Optical Fiber Feedthrough for a Vacuum Chamber

In a vacuum chamber, a flange is used to feed an optical fiber through while maintaining the chamber’s vacuum, enabling optical signal transmission between its interior and exterior. One approach is to position fiber optic cables in through holes of a vacuum flange and securing them with epoxy resin adhesives. However, these rigid connections are prone to leaks over time or as a result of bake-out processes, necessitating frequent replacements of both flange and the fiber optical cable. Another approach is a flange with a radially compressed elastomer gasket through which an optical fiber is passed. However, this has drawbacks, such as the limited sealing effectiveness of radially compressed gaskets and the risk of transmission loss due to the radial pressure applied to the optical fiber. Therefore, an improved feedthrough is needed ensuring that the airtightness of the vacuum chamber reduces the need for part replacements, and minimizes transmission loss.

An optical fiber feedthrough for transmitting multiple optical fibers between the interior and exterior of a vacuum chamber includes a compression device, such as a clamping mechanism, which compresses sealing elements arranged within the passage openings to create a pressure-tight seal around each fiber (Figure 1 provides a schematic of the optical fiber feedthrough). The sealing element, which is axially compressed between the compression device and a flange sealing receptacle, expands in the radial direction of the optical fiber, securing it in place. For example, the compression device may comprise a metal compression plate and an interposed sleeve arranged between the compression plate and the sealing element (as shown in Figure 2). The compression plate provides an axial force along the passage openings, which is transmitted to the sealing elements via the interposed sleeves, exerting an radial inward compression around each optical fiber. In this way, this invention enables a vacuum-tight feedthrough of multiple optical fibers with low transmission loss.

• High airtightness: Ensures secure sealing for sustained vacuum, reducing leakage risk.
• Reduced maintenance: Minimizes the need for flange and cable replacements, lowering operational costs.
• Multiple-fiber feedthrough: Supports the secure passage of multiple optical fibers simultaneously, enhancing efficiency and versatility.
• Reduced transmission loss: Precise, controlled compression minimizes pressure on the optical fibers, maintaining high signal quality and reducing transmission loss.

• Spectroscopy and analysis: Enables precise optical signal transfer for spectroscopic analysis of materials within a vacuum environment, such as in mass spectrometry and X-ray spectrometry.
• Imaging and Real-Time Monitoring: Supports optical imaging and monitoring in vacuum conditions, crucial for plasma research, particle accelerators, and other advanced physics applications.
• Laser processing and material modification: Facilitates laser delivery in vacuum-based material processing systems, used for creating microstructures and altering material properties.

DE application (DE10 2023 121 227.3), pending in EP and US
Priority date: 09.08.2023