A laboratory goniometer system for measuring reflectance and emittance anisotropy

Area of Science:

• Earth and Environmental Sciences
• Optical Physics
• Remote Sensing Technology

Background:

• Goniometers are crucial for measuring directional optical properties.
• Existing laboratory goniometers can be time-consuming for comprehensive hemispherical measurements.
• Understanding anisotropic reflectance and emittance is vital for accurate remote sensing data interpretation.

Purpose of the Study:

• To describe a novel laboratory goniometer system for multi-angular measurements.
• To highlight the system's speed and flexibility in assessing anisotropic properties.
• To demonstrate the system's utility for soils, leaves, and small canopies.

Main Methods:

• Utilized a commercially available robotic arm for automated data acquisition over the full hemisphere.
• Integrated a spectrometer for hemispherical and horizontal plane measurements.
• Incorporated a thermal camera for directional thermal emittance observations.

Main Results:

• The robotic arm significantly reduced measurement time compared to conventional goniometers.
• The system successfully assessed anisotropic reflectance and emittance for various sample types.
• Showcased diverse measurement capabilities through three distinct experimental setups.

Conclusions:

• The developed laboratory goniometer system offers enhanced speed and flexibility for optical measurements.
• Future research can link measured anisotropy with physical models and field data for remote sensing.
• This instrument provides significant added value to existing laboratory goniometry capabilities.