An Integrating Sphere System for Measuring Average Reflectance and Transmittance

John M. Davies, Walter Zagieboylo

The optical properties of systems for protection against thermal radiation play a primary role in determining their effectiveness. An improved integrating sphere provides for determination of the average reflectance and transmittance of materials, each in a single measurement; this average is the correctly weighed average for the source. The sphere coating of pure aluminum oxide approaches the ideal of a perfectly diffuse reflectance, essentially constant over the wavelength range of interest with improved permanence. The somewhat low average reflectance of this coating also reduces the error due to nonuniform spectral response. Results obtained with this device and by other methods agree. This instrument is especially useful where the same source is used for measurement of optical properties and for exposure of materials to intense radiation. © 1965 Optical Society of America.

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Materials
Curve 1
Temperature K: 298 Wavelength Range, μ: 0.300-1.000 Geometry θ θ' ω': 0° ? 2π Composition (weight percent), Specifications and Remarks: Sand blasted.
Curve 1
Temperature K: 298 Angular Range, θ: 0-80 Geometry θ θ' ω': 45° θ' Composition (weight percent), Specifications and Remarks: Sand blasted; φ=0°, φ'=0°; tungsten filament lamp source.
Curve 2
Temperature K: 298 Angular Range, θ: 0-20 Geometry θ θ' ω': 45° φ' Composition (weight percent), Specifications and Remarks: Above specimen and conditions except φ' = 180°.
Curve 3
Temperature K: 298 Angular Range, θ: 0-80 Geometry θ θ' ω': 45° θ' Composition (weight percent), Specifications and Remarks: Different sample, same as curve 2 specimen and conditions.
Curve 4
Temperature K: 298 Angular Range, θ: 0-20 Geometry θ θ' ω': 45° θ' Composition (weight percent), Specifications and Remarks: Above specimen and conditions except φ' = 180°.
Curve 5
Temperature K: 298 Angular Range, θ: 0-80 Geometry θ θ' ω': 45° θ' Composition (weight percent), Specifications and Remarks: Curve 4 specimen and conditions except green filter used.
Curve 6
Temperature K: 298 Angular Range, θ: 0-20 Geometry θ θ' ω': 45° θ' Composition (weight percent), Specifications and Remarks: Above specimen and conditions except φ' = 180°.
Curve 7
Temperature K: 298 Angular Range, θ: 0-80 Geometry θ θ' ω': 45° θ' Composition (weight percent), Specifications and Remarks: Curve 4 specimen and conditions except amber filter used.
Curve 8
Temperature K: 298 Angular Range, θ: 0-20 Geometry θ θ' ω': 45° θ' Composition (weight percent), Specifications and Remarks: Above specimen and conditions except φ' = 180°.
Curve 9
Temperature K: 298 Angular Range, θ: 0-80 Geometry θ θ' ω': 45° θ' Composition (weight percent), Specifications and Remarks: Curve 4 specimen and conditions except blue filter used.
Curve 10
Temperature K: 298 Angular Range, θ: 0-20 Geometry θ θ' ω': 45° θ' Composition (weight percent), Specifications and Remarks: Above specimen and conditions except φ' = 180°.
Curve 11
Temperature K: 298 Angular Range, θ: 0-80 Geometry θ θ' ω': 65° θ' Composition (weight percent), Specifications and Remarks: Different sample, same as curve 2 specimen and conditions.
Curve 12
Temperature K: 298 Angular Range, θ: 0-40 Geometry θ θ' ω': 65° θ' Composition (weight percent), Specifications and Remarks: Above specimen and conditions except φ' = 180°.
Curve 1
