Transport-of-intensity phase imaging using commercially available confocal microscope

Area of Science:

• Biophysics
• Optical Microscopy
• Cell Biology

Background:

• Confocal microscopy is vital for high-resolution biological imaging, particularly for fluorescence in living cells.
• Phase information offers valuable insights, including physical parameter measurement and wavefront correction, but is absent in commercial confocal systems.
• Existing confocal microscopes lack integrated phase imaging capabilities.

Purpose of the Study:

• To adapt commercially available confocal microscopes for quantitative phase imaging (QPI).
• To introduce phase imaging functionality without requiring hardware modifications to existing microscopes.
• To enable biologists to measure phase information using their current confocal microscopy setups.

Main Methods:

• Phase imaging was implemented using the transport of intensity equation (TIE).
• The method leverages the bright-field imaging module of standard confocal microscopes.
• No physical modifications to the off-the-shelf confocal microscope were necessary.

Main Results:

• The feasibility of TIE-based QPI was successfully demonstrated on a microlens array.
• Phase imaging was validated using living plant cells (moss) and mammalian cultured cells.
• Multimodal imaging combining fluorescence and phase information was achieved.

Conclusions:

• Quantitative phase imaging (QPI) is achievable with commercially available confocal microscopes using the TIE technique.
• This method provides a non-invasive way to measure physical properties like dry mass, viscosity, and temperature in cells.
• Future applications include aberration correction and scattering cancellation through phase fluctuation compensation.