Acoustic viewport CF

Overview
CF-flanged sapphire viewports provide a hermetic, vacuum-compatible optical window for HV and UHV systems. Constructed from high-purity single-crystal sapphire and 304 stainless steel flanges, these viewports are vacuum-brazed and designed for repeated bake-out cycles up to 350°C. Crystal orientation is normal to the optical axis (90°). UV-grade sapphire is used for diameters ≤ 1".

Specifications
Materials:
Flange: 304 Stainless Steel
Glass substrate: Sapphire (99.99% Al2O3)
Seal: Vacuum-brazed

Features

• Single-crystal sapphire substrate
• Mounting orientation: 0–90°
• Ultraviolet (UV) and standard optical grades
• Optically polished faces
• UHV-compatible construction
• Bakeable to 350°C for repeated cycles
• Stainless steel / NiFe flange options
• Custom sizes and configurations available on request

Sapphire Properties
Chemical: Sapphire (99.99% Al2O3)
Mechanical:
Density: 3.97 g/cc
Hardness: 22.5 GPa
Modulus of Elasticity: 470 GPa
Flexural Strength: 690 MPa
Compressive Strength: 2940 MPa
Electrical:
Dielectric Strength: 48 ac V/mm
Dielectric Constant: 9.3 (@ 1 MHz)
Volume Resistivity: 10^14 ohm-cm
Thermal:
Coefficient of Thermal Expansion: 5.3 x10^-6/°C
Thermal Conductivity: 41 W/(m*K)
Specific Heat: 0.75 x10^3 J/(Kg*K)
Maximum Working Temperature: 1900 °C
Optical:
Index of Refraction: 1.762

Note
All sapphire viewports are fragile; handle and mount with extreme care to avoid damage.

Technical specifications

• Product: CF Flanged Sapphire Viewports
• Flange material: 304 Stainless Steel
• Glass substrate: Sapphire (99.99% Al2O3)
• Seal type: Vacuum brazed
• Crystal orientation: normal to optical axis (90°)
• Temperature: bakeable to 350°C
• Maximum working temperature (sapphire): 1900 °C
• Positioning/direction: 0–90°
• Grades: Ultraviolet (UV) and regular; UV grade for viewports ≤ 1" diameter
• Finish: Optically polished substrate faces
• Construction: UHV compatible; stainless steel / NiFe construction
• Mechanical properties: Density 3.97 g/cc; Hardness 22.5 GPa; Modulus of Elasticity 470 GPa; Flexural Strength 690 MPa; Compressive Strength 2940 MPa
• Electrical properties: Dielectric Strength 48 ac V/mm; Dielectric Constant 9.3 (@1 MHz); Volume Resistivity 10^14 ohm-cm
• Thermal properties: CTE 5.3 x10^-6/°C; Thermal Conductivity 41 W/(m*K); Specific Heat 0.75 x10^3 J/(Kg*K)
• Optical: Index of Refraction 1.762
• Custom solutions available by customer request