Temperature, K: 298 Wavelength Range, µm: 0.300-1.000 Geometry θ θ' ω: ~0° 2π Composition (weight percent), Specifications, and Remarks: Sapphire (0.25 mm thick); substrate unknown; flame-sprayed.
Curve 2
Temperature, K: 298 Wavelength Range, µm: 0.300-1.000 Geometry θ θ' ω: ~0° 2π Composition (weight percent), Specifications, and Remarks: Aluminum oxide; substrate unknown; aluminum oxide commercially pure; flame sprayed.
Curve 3
Temperature, K: 298 Wavelength Range, µm: 0.300-0.979 Geometry θ θ' ω: ~0° 2π Composition (weight percent), Specifications, and Remarks: Sapphire (0.25 mm thick); substrate unknown; flame sprayed.
Curve 4
Temperature, K: 298 Wavelength Range, µm: 0.300-0.995 Geometry θ θ' ω: ~0° 2π Composition (weight percent), Specifications, and Remarks: Similar to curve 6 specimen and conditions except 0.13 mm thick.
Curve 5
Temperature, K: 298 Wavelength Range, µm: 0.300-0.993 Geometry θ θ' ω: ~0° 2π Composition (weight percent), Specifications, and Remarks: Similar to curve 6 specimen and conditions except 0.08 mm thick.
Curve 6
Temperature, K: 298 Wavelength Range, µm: 0.300-0.994 Geometry θ θ' ω: ~0° 2π Composition (weight percent), Specifications, and Remarks: Similar to curve 6 specimen and conditions except 0.05 mm thick.
Curve 7
Temperature, K: 298 Wavelength Range, µm: 0.300-0.994 Geometry θ θ' ω: ~0° 2π Composition (weight percent), Specifications, and Remarks: Similar to curve 6 specimen and conditions except 0.025 mm thick
Curve 1
Temperature K: 298 Wavelength, µm: ~0.56 Angular Range, °: -20–+80 Geometry θ θ': 45° θ' Composition (weight percent), Specifications and Remarks: Sapphire (~0.38 mm thick); aluminum substrate; substrate sand blasted; sapphire pure; flame sprayed; measured in plane of incidence; tungsten filament source used with green filter (λ ~0.56 µm).
Curve 2
Temperature K: 298 Wavelength, µm: ~0.46 Angular Range, °: -20–+80 Geometry θ θ': 45° θ' Composition (weight percent), Specifications and Remarks: Curve 1 specimen and conditions except used blue filter (λ ~0.46 µm).
Curve 3
Temperature K: 298 Wavelength, µm: ~0.59 Angular Range, °: -20–+80 Geometry θ θ': 45° θ' Composition (weight percent), Specifications and Remarks: Curve 1 specimen and conditions except used amber filter (λ ~0.59 µm).
Curve 1
Temperature, K: 298 Angular Range, °: -40–+80 Geometry θ θ': 65° θ' Composition (weight percent), Specifications, and Remarks: Sapphire; aluminum substrate; substrate sandblasted; sapphire pure; flame sprayed; measured in plane of incidence; tungsten source.
Curve 2
Temperature, K: 298 Angular Range, °: -25–+80 Geometry θ θ': 45° θ' Composition (weight percent), Specifications, and Remarks: Aluminum oxide; aluminum substrate; substrate sandblasted; aluminum oxide commercially pure; flame sprayed; measured in plane of incidence; tungsten source.
Curve 3
Temperature, K: 298 Angular Range, °: -40–+80 Geometry θ θ': 65° θ' Composition (weight percent), Specifications, and Remarks: Aluminum oxide; aluminum substrate; substrate sandblasted; aluminum oxide commercially pure; flame sprayed; measured in plane of incidence; tungsten source.
Curve 4
Temperature, K: 298 Angular Range, °: -40–+80 Geometry θ θ': 45° θ' Composition (weight percent), Specifications, and Remarks: Sapphire (~0.38 mm thick); aluminum substrate; substrate sandblasted; sapphire pure; flame sprayed; measured in plane of incidence; tungsten source.
Curve 1
Temperature, K: 298 Angular Range, °: -25–+80 Geometry θ θ' ω: 45° θ' Composition (weight percent), Specifications, and Remarks: MgO (~0.76 mm thick); substrate unknown; θ=45°, θ'=θ'; tungsten filament lamp source; measured in plane of incidence.