Design considerations for advanced MWIR target acquisition systems.

Area of Science:

• Optics and Photonics
• Infrared Sensor Technology
• System Engineering

Background:

• Mid-wave infrared (MWIR) sensors are critical for various applications, but their performance is constrained by system parameters and environmental factors.
• The Fλ/d parameter, representing the ratio of f-number, effective wavelength, and detector pitch, is a key factor in MWIR sensor design and optimization.
• Previous research suggests a design point of Fλ/d ≈ 2.0 for MWIR systems, particularly for detecting targets with significant temperature differences.

Purpose of the Study:

• To provide a framework for optimizing mid-wave infrared (MWIR) sensor performance based on the Fλ/d parameter.
• To investigate the impact of system limitations, environmental conditions, and target characteristics on optimal Fλ/d selection.
• To guide the development of next-generation MWIR sensors with improved sensitivity and smaller detectors.

Main Methods:

• Analysis of MWIR sensor range performance as a function of the Fλ/d parameter.
• Evaluation of detector-limited and optics-limited operational regimes based on Fλ/d values.
• Consideration of factors such as optical aberrations, noise sources (background shot noise, dark current, read noise), and atmospheric attenuation.

Main Results:

• For diffraction-limited systems, acquisition range is detector-limited when Fλ/d < 1 and optics-limited when Fλ/d > 2.0.
• Range performance is a combination of detector and optics resolution limits when 1 < Fλ/d < 2.0.
• Optimal Fλ/d for MWIR sensors detecting low-contrast targets (ΔT ≈ 0.1 K) is approximately 1.5, due to photon-starved conditions and the use of sensor gain.

Conclusions:

• The Fλ/d parameter provides a valuable metric for optimizing MWIR sensor design and predicting range performance.
• System component characteristics, environmental factors like atmospheric attenuation, and target contrast significantly influence the optimal Fλ/d.
• Future MWIR sensor development should focus on smaller detectors, larger arrays, and enhanced sensitivity to enable Fλ/d-based optimization for diverse operational scenarios.