Ultra-High-Vacuum Fiber Feedthrough CF Flanges

CF Flange Fiber Feedthrough for Ultra-High Vacuum
SMA Terminated on Both Sides
Available for 200 - 1200 nm or 400 - 2400 nm

VC2H2S

CF Flange for
Ø200 µm SMA Fibers

ADASMAV

Vacuum-Compatible Mating Sleeve

VGC10

Copper Gaskets,
10 Pack

Front

Back

VMH6

Flange Mounting Hardware Pack
(6 Bolts, 6 Nuts, & 12 Washers)

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Overview
Insights
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This attenuation data was calculated as a function of wavelength for the fibers used in the UHV fiber feedthrough CF flanges.

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Ultra-High Vacuum Fiber Feedthrough CF Flange Cross-Section

Features

Construction Enables use at Vacuum Levels Down to 1 × 10^-10 Torr
Mates to Ø2.75" (DN40) CF Flanges
Hermetically Sealed Multimode Step-Index Fiber
- Ø100 µm, Ø200 µm, Ø400 µm, or Ø600 µm Core
- High OH (200 - 1200 nm) or Low OH (400 - 2400 nm)
Compatible with Thorlabs' Vacuum-Compatible Multimode Fiber Optic Patch Cables
Bake-Out can be Conducted at Temperatures up to 250 °C
Flange Mounting Hardware Pack and Copper Gaskets Sold Below

Thorlabs' Ultra-High-Vacuum-Compatible Ø2.75" (DN40) Fiber Feedthrough CF Flanges allow for optical coupling into ultra-high-vacuum (UHV) systems down to 10^-10 Torr using SMA905-terminated fiber patch cables and mating sleeves. Each feedthrough incorporates a hermetically sealed step-index multimode optical fiber in a stainless steel shell, provides a low insertion loss of ≤2.3 dB, and can handle optical powers up to 1 W. The flanges are double-bagged to help prevent contamination when transported into a cleanroom environment.

The fiber feedthroughs feature male SMA905 connectors on both sides; mating sleeves may be used to connect fiber patch cables. For the side of the feedthrough that is inside of the vacuum environment, ADASMAV vacuum-compatible SMA-to-SMA mating sleeve, available below, can be used to connect a vacuum-compatible patch cable. Constructed using 304 stainless steel, this adapter is designed to be used within ultra-high vacuum systems (>10^-10 Torr) and features a Ø0.063" (Ø1.6 mm) hole through the body to serve as a vent, allowing trapped gas to escape. When using fiber patch cables in a vacuum environment, ensure that the cables are vacuum compatible.

The laser-welded joints of these flanges provide sturdier construction than traditional adhesives and greatly minimize leak rate. In addition, the locations of these laser welds and the hermetic glass-to-metal seal ensure that only external, easy-to-clean surfaces are directly exposed to the vacuum. Since there is no epoxy on the vacuum side of the feedthrough, there is minimal contamination and gas load on the vacuum system.

The CF-style flange utilizes a knife-edge mechanism to create an airtight seal, allowing for pressures down to 10^-10 Torr when used properly with a copper gasket (sold below). Six 1/4" (M6) through holes allow the these fiber feedthroughs to be bolted onto any standard DN40 CF flange. As the bolts of the mating pair are tightened, the knife edge bites into the copper gasket, deforming it. The compressed copper fills all the machining marks and surface defects, which yields a leak-tight seal. Please note that the copper gasket and bolts must be purchased separately.

Thorlabs also sells CF flange viewports for Ø1" windows, Ø1.5" flat windows, and Ø1.5” wedged windows as well as an extended line of vacuum-compatible parts.

Insights into CF Vacuum Flanges

Scroll down to read about:

Working with CF Vacuum Flanges

Click here for more insights into lab practices and equipment.

Working with CF Vacuum Flanges

This Video Insight provides an overview of CF vacuum flanges and their metal gaskets. Techniques for cleaning the flanges, removing stuck gaskets, and using a star pattern to couple flanges are demonstrated. Tips for working with fiber optic feedthroughs are also provided.

