Ensuring long-term stability of infrared camera absolute calibration

Area of Science:

• Infrared technology
• Optical engineering
• Detector physics

Background:

• Absolute calibration of cryogenic infrared cameras (3-5 µm and 8-10 µm) is unstable, requiring frequent recalibration.
• Performance degradation, including reduced signal-to-noise ratio, limits the utility of infrared imaging.
• Instability is often attributed to detector response state changes and stray light, not proximity electronics.

Purpose of the Study:

• To identify the root cause of calibration instability in cryogenic infrared cameras.
• To demonstrate a method for stabilizing infrared camera calibration.
• To validate long-term calibration retention.

Main Methods:

• Investigated the role of proximity electronics in calibration instability.
• Identified the initial voltage of the integrating capacity as a key instability parameter.
• Developed a method to measure and account for this initial voltage.

Main Results:

• Detector performance is not the primary cause of calibration instability.
• The initial voltage of the integrating capacity in proximity electronics is a significant factor.
• Accounting for this parameter allows for sustained calibration validity.

Conclusions:

• Cryogenic infrared camera calibration instability originates from proximity electronics, not detectors.
• A simple measurement of initial voltage stabilizes calibration.
• This method ensures a 3-5 µm camera's calibration remains valid for at least one month.