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Pack of 5 Ø1/2" Posts
Pack of 5 Ø1/2" Post Holders
Pack of 5
Pack of 4 Cage Assembly Rods
Pack of 5 Mounting Bases
Pack of 5 Clamping Forks
Pack of 5 Lens Tubes
Thorlabs offers a variety of multipacks of different optomechanical parts for ordering convenience. Many of our most popular parts, including Ø1/2" posts, Ø1/2" post holders, and angle clamps, are available in packs of five. Packs minimize packaging waste, making orders more sustainable and reducing unpacking time. To jump to information about specific packs, please click on any of the images in the Quick Links table below.
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Washers: Using Them with Optomech
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Figure 2: Install washers before inserting bolts into slots to protect the slot from damage. The rounded, smooth side of the washer should be placed against the slot, and the rough, flat side should be in contact with the bolt head. The smooth surface is designed to translate easily across the anodized surface, without harming it. The BA2 base is illustrated.
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Figure 1: The diameter of the washer is 35% larger than that of the bolt head. This results in over a six fold increase in overlap area with the slot of a BA2 base. By distributing the force of the bolt over a larger area, the washer help prevent gouging of the slot.
The head of a standard cap screw is not much larger than the major diameter of the thread (Figure 1). For example, a 1/4"-20 screw has a head diameter between 0.365" and 0.375" and the clearance hole diameter for the threads is 0.264".
When the screw is tightened directly through the clearance hole to secure the device, the force is applied to the edge of the through hole, often cutting into the material (Figure 1).
Once the material is permanently deformed, the screw head will want to fall back into the gouged groove, thereby moving the device back to that location when attempting to make fine adjustments.
A device with a circular through hole is not meant to translate around the screw thread so the deformation is not expected to be a problem.
However, a slot should provide the ability to secure the device anywhere along the length for the lifetime of the part. Using a washer distributes the force away from the slot edge to decrease the chance of deforming the slot and extending the lifetime of the part. Figure 1 illustrates the difference a washer can make. The contact area between the slot of a BA2 base and a 0.27" diameter cap screw is 0.010 in2. When a 0.5" diameter washer is used the contact area is 0.064 in2, which is over six times larger.
When using a Thorlabs washer, there are two distinct sides (Figure 2). One side is flat and rough and the other is curved and polished. The curved and polished side should be placed against the device, which has an anodized surface.
As the screw tightens, the screw head can force the washer to spin against the anodized coating.
If the flat side is pressed down against the anodization, the friction created by the rough flat side can scratch the anodized aluminum. However, if the curved side is facing down, the smooth surface has less friction leading to less scratches and extending the visual appearance of the device.
Date of Last Edit: Dec. 4, 2019
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Each Post Features a
Ø1/8" (Ø3.2 mm) Hole
for Extra Leverage
Thorlabs’ Ø1/2" and Ø12.7 mm Optical Posts are a basic building block required in most rigid constructions. For convenience, Ø1/2" and Ø12.7 mm posts of varying lengths are available here in packs of 5. These precision-ground stainless steel posts are fabricated from 303 stainless steel and are compatible with our Ø1/2" post holders, which are also available in packs of 5.
Thorlabs also offers a line of Ø12.0 mm posts which are compatible with standard Japanese post holders and optomechanical components. Like the metric versions, these posts also feature an M4-threaded hole with removable setscrew on top and an M6-threaded tapped hole on the bottom, as well as an Ø1/8" (Ø3.2 mm) hole for tightening. In addition, these posts are compatible with our line of Ø1/2" post holders.
For other post options, or to order individual posts, please visit our Ø1/2" optical posts page.
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Each Post Holder Includes a Spring-Loaded Thumbscrew that Holds Posts in Place Before Tightening
These Standard Post Holders are designed with wide, square relief cuts that provide two lines of contact for highly stable post mounting. For convenience in ordering, post holders are available here in packs of 5. A spring-loaded plunger within each aluminum thumbscrew holds a steel post firmly within the post holder prior to final tightening. This design allows one-handed positioning of post-mounted devices. Thorlabs' imperial and metric post holders are equipped with our 3/16" (TS25H) and 5 mm (TS6H/M) spring-loaded hex-locking thumbscrews, respectively. The post holders are compatible with our entire line of Ø1/2" optical posts and mounting bases, which are both also available in packs of 5.
To order individual post holders, or for more options, including other post holder lengths, please see our Ø1/2" post holders page.
Our 360° swivel base adapter fits standard Ø1/2" post holders (sold above) with 1/4"-20 (M6) mounting holes and minimizes the amount of time it takes to assemble an optical system. In addition, the swivel design is ideal for applications that require a large number of components to be packed into a small area. When our Ø1/2" post holders are used with this adapter, the combination is nearly that of our very popular Universal Post Holders (common sizes also available below). This anodized aluminum adapter has the benefit of compatibility with any of our existing Ø1/2" post holders but does not offer the same height flexibility of the swiveling post holders, which allow the post to be lowered all the way to the table.
