Axially-Offset Differential Interference Contrast Correlation Spectroscopy

A method of obtaining intensity and quantitative phase information representative of the particle size distributions in nanocrystal suspensions, comprising:

• a) providing a first light beam along a first axis to a first micro-retarder array to generate polarization wavefront shaped light;
• b) applying the polarization wavefront shaped light to an objective configured to focus two orthogonally polarized components of the polarization wavefront shaped light to produce first and second axially offset foci along the first axis;
• c) disposing a sample having particles in suspension in at least one of the first and second axially offset foci to produce a measurement optical signal having phase and intensity values corresponding to at least some of the particles in suspension;
• d) applying the measurement optical signal to a second objective and a second micro-retarder to generate recombined light;
• and
• e) generating electrical measurement signals representative of the measurement optical signal from the recombined light over time;
• and
• f) determining intensity and quantitative phase information as a function of time based on the electrical measurement signals.