2012-04-18 09:33:00.0
Response from Tim at Thorlabs: Thank you for your feedback. We are looking into this and will update you shortly.
Posted Date:2012-04-13 12:34:44.0
Is this tube lens compatible with any of the Nikon CFI60 series objectives? Is it the same tube lens found inside the body of the newest Nikon fluorescence microscopes (e.g. TE2000 or Eclipse Ti)?
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available / Ships
ITL200 Support Documentation
ITL200Infinity-Corrected Tube Lens for Plan Fluorite Objectives
SM2A20 Support Documentation
SM2A20Adapter with External SM2 Threads and Internal M38 x 0.5 Threads
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