To order individual swivel base adapters, please visit our Ø1/2" post holders page.
Our line of Universal Post Holders offers several convenient features that make it easy to construct a new assembly. The swiveling base allows you to place your optic mount at the desired location and then simply swivel the base until it lines up with a convenient mounting hole on the optical table. Additionally, the post holder base is equipped with magnets that provide holding force for rough optic alignment prior to final lockdown. For additional height adjustment, the hollow base allows a Ø1/2" Post to rest upon the optical table, allowing the largest range of height adjustment of the post. These post holders are equipped with a TS25H(/M) 3/16" (5 mm) drive spring-loaded hex locking thumbscrew.
To order individual post holders, or for more options, including other post holder lengths, please see our Ø1/2" universal post holders page. To order these post holders without magnets, please contact Tech Support.
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A vertical setscrew allows for fine adjustment of the post height.
The R2(/M) Slip-On Collar locks onto a Ø1/2" post with a thumbscrew. By positioning the collar on a post so that it rests on the top of the post holder, the post can be rotated without altering the height of the mounted component. In addition, the R2 is equipped with a 4-40 setscrew. By using a 0.050" (1.3 mm) hex key, this adjustment screw allows for approximately 0.25" (6.4 mm) of post height adjustment (see photo to the right) without the need for a translating post or post holder. To restrict the rotation of the post, the R2 can be paired with the TRK05 anti-rotation adapter.
To order individual post collars, see our alignment stops page.
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Turning the 8-32 brass-tipped screw locks the RT2 collar onto a post.
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The R2T collar marks the vertical position of a post inside a post holder.
The R2T is a thinner version of the R2 Post Collar featured above and can be secured to a Ø1/2" post by turning the included 8-32 brass-tipped locking screw. By placing the collar on a post so that it rests on the top of the post holder, the post can be rotated or removed and replaced without altering the height of the mounted component. At a thickness of only 0.23", the R2T collar occupies minimal space on the post and allows any mounted component to be positioned vertically close to the post holder.
To restrict the rotation of the post, the R2T can be paired with the TRK05 anti-rotation adapter. Alternatively, each R2T has a small groove, shown in the photo to the left, that allows it to be used as an extra post collar in setups using the RMC Position-Maintaining Post Collar (available below).
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TR4M Post Spacer Underneath a TR3 Post with a KM100 Mirror Mount.
The 1/4"-20 setscrew is threaded directly into the optical table.
These stainless steel post spacers, also known as shims, are designed for achieving intermediate heights of our TR series Ø1/2" posts without compromising structural rigidity. They have a diameter of 0.50" (12.7 mm) to fit underneath the Ø1/2" posts sold above. The center clearance hole allows 1/4"-20 (M6) setscrews to pass through to the mating tap of the components on either side of the spacer.
By adding a Ø1/2" post spacer to a TR series post, it is easy to adjust the height of the center of optical components. An optic mounted in our LMR1(/M) or FMP1(/M) mount has its center at a height of 0.87" (22.1 mm) above the top of the post. Placing a TR3M post spacer under the post brings the optical axis height to 0.99" (25.1 mm).
Setscrews are not included with these post spacers. 1/4"-20 and M6 setscrews are available here.
Thorlabs' Angle Clamps securely fasten our Ø1/2" posts at a variety of angles. In addition to fixed 45° and 90° options, we also offer the SWC-P5, a variant for 360° continuous adjustment. All of our angle clamps are available here in packs of 5 for ease of ordering.
The holes of these clamps are double-bored to provide two lines of stable contact. The RA180(/M)-P5 clamps have one double-bored hole and a 1/4"-20 (M6) threaded stud on the bottom of each clamp, which allows them to be directly threaded onto a post. The 3/16" (5 mm) hex thumbscrews located at either side of the clamps secure the Ø1/2" posts in place once the desired position is achieved.
For more angle options, or to order individual angle clamps, please see our Ø1/2" construction accessories page.
These stackable Ø1" lens tubes provide a fast and easy means for building compact optical assemblies. Their stackable design and direct interfacing with any SM1-threaded (1.035"-40) components provide flexibility for complex optomechanical assemblies. Each 5-pack includes one retaining ring per lens tube for a total of five rings.
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The C128CC can be mounted onto any 30 mm cage-compatible component with 4-40 cage rod mounting holes.
