Calibration Method for Airborne Infrared Optical Systems in a Non-Thermal Equilibrium State

Area of Science:

• Optical Engineering
• Remote Sensing Technology
• Infrared Imaging Systems

Background:

• Airborne infrared optical systems use cooled cameras for radiometry and thermometry.
• Accurate radiometric calibration is vital for quantitative remote sensing data.
• Traditional methods assume thermal equilibrium, causing errors in real-world scenarios.

Purpose of the Study:

• To develop an improved radiometric calibration method for infrared systems operating under non-thermal equilibrium.
• To address the limitations of conventional calibration techniques that assume system thermal equilibrium.
• To enhance the accuracy of quantitative measurements from airborne infrared cameras.

Main Methods:

• Analyzed internal optical temperature variations within the infrared system.
• Developed a simplified model to account for internal stray radiation in non-thermal equilibrium states.
• Implemented an enhanced radiometric calibration method for absolute calibration procedures.

Main Results:

• The proposed method achieved a calibration accuracy exceeding 3.78% for the medium-wave channel.
• Experiments were conducted within a temperature test chamber ranging from -30 °C to 15 °C.
• Maximum temperature measurement error was less than ±1.01 °C.

Conclusions:

• The enhanced radiometric calibration method effectively compensates for internal stray radiation under non-thermal equilibrium.
• This approach significantly improves the accuracy of quantitative radiometry and thermometry for airborne infrared systems.
• The findings are crucial for reliable data acquisition in diverse mission environments.