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Microscope Objective Turret, SM1-Compatible

  • Objective Lens Turret with 4 RMS-Threaded Mounting Ports
  • RMS-Threaded Objective and Turret Caps
  • SM1-Threaded Mounting Interface

OT1 Lens Turret


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OT1 Lens Turret

with 4 Microscope Objectives

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The OT1 is an SM1-compatible compact objective lens turret with four RMS-threaded ports. The housing is primarily constructed of aluminum but has steel inserts at critical points to ensure the durability and precision of the detent mechanism that reproducibly positions the objective lenses with a bi-directional repeatability of ±2.5 µm. The mounting interface for the OT1 objective lens turret has SM1 (1.035"-40) threading so that it can be easily integrated into custom imaging systems built using Thorlabs' Lens Tube and Cage Systems. To mount the OT1 in a cage system, use a CP02 or CP02T for a 30 mm cage system and an LCP02 for a 60 mm cage system. The OT1 is designed to securely hold objectives in either horizontal or vertical orientations.

The RMSCP1 and RMSCP1 are caps designed to protect unused lens turret ports, microscope objectives, and other RMS (0.800"-36) threaded components. The RMSCP2 features external RMS threading for the lens ports of the OT1, while the RMSCP1 features internal RMS threading for microscope objectives.

We also offer 5-Position Objective Holders that are compatible only with DIY Cerna® Microscope Systems.

Posted Comments:
useinov  (posted 2018-02-22 09:53:38.673)
How can I make sure that OT1 is compatible with Mitutoyo components VMU-V (Mitutoyo product code 378-505) and Mitutoyo objectives M APO 5x (378-802-6), 10x (378-803-3), 20x (378-804-3) and 50x (378-814-4)
bhallewell  (posted 2018-02-27 10:14:41.0)
Response from Ben at Thorlabs: The OT1 is compatible with RMS-Threaded (0.800"-36) Objective Lens Ports. We have a range of adapters in the following link however for larger threads, the adapter may foul with the OT1 body itself.
ryan.scott  (posted 2017-06-13 11:07:42.75)
This product would be very useful if it came in an female SM1 version so that it can be adapted for using long working distance objectives with M26 x 0.706 threads.
awebber-date  (posted 2017-06-14 11:42:09.0)
Response from Alex at Thorlabs: Thank you for the feedback. We are always looking for new product ideas so it is greatly appreciated. I will follow up with our engineers since there is clearly a demand for this product.
k.zesewitz  (posted 2017-05-24 12:40:32.137)
Could you please do a female SM1-version of that on the lens side, finally? I saw that you're in the "process of reviewing this" since 2015. Is there any result yet? I mean a SM1 threading would make much more sense than RMS cause its still compatible to RMS but allows SM1 too.
bwood  (posted 2017-05-25 10:08:21.0)
Response from Ben at Thorlabs: Thank you for leaving this feedback. Unfortunately, we do not have any immediate plans to release this, however we are constantly working to expand our product line. Customer recommendations are an important part of this process, and I will reiterate this requirement to our engineers.
ludoangot  (posted 2015-10-13 10:41:23.157)
It would be very useful if you could make a similar turret but with female SM1 threads (on the lens side) rather than RMS. The vast range of your SM1 adapters would allow mounting larger diameters microscope lenses (nikon, mitutoyo,...) in addition to any custom made assembly based on your sm1 tubes. I'm aware you offer RMS to other microscope mounts but RMS is smaller than nikon 25 and mitutoyo 26mm diameter mounts. (I see someone else also suggested this version)
besembeson  (posted 2015-10-14 04:45:27.0)
Response from Bweh at Thorlabs USA: Thanks for the feedback. We are in the process of reviewing this.  (posted 2015-10-08 19:48:49.4)
There is a lot of play in the turret, in that its rotation axis allows for some jiggling even after an objective has been clicked into place. I would estimate that the image (and thus the tip of the objective) can be translated side to side by +/- 0.5 mm based on the wiggle-room allowed by the turret rotation. Is there something I can do to tighten this up? We are operating in a manufacturing environment where there are lots of vibrations. The instability of the turret only adds to the image stability issues.
besembeson  (posted 2015-10-14 03:44:24.0)
Response from Bweh at Thorlabs USA: This issue has been addressed in the new design. The OT1 mounting tube is bolted now. I will follow-up to address this issue with your unit.
ludoangot  (posted 2015-10-01 12:18:27.77)
Poster rickl (2008-03-21) pointed out a design flaw in the turret. Has this been corrected in the currently manufactured turret or is the design still incorporating glued sleeves?
rcapehorn  (posted 2015-10-02 10:25:48.0)
Response from Rob at Thorlabs: Thank you for your interest in our OT1. I can confirm that this issue has been addressed and that the turret tube is now screwed and bonded in place.  (posted 2015-08-31 21:39:22.58)
We want to use one of these in conjunction with your LTFW6 light-tight filter wheel. Specifically, we would like to bolt the filter wheel to the top SM1 port of the OT1. I imagine a lens tube would be necessary between the OT1 and the LTFW6 to make the parts fit together? Seems like a simple adapter might not give enough clearance. What would you recommend?
besembeson  (posted 2015-09-29 01:12:33.0)
Response from Bweh at Thorlabs USA: You may want to consider using an SM1V10
cbrideau  (posted 2015-07-30 12:24:48.42)
Still waiting for an SM1 version of this part. Given the wide variety of SM1-to-whatever adapters you have this would allow great flexibility in mounting objectives. RMS is just too small for modern lenses.
jlow  (posted 2012-08-01 12:57:00.0)
A response from Jeremy at Thorlabs to Guy: Thank you for leaving your feedback online. I will contact you directly to discuss about this possibility.
gyg2101  (posted 2012-07-27 11:16:54.0)
Hi, Could you make a Nikon CFI-60 compatible version of OT1? Thanks guy
tcohen  (posted 2012-04-18 09:35:00.0)
Response from Tim at Thorlabs: The RMS threads of the OT1 will hold the objectives snugly, and a typical set up can include a horizontal setup.
gao53  (posted 2012-04-13 16:58:26.0)
If I mount OT1 horizontally with 4 microscope objectives on it, can it hold them firmly without becoming loose?
bdada  (posted 2011-10-10 17:24:00.0)
Response from Buki at Thorlabs: Thank you for your suggestion. We will pass it on to our design engineers for consideration as we continue expanding our selection of microscopy accessories.
user  (posted 2011-10-06 18:30:09.0)
Any chance you can make a linear version of this ? Like a filter slider with position detents used in many microscopes. The accuracy may increase.
jjurado  (posted 2011-08-02 16:18:00.0)
Response from Javier at Thorlabs to last poster: Thank you very much for your feedback. We apologize about the inconvenience with your objective lens turret. We really have not experienced significant quality issues with this product, so it is most likely an isolated case. However, we would like to discuss this in detail with you, so that we can ensure your satisfaction with the performance of this part. Please contact us at and we will gladly assist you.
user  (posted 2011-08-02 10:58:39.0)
I purchased one to mount inverted. However the repeatability of 2.5 um is not what I observe. The turret is simply too loose and by lightly tapping on the side of a mounted objective the image will move and not return to the previous position. I tried to tighten the spring-loaded screw but it was only stable when it was so tight, that it couldnt be moved at all. It feels miles away from quality turrets from either Zeiss, Olympus, Nikon, which are much more solid in construction. I am hoping that it was a manufacturing error and that my next one will be of better quality.
Tyler  (posted 2008-03-21 16:23:22.0)
Response from Tyler at Thorlabs to Rick: Thank you for informing us of this engineering failure. We are happy to hear that your optics we not damaged when the part failed. I have arranged for a second OT1 to be sent to you for free and you should receive it on Monday morning. We will also review the construction of the OT1 in order to eliminate this design flaw. Thank you again for the feedback, we always appreciate it when our customers participate in making our products better.
rickl  (posted 2008-03-21 15:26:39.0)
I purchased one of these turrets. I liked the simple design and compact 4 positions. UNFORTUNATELY there is a BIG manufacturing flaw. The threaded sleeve that is attached to the angled suface which holds the objectives is actually GLUED on, not threaded or bolted. The picture on the catalog page for this item shows some fairly nice objectives which could easily cost thousands of dollars. Im sure the owner of those objectives wouldnt be too happy to see his objectives crash to the ground because the glue didnt hold his turret together. Luckily, I only had the turret mounted (no optics) when mine broke. Ive since had my machinist bolt these two parts together, something Id recommend be implemented in your manufacturers process. I do need another one of these items, Id like to get a good discount on the next one if possible, since it requires about $100 of additional machining cost to mount the sleeve properly. Please let me know if this is possible. thank you, Rick Logemann BioImaging Solutions 858-356-0669 PH

