Coded aperture imaging: predicted performance of uniformly redundant arrays

Area of Science:

• Optics
• Image Reconstruction
• Array Imaging

Background:

• Uniformly redundant arrays (URAs) possess autocorrelation functions with perfectly flat sidelobes.
• URAs integrate the high-transmission properties of random arrays with the flat sidelobe benefits of nonredundant pinhole arrays.

Purpose of the Study:

• To develop a general expression for the signal-to-noise ratio (SNR) of URAs.
• To derive an expression for optimum aperture transmission for URAs.
• To compare the performance of URA imaging systems with single pinhole cameras.

Main Methods:

• Developed a general SNR expression for URAs based on object type and aperture design parameters.
• Derived an optimum aperture transmission expression from the SNR equation.
• Compared URA imaging performance against single pinhole camera limitations.

Main Results:

• The SNR expression allows for optimization of URA design parameters.
• The only known 2-D URAs have a transmission of (1/2), which results in a maximum SNR reduction of 30%.
• URA imaging yields virtually uniform noise, significantly improving image quality over single pinhole cameras, particularly for bright objects and in high-background noise scenarios.

Conclusions:

• URAs provide superior image quality compared to single pinhole cameras, especially under high background noise conditions.
• The performance improvement of URAs is dependent on object intensity distribution and detector noise levels.
• The (1/2) transmission of current 2-D URAs is a minor limitation, with minimal impact on achievable SNR.