The C128CC lens tube clamp is designed to enable easy placement and removal of aluminum lens tube covers in optical systems. The clamp is a two-piece design that utilizes two captive 5/64" (2.0 mm) cap screws to connect the two pieces. A 5/64" (2.0 mm) locking setscrew is included to provide the mounting force needed to secure the component in place. Two #4 counterbores, spaced 30 mm apart, on the front of the clamp are included to attach the C128CC directly to any 30 mm cage component with 4-40 mounting taps, allowing for the creation of an enclosed optical path between two 30 mm cage accessories using our aluminum lens tube covers (see photo to the right). The two-piece design allows the cover to be easily removed to verify or correct alignment issues. Two 4-40 cap screws with a 5/64" (2.0 mm) hex are included to mount the clamp.
Click to Enlarge Ø1/2" post holder to an optical table with a BE1 base.
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These base adapters feature a 1/8" (3 mm) hex socket on the bottom for tightening.
The BE1(/M) pedestal base adapter features 1/4"-20 (M6)-threaded studs that fit into the bottom of our standard Ø1/2" post holders or Ø1" post extensions (see photos to the right), converting them into pedestal-style mounts for added stability. Made from solid 303 stainless steel with a 1.25" (31.8 mm) outer diameter, these adapters allow Ø1/2" post holders and Ø1" pillar posts to be used with the CF series of clamping forks, and can be tightened onto the post or post holder using a 1/8" (3 mm) hex.
Alternatively, Thorlabs offers pedestal pillar posts that do not require a BE1(/M) base adapter. We also offer the BE1R(/M) magnetic base adapters (sold individually), which provide additional stability during alignment for temporary setups.
To order an base adapter, or for more options, please see our base adapters page.
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Bottom View of the Captive Screw
Held in Place by the Retainer
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Several Slot Lengths Available
These Clamping Fork Packs are designed to provide exceptional clamping force when used with our Ø1/2" post holders and Ø1" post extensions that have been adapted using the BE1(/M) to pedestal-style mounts. These clamping fork packs can also be used with our pedestal-style Ø1" posts and pedestal-style Ø1/2" post holders without any need for the BE1(/M). Each pack include 5 forks for ordering convenience.
Fabricated from solid 303 stainless steel, all of these clamping forks create three points of contact with the table for high stability. For flexibility in the positioning of post assemblies, the CF038-P5 and CF038C(/M)-P5 forks offer 0.38" (9.5 mm) long counterbored slots, the CF125-P5 and CF125C(/M)-P5 forks offer 1.24" (31.5 mm) long counterbored slots, the CF175-P5 and CF175C-P5 fork packs have 1.75" (44.4 mm) long counterbored slots, and the CF175C/M-P5 fork pack features a 1.76" (44.8 mm) counterbored slot on each fork. The counterbored slots on the CF038-P5, CF125-P5, and CF175-P5 forks are designed for user-supplied 1/4"-20 (M6)-threaded cap screws. The CF038C(/M)-P5, CF125C(/M)-P5, and CF175C(/M)-P5 each include 1/4"-20 (M6)-threaded captive screws which are pre-installed on each fork. Please note that significant over tightening of clamping forks can deform the surface of an optical table, which can cause misalignment of components and decrease stability.
To order individual clamping forks, or for more options, please visit our base adapters and clamping forks page.
Thorlabs' Table Clamps are useful when constructing optomechanical assemblies. Their ability to adapt complex, unforgiving layouts to any mounting hole pattern saves time and headaches, significantly reducing setup times. The design of our clamps makes each one suitable for securing bases and other optomechanical components using 1/4"-20 (M6) cap screws and washers, which are available as part of our Screw Kits. For ordering convenience, the CL5, CL5A, CL2(/M), and CL3(/M), are available here in packs of 5.
The CL5-P5 and CL5A-P5 clamps have a simple L-shape design for use with a wide variety of optomechanical components. Each clamp only requires one 1/4"-20 (M6) cap screw to use. The CL5 can be used to secure components up to 0.50" thick. The additional rounded lip of the CL5A-P5 clamps maintains contact with the top surface of the optomechanic when the clamp is used at higher angles, making it compatible with components up to 0.80" thick.
Both the CL2(/M)-P5, our heavy-duty option, and the CL3(/M)-P5, our more compact version, require two 1/4"-20 (M6) cap screws for each clamp, as seen in the image above. Both of these options feature variable height that depends on the length of the cap screws used. The CL2(/M)-P5 is 1" (25.4 mm) longer than the CL3(/M)-P5, providing maximum torque on the contact surface. The CL3(/M)-P5, on the other hand, is smaller, and significantly reduces footprint on the work surface.
To order an individual clamp, or for more options, please see our table clamps page.
Thorlabs offers a variety of anodized aluminum bases to best utilize space on an optical breadboard. Our most popular bases, the BA1S(/M), BA1(/M), and BA2(/M), are available here in 5 packs.
For close positioning of components, our BA1S(/M)-P5 bases feature the smallest footprint. For increased stability while maintaining a small footprint, the two-slotted BA1(/M)-P5 is a good option. For the greatest stability, consider our BA2(/M)-P5 bases, which offer a larger contact area.