Microscope Objective Lens Turret, SM1-Compatible 

  • 4 RMS-Threaded (0.800"-36) Objective Lens Ports
  • SM1-Threaded (1.035"-40) Mounting Interface
  • Precision Detent Mechanism for Objective Lens Positioning
Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
OT1 Support Documentation
OT1Objective Lens Turret, 4 RMS-Threaded Objective Ports

RMS-Threaded Caps

Objective Lens Turret Protected by RMSCP2 Dust Cap
Click to Enlarge

RMSCP2 Protecting Turret Ports of an Inverted Microscope
Microscope Objective Covered by RMSCP1 Dust Cap
Click to Enlarge

RMSCP1 Covering an Objective
  • RMSCP1: Internally RMS-Threaded Cap for Microscope Objectives
  • RMSCP2: Externally RMS-Threaded Cap for Objective Lens Turret Ports

These RMS-Threaded Caps are designed to protect microscope objectives, objective lens turret ports, and other RMS (0.800"-36) threaded components. The RMSCP1 has internal RMS threading, making them compatible with standard RMS-threaded microscope objective lenses. The RMSCP2 has external RMS threading to cover unused objective lens ports (see image on the far right). Each of these caps is made from anodized aluminum and has a knurled edge for secure hand tightening.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
RMSCP2 Support Documentation
RMSCP2Externally RMS-Threaded Cap for Objective Lens Ports
RMSCP1 Support Documentation
RMSCP1Internally RMS-Threaded Cap for Microscope Objective Lenses
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