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Quartz Viewports and Flanges

Quartz Viewports and Flanges

-- Steady & Reliable Manufacturer --

Introduction

Quartz Viewports and Flanges are essential components that provide a transparent, high-purity optical window into closed systems, specifically high-vacuum (HV), ultra-high vacuum (UHV), pressure vessels, and chemical reactors. The primary function is to allow visual inspection, optical sensing, or the passage of UV, visible, or IR light without compromising the sealed environment. These viewports are fabricated by expertly fusing a precision-polished quartz window or disc directly into a compatible metal flange (usually Stainless Steel) or a ground quartz joint. Yancheng Mingyang Quartz Products Co., Ltd. specializes in creating hermetically sealed quartz-to-metal assemblies that maintain leak-tight integrity across extreme temperature and pressure differentials.

The technical challenge lies in the severe mismatch between the CTE (Coefficient of Thermal Expansion) of the metal flange and the fused silica window. We overcome this using a specialized graded seal or a direct, stress-compensated fusion process that guarantees the seal remains vacuum-tight (≤1×10−10 mbar⋅L/s) even after multiple bake-out cycles (up to 250∘C) typical of UHV systems. We supply viewports in various common flange standards, including CF (Conflat), ISO KF, and NW, ensuring drop-in compatibility with existing vacuum equipment. For the window material, Synthetic Fused Silica (JGS1) is often chosen for its superior DUV transmission, allowing optical access down to 170 nm for plasma diagnostics or UV monitoring. Furthermore, we offer viewports with integrated features, such as Anti-Reflective (AR) coatings to maximize light throughput at specific laser wavelengths, and ITO (Indium Tin Oxide) coatings for creating transparent heaters to prevent condensation or for EMI/RFI shielding. Our viewports are essential components in analytical instrumentation, thin-film deposition tools, and space simulation chambers.

By providing certified, leak-tight quartz viewports, we ensure that critical high-vacuum and high-purity environments can be reliably monitored and accessed optically without risk of contamination or pressure loss.

Specification Parameters

ParameterDetails
Flange TypeCF (Conflat), ISO KF, NW (Custom weldable flanges available)
Window MaterialSynthetic Fused Silica (JGS1), Optical Grade (High purity)
Vacuum IntegrityHermetic Seal, Leak Rate <1×10−10 mbar⋅L/s (Helium Leak Tested)
Bake-Out TemperatureUp to 250∘C (CF flanges); Up to 150∘C (KF/Elastomer seals)
Transmission RangeDeep UV (170 nm) to Mid-IR (4.0 μm)Surface FinishOptical Polish (≤60/40 S/D), Flatness ≤λ/4
Flange MaterialStainless Steel (304L or 316L) (Compatible with UHV requirements)
Custom CoatingsAnti-Reflective (AR) coatings for specific laser wavelengths, ITO transparent heater.

The critical performance metric for Quartz Viewports is the Vacuum Integrity, measured by the Helium Leak Rate. Our viewports are guaranteed to meet or exceed UHV standards (<1×10−10 mbar⋅L/s), ensuring long-term system stability without atmospheric contamination. Achieving this integrity requires meticulous control over the quartz-to-metal fusion interface, a complex process due to the thermal expansion mismatch. The Bake-Out Temperature specification is also vital; the CF flange variants are designed to withstand UHV standard bake-outs (200∘C to 250∘C) without compromising the seal, which is necessary to drive off adsorbed atmospheric gases from the chamber walls. For optical quality, the Surface Finish and Flatness of the window are paramount, ensuring clear, undistorted viewing and accurate laser beam passage. Synthetic Fused Silica (JGS1) is chosen for DUV applications (e.g., 185 nm or 193 nm) because its high purity guarantees minimal absorption and UV-induced degradation. Custom services include fusing quartz windows into specialized Kovar or ceramic components for non-standard vacuum systems. Every viewport is individually Helium Leak Tested and certified before shipment.

Applications

  • Ultra-High Vacuum (UHV) Chambers: Optical access for surface science experiments, MBE (Molecular Beam Epitaxy), and thin-film deposition.

  • Plasma Diagnostics: Viewing and spectroscopic ports on plasma etching, CVD reactors, and fusion research devices.

  • Photochemistry and UV Reactors: Providing transparent access for UV light into sealed reaction vessels for catalysis or material curing.

  • Environmental Test Chambers: Sight glasses for high-pressure, high-temperature, or corrosive chemical test environments.

  • Sensor Integration: Used as the mounting and sealing point for in-situ optical sensors, pyrometers, and laser alignment tools.

  • Aerospace Simulation: Windows for vacuum and thermal chambers simulating space environments, requiring minimal outgassing.

