Efficient averaging spheres for visible and ultraviolet wavelengths.

Area of Science:

• Optical Engineering
• Photometry
• Spectroscopy

Background:

• Traditional integrating spheres face challenges with efficiency, particularly in ultraviolet (UV) spectral regions due to lower wall reflectance.
• Accurate photometric measurements require efficient light collection and averaging properties across a wide spectral range.

Purpose of the Study:

• To theoretically analyze and design an averaging sphere optimized for high efficiency across visible and near-UV wavelengths.
• To investigate methods for extending the utility of the averaging sphere into the deep UV region (below 300 nm).

Main Methods:

• Theoretical analysis to establish design criteria for optimizing sphere efficiency.
• Construction of an averaging sphere utilizing a barium-sulfate target.
• Integration of a fluorescent wavelength converter for UV applications below 300 nm.

Main Results:

• The constructed barium-sulfate averaging sphere demonstrates 80-90% efficiency in the visible spectrum.
• The sphere maintains 30% efficiency at 300 nm, suitable for near-UV work.
• With a fluorescent wavelength converter, the sphere achieves 20% efficiency between 200-300 nm and 50% in the visible, while retaining averaging properties for high-accuracy photometry.

Conclusions:

• The optimized averaging sphere design provides high efficiency and excellent averaging properties for visible and near-UV applications.
• The incorporation of a fluorescent wavelength converter effectively extends the sphere's utility into the deep UV range.
• This versatile integrating sphere design supports high-accuracy photometric measurements across a broad spectral range.