A vacuum coupling that supports operation at ultra-high-vacuum levels ( >10^-8 Torr, >1.33 x 10^-8 mbar, >1.33 x 10^-8 hPa) can be achieved when a metal gasket is compressed between two CF or ConFlat^® flanges. An approach for making this coupling is demonstrated using a CF-flanged fiber optic feedthrough and a port on a CF-flanged-tee. Since the quality of the vacuum seal and the time required to pump the vacuum system down to operating pressure depend on more than just ensuring the bolts are tightened correctly, this demonstration also highlights several practices for working with vacuum components and systems that can help achieve good results.

Damage to the knife edge, an aggressive approach to tightening the bolts, and reusing gaskets can all result in leaky CF vacuum couplings. The techniques demonstrated in this video reduce the risk presented by these factors, which are all related to the limited malleability of the metal gasket. It is important that the knife edges are in pristine condition, since the gasket is not soft enough to fill narrow or abrupt features, such as a nick in a knife edge. An approach of gradually and iteratively tightening the bolts is effective in maintaining a uniform thickness of the gasket around its circumference, while tightening each bolt all at once can result in thickness variations in the gasket that are difficult or impossible to flatten. This is a consequence of the metal gasket’s limited ability to flow and can result in gaps between the gasket and knife edges. Using a new gasket is always recommended. Even a gasket that was only partially compressed during a previous use may not be malleable enough, when reused, to conform to the contours of the knife edges. This is because compression has the effect of strain (work) hardening the metal.

While a leaky vacuum connection can result in time lost to leak checking and re-opening the vacuum system to locate and fix the problem, productive work can also be delayed as a result of broken or malfunctioning components in or attached to the chamber. Due to this, an overview of special considerations for handling and using fiber feedthroughs is also included in this video.

If you would like more information about tips, tricks, and other methods we often use in the lab, we recommend our other Video Insights. In addition, our webinars provide practical and theoretical introductions to our different products.

ConFlat^® is a registered trademark of Agilent Technologies, Inc.

Products Featured During Demonstration
Optical Fiber Feedthrough	1/4-Hard Copper Gaskets	Fiber Inspection Scope	Nitrile Gloves
UHV Fiber Patch Cable	Solvent Dispenser	Fiber Connector Cleaner	Wipes

Date of Last Edit: Sept. 21, 2022

Posted Comments:

Sudipta Nayak (posted 2023-06-09 14:32:27.923)

Hello is it possible to adapt this system for single mode fiber use? We want to connect to single mode pigtail fibers inside the chamber with 10-12 um diameter.

jpolaris (posted 2023-06-14 01:18:32.0)

Thank you for contacting Thorlabs. Requests for custom parts can be made by reaching out to techsupport@thorlabs.com. I have reached out to you to discuss the feasibility of this.

Sylvain Hermelin (posted 2020-09-07 07:48:08.05)

Dear team, I'm looking for a fiber feedthrough that would handle up to 30W, 940nm, 400µm core. I see your standard products seem limited to 1W. Any chance you could provide that? Thanks,

YLohia (posted 2020-09-08 11:03:08.0)

Hello Sylvain, thank you for contacting Thorlabs. Custom items can be requested by emailing your local Thorlabs Tech Support team (in your case techsupport.fr@thorlabs.com). We will reach out to you directly to discuss the possibility of offering this.

DJAMAL IMATOUKEN (posted 2020-01-22 12:59:19.683)

Please is it possible to use Ultra-High-Vacuum Fiber Feedthrough CF Flanges for Ion beam indinced luminescence in Van der graaff accelerator (10-8 torr)?

YLohia (posted 2020-01-23 04:28:49.0)

Hello, these are rated to be used in vacuum levels down to 10^-10 Torr. I have reached out to you directly to discuss your application-specific questions.

schaefer (posted 2016-09-02 09:33:33.39)

Can you provide such a UHV feedthrough, but without connectors directly at the flange? Instead I would like to have a fiber going through the flange with something like 20cm fiber with a FC/PC connector on the vacuum side and 2m on the non-vacuum side (FC/PC). As for fibers: FG105LVA or FG050UGA would be of interest to me.

tfrisch (posted 2016-09-07 01:30:10.0)

