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Periscope Assembly

  • Height Adjustment with ±4° Pitch, Yaw, and 360° Rotation
  • Periscope Components Also Offered

Pitch, Yaw, and Rotation
Top Unit Sold as RS99T


Complete Assembly
(Mirrors Not Included)

Rotating Bottom
Unit Sold as



Adjust Beam
Height and
(Mirrors Sold

Related Items

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This animation shows how the periscope assembly is used.


  • Periscope Assembly Designed for Use with Ø1" (Ø25.4 mm) Optics (Sold Separately)
  • Minimum Optic Thickness: 0.13" (3.3 mm)
  • Complete Periscope Assembly Redirects and Changes the Height of a Beam Within an Optical System
  • Fabricated from Black Anodized Aluminum
  • Optic Fixtures Available Separately for Wider Range of Height Adjustment

Thorlabs' Periscope Assembly provides a convenient way to redirect and change the elevation of a beam within an optical system. As seen in the animation, the system consists of a pair of 45° Ø1" mirror mounts (optics sold separately) with lockable adjustment knobs to provide 360° of rotation of the incoming light.

The top unit, which can be purchased separately below, provides pitch, yaw, and rotation control. It features 360° of continuous rotation as well as ±4° tip and tilt with an adjustment per revolution of 8 mrad/rev. This unit can hold Ø1" optics that are at least 0.13" (3.3 mm) thick.

The bottom unit, which can also be purchased separately below, provides a right angle mirror mount for Ø1" optics as well as a clear aperture for beam sampling. This unit is mounted to the Ø1" post using a 360° continuous rotation pillar post clamp.

RS99 SmartPack Packaging
Click to Enlarge

RS99 Packaging

Smart Pack

Item # % Weight
RS99 15.97% 7.50 kg
RS99/M 15.97% 11.56 kg

Smart Pack

  • Reduce Weight of Packaging Materials
  • Increase Usage of Recyclable Packing Materials
  • Improve Packing Integrity
  • Decrease Shipping Costs

Thorlabs' Smart Pack Initiative is aimed at waste minimization while still maintaining adequate protection for our products. By eliminating any unnecessary packaging, implementing packaging design changes, and utilizing eco-friendly packaging materials for our customers when possible, this initiative seeks to improve the environmental impact of our product packaging. Products listed above are now shipped in re-engineered packaging that minimizes the weight and the use of non-recyclable materials.b As we move through our product line, we will indicate re-engineered packages with our Smart Pack logo.

  • Travel-based emissions reduction calculations are estimated based on the total weight reduction of packaging materials used for all of 2013’s product sales, traveling 1,000 miles on an airplane, to provide general understanding of the impact of packaging material reduction. Calculations were made using the EPA’s shipping emissions values for different modes of transport.
  • Some Smart Pack products may show a negative weight reduction percentage as the substitution of greener packaging materials, such as the Greenwrap, at times slightly increases the weight of the product packaging.

Posted Comments:
gayatripc  (posted 2018-10-23 23:38:12.083)
Using the periscope, we need to direct the incoming laser beam to a specific height and parallel to the table so that is passes through a series of lenses for collimation. For that, the position of both the top unit and bottom unit need to be adjusted systematically. When we loosen the screw, it becomes very loose and we need a steady hand to adjust the beam direction. Then when we tighten the screw, that position changes, depending on how we hold the unit. This is very difficult to work with. Do you have any periscopes that are easier to handle? Or a clamp that can go below each unit so that it doesn't slide down?
llamb  (posted 2018-10-24 09:43:38.0)
Thank you for your feedback. While we do not have other periscopes in our catalog, I have added these ideas to our internal product forum for further development. To make the current RS99(/M) periscopes stabler, you can consider using our Ø1" Post C-Clamps like our RM1A or RM1B to prevent the loosened units from sliding down.
hamburge  (posted 2017-03-15 11:15:53.72)
Dear, i am interested in such a product. I would need a version for 2" optics. As i have seen the comment below, can you provide such holders for 2 inch optics?
tfrisch  (posted 2017-03-15 08:21:56.0)
Hello, thank you for contacting Thorlabs. I will reach out to you about parts that may be used to make a similar periscope for 2" mirrors.
yweix9  (posted 2016-10-03 18:06:48.947)
I am looking for a periscope similar to RS99, shown in the picture. But the diameter of our mirrors are 2 inches. I am wondering if you have periscope for 2 inch mirrors?
jlow  (posted 2016-10-05 01:57:29.0)
Response from Jeremy at Thorlabs: We do not currently have a version for 2 inch optic but one can construct a similar setup using our components. I will contact you directly to discuss about this.
sanchari.biswas  (posted 2015-05-25 12:12:16.493)
I need to change the height of the beam by either 4mm or 34mm. Is it possible to use this product. Any suggestion ?
besembeson  (posted 2015-08-20 04:18:27.0)
Response from Bweh at Thorlabs USA: You can get the 34mm separation but the 4mm will not be possible. You may consider one of our retroreflectors for such 4mm separation. Check these at the following link:
jmbrown  (posted 2015-05-21 01:42:15.5)
Would it be possible to attach one of your motor actuators onto this device to precisely control the rotation of either the top or bottom unit with a computer?
besembeson  (posted 2015-08-24 09:18:27.0)
Response from Bweh at Thorlabs: This is not possible according to the design we currently have. Any actuator would interfere with the rotation knob.
aklossek  (posted 2014-06-10 08:07:56.44)
Dear ladies and gentlemen, I´ve read a lot about periscopes that rotate the polarisation. Is this the cas here. If yes how can I prevent this? Best regards André Klossek
besembeson  (posted 2014-06-12 09:25:52.0)
Response from Bweh at Thorlabs Newton-USA: Thanks for contacting Thorlabs. The RS99 will rotate the polarization of the light in the case when the output beam is out of plane with respect to the input beam (for example horizontal polarization state will become vertical and vice versa). If the incoming and outgoing beams from the RS99 are in the same plane, the polarization state will remain the same (with the oscillation axis of the vertical state rotated by 180 deg in principle). To compensate for case when the input and output beams in different planes, you can add a half waveplate ( or a Fresnel Rhomb retarder, FR600HM ( at the output of the RS99. I will contact you by email to further discuss your application.
bdada  (posted 2012-02-15 19:51:00.0)
Response from Buki at Thorlabs to mstocker: Thank you for your feedback. The RS99 includes a 6" (150mm) pillar post, so the height change of the beam would be less than 150mm because the mounted mirrors will not be placed at the very edge of the post. The post, RS6, is stackable, so you can connect two of them with a 1/4"-20 set screw, or with the AE8E25E screw adapter that ships with each pillar post. Please use the link below to get more information about the pillar post. We have a variety of lengths that will help you achieve the height change you want for your beam. Please contact if you have any questions.
mstocker  (posted 2012-02-08 13:24:56.0)
I need to reflect a beam 90 degrees (parallel to the laser table) and change the height by ~ 1.5 cm. With the 45 degree mounts for RS99, will it be possible to do this? If not, is there another option?
Laurie  (posted 2008-10-13 09:07:02.0)
Response from Laurie at Thorlabs to xdcui: Thank you for your feedback. The imperial version (RS99) has an 8-32 thread and the metric version (RS99/M) has an M4 thread. We offer a screw adapter from either of these standards to the M6 standard. To go from M4 to M6, I suggest item# AP6M4M, and to go grom 8-32 to M6, we have AP6M8E.
xdcui  (posted 2008-10-10 02:10:39.0)
I notice that the mounting hole on the top of the rod is M4 (RS99). While all your 1" extension rods have the mounting tap of M6. How to make them connected?

