Multipass wide-field phase imager

Area of Science:

• Optical Imaging
• Biophysics
• Photonics

Background:

• Optical imaging seeks enhanced sensitivity and resolution for practical applications.
• Existing techniques face limitations in low-light conditions and phase sensitivity.

Purpose of the Study:

• To develop a versatile interference contrast imaging technique with high phase sensitivity and a large field-of-view.
• To improve imaging performance for photo-sensitive and biological samples.

Main Methods:

• Utilized a self-imaging non-resonant cavity for multi-round photon probing (transmissive or reflective).
• Employed a single-photon camera with time-of-flight and pixel-off gating for individual round phase profile resolution.
• Implemented novel data processing combining multi-round sample profiles to reduce measurement noise.

Main Results:

• Achieved over a four-fold reduction in phase measurement noise compared to single-round imaging.
• Demonstrated phase measurement noise values close to theoretical predictions for optimal cavity configurations.
• Observed good agreement with theoretical predictions, especially at low numbers of rounds.

Conclusions:

• The developed technique offers a significant improvement in phase sensitivity and noise reduction for optical imaging.
• Its ease of use, without requiring lasers or cavity lock-in, makes it suitable for inspecting sensitive samples.
• The multi-round photon probing strategy effectively enhances imaging performance under low light conditions.