Fluorescence lifetime imaging with distance and ranging using a miniaturised SPAD system

Area of Science:

• Biomedical Engineering
• Optical Imaging
• Photonics

Background:

• Miniaturized imaging systems are crucial for in-situ diagnostics and research.
• Time-gated single-photon avalanche diode (SPAD) arrays offer advanced imaging capabilities.
• Existing systems often lack portability and multi-modal functionality.

Purpose of the Study:

• To develop and demonstrate a compact, chip-on-tip imaging system.
• To enable high-frame-rate widefield fluorescence imaging (WFLIm).
• To integrate simultaneous WFLIm and time-of-flight measurements (FLImDAR).

Main Methods:

• Utilized a miniaturized "chip-on-tip" system with a time-gated SPAD array.
• Developed two system versions with different fields of view and working distances.
• Tested WFLIm on material contrast and ovine lung tissue autofluorescence.
• Evaluated FLImDAR for 3D object separation and scene reconstruction.

Main Results:

• Achieved frame rates >2 Hz in WFLIm mode with material contrast.
• Obtained WFLIm images of ovine lung autofluorescence at ~1 Hz.
• Demonstrated 4 mm resolution for object separation using FLImDAR.
• Successfully performed scene reconstruction on lung tissue.

Conclusions:

• The developed system is the smallest published chip-on-tip WFLIm system.
• This work represents the first compact, portable demonstration of the FLImDAR technique.
• The system shows significant potential for advanced biomedical imaging applications.