Quantitative retardance imaging of biological samples using quadriwave lateral shearing interferometry

Area of Science:

• Biophysics
• Optical Imaging
• Cell Biology

Background:

• Birefringence and linear retardance are crucial optical properties of anisotropic biological materials.
• Quantitative measurement of these properties in living samples is challenging.
• Label-free imaging techniques are highly desirable for studying cellular structures.

Purpose of the Study:

• To introduce a new high-resolution quantitative phase imaging technique for measuring linear retardance and birefringence.
• To demonstrate the technique's compatibility with living biological samples.
• To characterize the anisotropic properties of collagen fibers and living cells.

Main Methods:

• Utilized a high-resolution quadri-wave lateral shearing interferometer.
• Combined quantitative phase imaging with varying polarization excitation.
• Generated retardance images to analyze local retardance and structural anisotropy.

Main Results:

• Achieved quantitative birefringence measurements on collagen fibers, yielding a value of (3.4 ± 0.3) · 10(-3).
• Successfully imaged the anisotropic cytoskeleton of living cells without the need for labeling.
• Demonstrated the technique's ability to provide information on local retardance and structural organization.

Conclusions:

• The developed technique offers a label-free, quantitative method for assessing birefringence and retardance in biological specimens.
• This approach is suitable for studying the structural and optical properties of anisotropic components in both isolated tissues and living cells.
• The method provides valuable insights into the organization of structures like the cytoskeleton in their native, living state.