Complete Periscope Assembly

  • Redirects and Changes the Height of a Beam Within an Optical System
  • Designed for Use with Ø1" (Ø25.4 mm) Optics (Not Included)
  • 360° Continuous Rotation with ±4° Tip and Tilt
  • Minimum and Maximum Beam Heights:
    • RS99: 1.8" and 4.6"
    • RS99/M: 46 mm and 114 mm
  • Includes 6" (150 mm) Tall RS6 (RS150/M) Post and CF175 Clamping Fork

The RS99(/M) Periscope Assembly includes the top and bottom units, Ø1" post, and clamping fork. The top unit provides pitch/yaw adjustment, which can be used to compensate for angular deviations of the input beam relative to the Ø1" (Ø25.4 mm) optic (not included). When used with standard 6 mm thick mirrors (not included), the center points of the mirrors can be positioned with a separation between them of 1.0" and 2.7" (RS99) or 25.4 mm and 65.5 mm (RS99/M). The included 6" tall post [RS6 (RS150/M)] can be extended using Ø1" Pillar Post Extensions and the included thread adapter.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
RS99 Support Documentation
RS99Complete Periscope Assembly, Imperial (Mirrors Not Included)
+1 Qty Docs Part Number - Metric Price Available
RS99/M Support Documentation
RS99/MComplete Periscope Assembly, Metric (Mirrors Not Included)

Top Unit of Periscope Assembly

  • Designed for use with Ø1" (Ø25.4 mm) Optics
  • 360° Continuous Rotation with ±4° Tip and Tilt
  • Includes Kinematic Post Clamp

The RS99T(/M) Top Unit is offered for customers who want to create their own periscope assembly on an arbitrary length Ø1" Pillar Post or post assembly. This assembly includes the kinematic post clamp with ±4º tip and tilt in addition to 360° continuous manual adjustment. The bottom unit, post, base, and clamping fork packaged with the RS99 periscope assembly featured above are not included with the RS99T.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
RS99T Support Documentation
RS99TTip/Tilt Rotation Beam Steering Assembly, Imperial
+1 Qty Docs Part Number - Metric Price Available
RS99T/M Support Documentation
RS99T/MTip/Tilt Rotation Beam Steering Assembly, Metric

Bottom Unit of Periscope Assembly

  • Designed for use with Ø1" (Ø25.4 mm) Optics
  • 360° Continuous Rotation
  • Clear Aperture for Beam Sampling

The RS99B(/M) Bottom Unit is a right angled mirror mount for use in a periscope assembly on an arbitrary length Ø1" Pillar Post or post assembly. This unit clamps to the post and offers 360° of continuous rotation without tip/tilt adjustment. The top unit, post, base, and clamping fork packaged with the RS99 periscope assembly featured above are not included with the RS99B.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
RS99B Support Documentation
RS99BRotating Beam Steering Assembly, Imperial
Lead Time
+1 Qty Docs Part Number - Metric Price Available
RS99B/M Support Documentation
RS99B/MRotating Beam Steering Assembly, Metric
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