Photography-based real-time long-wave infrared scattering estimation technique.

Area of Science:

• Optics
• Surface Science
• Infrared Technology

Background:

• Accurate characterization of surface light scattering is crucial for various applications.
• Traditional bidirectional reflectance distribution function (BRDF) measurements are time-consuming.
• Long-wave infrared (LWIR) surface properties are important for thermal imaging and remote sensing.

Purpose of the Study:

• To develop and validate a rapid method for measuring surface scattered light distribution in the LWIR spectrum.
• To assess the applicability of the method for passive, homogeneous surfaces.
• To compare the results with traditional goniometer-based measurements.

Main Methods:

• Utilizing a small set of thermal camera images (six images) captured at varying angles (10°–60°) relative to a thermal light source.
• Employing deconvolution techniques to extract scattering patterns from the image data, accounting for the light source's shape.
• Testing the method on both highly specular (black Masonite) and diffuse (painted drywall) surfaces.

Main Results:

• The proposed method successfully estimates scattering patterns for tested surfaces.
• The technique demonstrates significantly faster data acquisition compared to standard BRDF measurements.
• Achieved errors of ≤3% when comparing estimated scattering distributions to goniometer-based measurements, with limitations for extremely specular surfaces due to speckle noise.

Conclusions:

• Thermal imaging offers an efficient approach for characterizing LWIR surface scattering.
• This method is suitable for homogeneous passive surfaces, providing a valuable alternative for rapid analysis.
• Further investigation may be needed to address challenges with highly specular surfaces and speckle noise.