Please note that a 3/8" long, 1/4"-20 (10 mm long M6) cap screw is recommended for attaching post holders to each of our standard mounting bases.
To order an individual base, or for other mounting base options, please see our post holder bases page.
For ordering convenience, many of our Stainless Steel Compact Cage Components are available in packs of 4. These 16 mm cage rods are made from stainless steel and are designed for use with our Compact Series Components. The 4-40 threaded setscrew at each end of the cage rod can be removed, leaving a 4-40 tapped hole. This allows multiple cage rods to be connected end-to-end.
The SRSCA is a stud adapter that will allow any cage assembly to be easily separated when adding or removing components. This adapter has an internal bore on one end that accepts a Ø4 mm SR series rod with its setscrew removed. The mounting stud collar must be tightened using the locking setscrew with a 5/64" (2 mm) hex key to hold the SR rod in place. On the other side of the adapter, there is an externally 4-40 threaded stud that can be threaded into the end of another SR series rod or 4-40 internally threaded cage component.
As seen in the images below, the SRSCA is particularly useful for connecting two internally 4-40 threaded cage system components with Ø4 mm SR series cage rods.
Thread the SR series cage rods directly into the KCB05 16 mm Right-Angle Kinematic Cage Mount as shown above. Then thread four SRSCA adapters into the SC6W Compact 6-Way Cage Cube. Finally, insert the Ø4 mm SR series rods into the internal bores on the SRSCA adapters and secure using the 2-56 locking setscrews.
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For ordering convenience, many of our Stainless Steel Cage Assembly Rods are available in packs of 4. These rods are most commonly used as precision guides for our cage assembly plates and are available with a Ø6 mm diameter for 30 mm or 60 mm cage systems. The 4-40 threaded setscrew at each end of the cage rod can be removed, leaving a 4-40 tapped hole. This allows multiple cage rods to be connected end-to-end.
To order individual assembly rods, or for more length options, please see our cage system construction rods page.
Our ERSCB Adapters enable any cage assembly to be easily separated when adding or removing components. This adapter has an internal bore on one end that accepts a Ø6 mm ER series rod with its setscrew removed. The 8-32 locking setscrew with a 5/64" (2.0 mm) hex must be tightened to hold the ER rod in place. On the other side of the adapter, there is an externally 4-40 threaded stud that can be threaded into the end of another ER series rod or 4-40 internally-threaded cage component.
Traditional fixed optic mounts are available in 5 packs for optic diameters of Ø1/2", Ø1", and Ø2". Each mount in the pack features internal SM threading, and comes complete with one retaining ring per mount for securing the optic in place. Externally threaded lens tubes are available and allow for multi-element optic systems to be attached directly to each fixed lens mount. Each fixed mount features an 8-32 (M4) tapped hole for post mounting.
For small optics (i.e., less than Ø10 mm), we offer stainless steel adapters that allow these optics to be mounted in our SM05-threaded LMR05(/M) mounts. We also offer a line of small optic adapters with external SM1 threading, which can mount optics from Ø5 mm to Ø20 mm in SM1-threaded LMR1(/M) lens mounts.
To order individual optic mounts, or for more options, including mounts for other optic diameters, please see our fixed lens mount page.
Thorlabs' line of Fixed Optical Mounts, available here in packs of 5, hold Ø1/2" (Ø12.5 mm), Ø1" (Ø25.0 mm), or Ø2" (Ø50.8 mm) optics. Each mount features 8-32 (M4) tapped holes at the base, which allow them to be directly attached to our Ø1/2 posts. The double-bored design of the optic cavity provides two stable lines of contact, holding the optic securely in place via a top-located 8-32 (M4) nylon-tipped setscrew. The rear of the optic rests against a small shoulder, which leads to a clear aperture that is nearly as large as the optic itself.
To order individual mounts, please visit our Fixed Optical Mounts page.
Three of our most popular SM-Threaded Retaining Rings are available in multipacks. The SM05-threaded (0.535"-40) SM05RR retaining ring and SM1-threaded (1.035"-40) SM1RR retaining ring are both available in packs of 10, while the SM2-threaded (2.035"-40) SM2RR retaining ring is available in packs of 5. Each ring is made from black-anodized aluminum and is machined with two slots for compatibility with our selection of spanner wrenches.
To order individual retaining rings, or for stress-free, stainless steel, and plastic ring options, see our retaining rings page.
These lever-actuated, continuously variable iris diaphragms are designed to provide smooth operation over many thousands of cycles. The individual steel leaves pivot within a black-anodized aluminum housing. Maximum Aperture sizes range from Ø8 mm to Ø25 mm. Irises are available either unmounted (without mounting holes) or within a black-anodized aluminum housing with a bottom-located 8-32 (M4) setscrew for post mounting.