The value proposition of our quartz viewports is their ability to provide an optical grade interface under extreme conditions where traditional materials would outgas, leak, or fail due to heat/pressure. The quartz material is not only UV-transparent but also chemically inert, allowing the viewport to be exposed to aggressive plasma or corrosive gases without degradation. Unlike plastic windows, quartz can withstand high-temperature bake-outs, ensuring the ultimate vacuum is achieved and maintained. We offer both demountable (using KF or NW seals) and permanent (using CF flange fusion) solutions, allowing customers flexibility in system design and maintenance. For safety, the quartz window thickness is calculated based on the maximum pressure differential to ensure a high safety factor, and we provide this calculation with the product documentation. Our custom fabrication includes fusing quartz tubes directly into CF flanges, creating permanent, leak-tight feedthroughs for optical fiber or gas lines.

Advantages

  • Certified UHV Integrity: Guaranteed leak rate below 10−10 mbar⋅L/s, essential for critical high-vacuum systems.

  • Wide Spectral Access: Synthetic Fused Silica window material allows high transmission from Deep UV to Mid-IR.

  • Bake-Out Capability: CF flange variants withstand high temperatures to achieve ultimate vacuum levels, minimizing contamination.

  • Chemical and Thermal Resistance: Quartz window is inert to most process gases and stable under extreme temperature gradients.

  • Custom Optical Coatings: Integrated AR, HR, and ITO coatings available to optimize optical performance and manage condensation.

  • Standard Flange Compatibility: Manufactured to ISO and CF standards, ensuring seamless integration into existing vacuum systems.

The core advantage is the provision of a reliable, high-purity, optical gateway into challenging environments, combining the best of quartz's optical properties with the mechanical reliability of standard vacuum flanges.

Payment and Shipping

We accept standard business payments (T/T, L/C). Due to the precise fusion process and UHV testing, custom viewport designs may incur a non-recurring engineering (NRE) fee.

Shipping Protocol for Quartz Viewports: Extreme care to protect the polished window surface and the hermetic seal.

  • Individual Hard Case: Each viewport is placed in a dedicated, secured hard case with internal foam cushioning to protect the window and prevent flange damage.

  • Optical Surface Protection: The quartz window is protected by a temporary, non-abrasive cover (or sealed in a Class100 bag) to maintain its cleanliness and optical quality.

  • Documentation: Shipments include the Helium Leak Test Certificate, pressure calculation safety report, and material CoA.

Lead times for standard KF40 and CF2.75 viewports are 4−6 weeks. Custom flange materials or AR coated viewports require 8−12 weeks.

Frequently Asked Questions (FAQ)

  • Q: What is the main cause of failure in a quartz-to-metal viewport seal?

  • A: The main cause is the CTE mismatch. If the fusion process is not carefully managed (e.g., using a graded seal or stress-relieving geometry), the stress induced during cooling or thermal cycling (bake-out) can cause micro-fractures in the quartz near the seal, leading to a leak.

  • Q: Why do I need a CF flange viewport instead of a cheaper NW KF viewport for UHV?

  • A: NW KF flanges use elastomer (O-ring) seals, which have high outgassing rates and cannot withstand the 250∘C bake-out required for UHV. CF flanges use a copper or metal gasket which is UHV-compatible, can be baked out, and provides a much lower final vacuum limit.

  • Q: Can I use a quartz viewport to view plasma in a reaction chamber?

  • A: Yes, quartz is highly resistant to plasma erosion (sputtering) compared to softer materials. Furthermore, its excellent UV transparency is ideal for optical emission spectroscopy (OES) to diagnose plasma chemistry. We recommend JGS1 synthetic quartz for the best UV performance.

  • Q: How do you prevent condensation on the viewport window during operation?

  • A: We can integrate a thin, transparent ITO (Indium Tin Oxide) coating on the window's surface. ITO is electrically conductive; by applying a low voltage, the window can be gently heated, preventing condensation or frosting without affecting optical transparency.

From Made-in-China to
Global Smart Manufacturing

Yancheng Mingyang Quartz Products Co., Ltd. is a company specializing in the production of quartz and special glass products. Yancheng Mingyang Quartz Products Co., Ltd. is the production plant of Jinzhou Mingde Quartz Glass Co., Ltd. in Jiangsu, Since its establishment, the company has developed rapidly, introduced advanced technology and production equipment at home and abroad, and continuously improved and improved product quality. Relying on its own advantages, we have developed a variety of products suitable for the market and meet the needs of different customers, and solved many urgent production problems for our customers.

The company's products include quartz glass tubes, double-hole quartz glass tubes, quartz glass rods, quartz sheets, sapphire windows, calcium fluoride glass windows, infrared ultraviolet coatings, high-pressure resistant aluminosilicate glass window panels, quartz glass instruments, high borosilicate glass instruments, quartz crucibles, quartz gold-plated tubes, quartz heaters, quartz infrared heating tubes, far-infrared directional radiation heaters ultraviolet germicidal lamps and other special types of quartz glass products.

Yancheng Mingyang Quartz Products Co., Ltd.
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