UV Talk Letter Vol. 5

Importance of the Topic

Integrating spheres enable precise measurement of solid and scattering samples by capturing and uniformly diffusing light within a spherical chamber. They are essential in UV-Vis and IR spectrophotometry for accurate transmittance, reflectance, haze and solar performance evaluations of materials that scatter, refract or absorb light.

Objectives and Overview of the Paper

This text introduces the principles and practical applications of integrating spheres in spectrophotometry, outlines standardized methods for solar transmittance and reflectance per JIS R3106, clarifies the distinction between relative and absolute reflectance measurements, and presents recent instrumentation advances including Shimadzu’s AA-7000 atomic absorption spectrophotometer series.

Methodology and Instrumentation

Integrating Sphere Measurements:

• Principle: A barium sulfate–coated sphere scatters incoming light, directing it uniformly to the detector aperture.
• Transmittance: Baseline correction with empty sphere or white standard; measurement of total and scattered components; haze determined by excluding direct beam via light trap.
• Reflectance: Relative reflectance against a standard (barium sulfate or aluminum mirror) at 0° for diffuse only or 8° for total (diffuse plus specular) reflectance.

Solar Performance per JIS R3106:

• Visible transmittance/reflectance (380–780 nm) and solar transmittance/reflectance (300–2500 nm) calculated using weighted spectral data.
• Normal emittance (5–50 μm) measured by IR spectrophotometer with specular reflectance accessory and converted with standardized equations.

Instrumentation

• UV-Vis spectrophotometer with integrating sphere for transmittance, reflectance and haze.
• UV-Vis-NIR spectrophotometer and dedicated software for solar measurement.
• IR spectrophotometer with specular reflectance attachment for normal emittance.
• Shimadzu AA-7000 series atomic absorption spectrophotometers featuring double-beam optics, high-sensitivity furnace, rapid dual-atomizer switching and advanced safety sensors.

Key Results and Discussion

Example measurements on four commercial glass types revealed significant variation in UV-Vis-NIR spectra across samples, while IR reflectance remained similar. Total versus scattered transmittance and diffuse versus total reflectance modes demonstrate the sphere’s ability to isolate desired optical components. Absolute reflectance measurements yield lower, instrument‐independent values compared to relative methods, enhancing inter‐instrument consistency.

Advantages and Practical Uses of the Method

• Enables accurate analysis of semi-transparent films, lenses, coatings and turbid suspensions.
• Standardized solar performance assessment for building glazing, films and paints.
• Haze measurements essential for quality control in plastics and optics.

Conclusion

Integrating spheres expand the capability of spectrophotometry to handle scattering, refractive and optically complex samples, ensuring reliable transmittance, reflectance, haze and emittance data. Compliance with JIS standards facilitates consistent evaluation of energy‐efficient materials.

Future Trends and Potential Applications

Advances may include larger spheres for improved diffusion, enhanced noise suppression techniques, integrated calibration routines and specialized software for rapid solar performance analysis. Emerging applications span sustainable building materials, advanced coatings, photovoltaic research and environmental monitoring.

References

• Shimadzu Application News No. A396: Daylight Transmittance Application Data of Glass Plate
• Shimadzu Application News No. A404: Glass Plate Analysis in Accordance with JIS R3106
• Shimadzu Application News No. A412: Analysis of Adhesive Films for Glazings Conducted in Accordance with JIS A5759