Hello, thank you for contacting Thorlabs. We will contact you directly about your application. Acrylate coated fibers will outgas in vacuum, so they should not be used.

andrew.davies.physics (posted 2016-08-26 11:35:25.4)

You should allow custom fibers to be placed in the feedthrough. For instance I would like to use your FG105LVA fiber. The different core size would cause large coupling losses on both ends.

tfrisch (posted 2016-09-01 09:30:49.0)

Hello, thank you for contacting Thorlabs. Unfortunately, FG105LVA has an acrylate coating which will outgas in vacuum. I will reach out to you directly.

user (posted 2014-11-21 10:09:59.43)

Could you make a FC/apc version of this feedthrough?

cdaly (posted 2014-11-25 01:55:12.0)

Response from Chris at Thorlabs: Yes, we should be able to provide this as a custom for the time being and are looking at introducing it as a standard part as well. Please contact us at techsupport@thorlabs.com if you require a quote for this item.

Ø100 µm Ultra-High-Vacuum Feedthrough

Item #	Wavelength Range	Fiber Core Diameter	NA	Vacuum Level	Insertion Loss	Max Optical Power	Max Temperature	Leak Rate
VC2H1S	200 - 1200 nm	100 µm	0.22 ± 0.02	1 × 10^-10 Torr	≤2.3 dB	1 W	250 °C	≤1 x 10^-10 mbar⋅L/s He STD
VC2L1S	400 - 2400 nm	100 µm	0.22 ± 0.02	1 × 10^-10 Torr	≤2.3 dB	1 W	250 °C	≤1 x 10^-10 mbar⋅L/s He STD

Note: Mounting hardware and CF flange copper gasket seals are not included.

Ø200 µm Ultra-High-Vacuum Feedthrough

Item #	Wavelength Range	Fiber Core Diameter	NA	Vacuum Level	Insertion Loss	Max Optical Power	Max Temperature	Leak Rate
VC2H2S	200 - 1200 nm	200 µm	0.22 ± 0.02	1 × 10^-10 Torr	≤2.3 dB	1 W	250 °C	≤1 x 10^-10 mbar⋅L/s He STD
VC2L2S	400 - 2400 nm	200 µm	0.22 ± 0.02	1 × 10^-10 Torr	≤2.3 dB	1 W	250 °C	≤1 x 10^-10 mbar⋅L/s He STD

Note: Mounting hardware and CF flange copper gasket seals are not included.

Ø400 µm Ultra-High-Vacuum Fiber Feedthrough

Item #	Wavelength Range	Fiber Core Diameter	NA	Vacuum Level	Insertion Loss	Max Optical Power	Max Temperature	Leak Rate
VC2H4S	200 - 1200 nm	400 µm	0.22 ± 0.02	1 × 10^-10 Torr	≤2.3 dB	1 W	250 °C	≤1 x 10^-10 mbar⋅L/s He STD
VC2L4S	400 - 2400 nm	400 µm	0.22 ± 0.02	1 × 10^-10 Torr	≤2.3 dB	1 W	250 °C	≤1 x 10^-10 mbar⋅L/s He STD

Note: Mounting hardware and CF flange copper gasket seals are not included.

Ø600 µm Ultra-High-Vacuum Fiber Feedthrough

Item #	Wavelength Range	Fiber Core Diameter	NA	Vacuum Level	Insertion Loss	Max Optical Power	Max Temperature	Leak Rate
VC2H6S	200 - 1200 nm	600 µm	0.22 ± 0.02	1 × 10^-10 Torr	≤2.3 dB	1 W	250 °C	≤1 x 10^-10 mbar⋅L/s He STD
VC2L6S	400 - 2400 nm	600 µm	0.22 ± 0.02	1 × 10^-10 Torr	≤2.3 dB	1 W	250 °C	≤1 x 10^-10 mbar⋅L/s He STD

Note: Mounting hardware and CF flange copper gasket seals are not included.

Vacuum-Compatible SMA to SMA Mating Sleeve

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Vacuum Compatibility Specifications
Vacuum Compatibility as Packaged^a	10^-10 Torr
Materials	304 Stainless Steel
Preparation and Packaging	Chemically Cleaned and Double Vacuum Bagged
Stainless Steel Outgassing Rate at 20 °C	1.8 x 10^-8 Torr-Liters/s/cm²

Prior to placing any components in a vacuum system, we recommend using an appropriate cleaning procedure, which will be dependent on the application, as well as a pre-baking in a bake-out oven to remove moisture and surface volatiles.

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The ADASMAV has a Ø0.063" (Ø1.6 mm) vent hole.

Air-Spaced SMA to SMA Mating Sleeve for Ultra-High-Vacuum Applications
Constructed from 304 Stainless Steel
<1.5 dB Insertion Loss (Typical Loss for a Pair of Ø200 µm Core Multimode Fibers)
Double-Bagged for Cleanroom Environments
Compatible with Thorlabs' Vacuum-Compatible Multimode Fiber Optic Patch Cables

Thorlabs' ADASMAV Mating Sleeve is a vacuum-compatible version of the ADASMA SMA to SMA Mating Sleeve. Constructed using 304 stainless steel, this adapter is designed to be used within ultra-high vacuum systems (>10^-10 Torr) and features a Ø0.063" (Ø1.6 mm) vent hole in the side to allow trapped gases to escape (see image to the right). Unlike the standard version, the ADASMAV is only compatible with SMA905-style connectors. A 304 stainless steel washer and nut are included for custom mounting.

Additional Vacuum-Compatible Components
Many of our patch cables can be special ordered for vacuum use. Contact Tech Support for details.

Vacuum Compatibility Information
Our vacuum-compatible adapter is chemically cleaned and prepared for vacuum applications before packaging. It is compatible directly out of the packaging with vacuum environments down to 10^-10 Torr. With additional cleaning and processing, it can be used at even lower pressures, only limited by the outgassing rate of the stainless steel (see the table above). The material properties of the stainless steel and the cleaning methods completed by the end user should be used to determine the appropriateness of these products and materials in a specific vacuum system. Please note that using caps or panels not rated for vacuum applications with the ADASMAV is not recommended.

We also offer other vacuum-compatible components which may be used in vacuum applications.

CF Flange Copper Gaskets and Mounting Hardware

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VGA10 Copper Gasket Installed on VPCHW42-C Viewport

VMH6 Stainless Steel (18-8) Mounting Hardware Set Includes:
- Six Bolts (Silver-Plated, 1/4"-28 x 1.50", 12-Point Heads)
- Six Nuts and Twelve Washers
Single-Use Copper Gaskets for Forming a Seal Between Ø2.75" CF Flanges
- 101 Copper Alloy (99.99% Pure), OFHC (Oxygen-Free High Conductivity)
- VGC10: 1/4-Hard Copper Gaskets
- VGA10: Annealed Copper Gaskets

Thorlabs offers mounting hardware and single-use copper gaskets for mating Ø2.75" CF flanges. These flanges utilize a knife-edge mechanism to create an airtight seal between mating pieces. To create the seal, a copper gasket is most often employed. As the bolts of the mating pair are tightened, the knife edge bites into the copper gasket, deforming it. The extruded metal fills all the machining marks and surface defects, which yields a leak-tight seal.

1/4-hard and annealed copper gaskets are sold in sets of 10. We recommend the 1/4-hard copper gaskets for most applications; for more delicate devices, such as viewports, we recommend using the softer annealed copper gaskets to lower the chance of deformation in the optic due to stress in the flange. The set of stainless steel mounting hardware includes six silver-plated bolts, six nuts, and twelve washers. The silver plating on the bolts acts as a lubricant to prevent galling between the stainless steel surfaces of the bolt and the nut.

Instructions
First ensure the knife-edge mating surfaces of the CF flanges are free from debris or scratches. Then choose the desired bolt hole orientation and insert the gasket, aligning leak-test grooves on the flanges if present. Slide a washer onto the bolt, insert the bolt through the flanges, and add another washer before screwing on the nut. Hand tighten each bolt, then use two wrenches to hold the bolt head and turn the nut. Tighten the nuts gradually in 1/8 to 1/4 turn increments in an alternating crisscross star pattern until the desired tightness is reached. Following these steps will result in a reliable seal with even gasket compression and deformation.