Active illumination using a digital micromirror device for quantitative phase imaging.

Area of Science:

• Optics and Photonics
• Biomedical Imaging
• Materials Science

Background:

• Quantitative phase imaging (QPI) techniques are crucial for label-free biological and material analysis.
• Traditional active illumination methods can be complex and expensive.
• Controlling illumination angles is key for advanced QPI modalities like synthetic aperture imaging and tomography.

Purpose of the Study:

• To introduce a powerful and cost-effective active illumination method using a digital micromirror device (DMD) for QPI.
• To enable high-resolution 2D synthetic aperture phase imaging and 3D refractive index tomography.
• To demonstrate the method's capability for fast and stable illumination control and high-speed optical tomography.

Main Methods:

• Utilizing a DMD to display binary illumination patterns and generate plane waves with controlled incident angles.
• Employing Mach-Zehnder interferometry to measure complex optical fields of the sample under various illumination angles.
• Reconstructing high-resolution 2D synthetic aperture phase images and 3D refractive index tomograms.

Main Results:

• Demonstrated fast and stable illumination control for imaging colloidal spheres and biological cells.
• Achieved high-resolution 2D synthetic aperture phase imaging and 3D refractive index tomography.
• Showcased high-speed optical diffraction tomography with a tomogram acquisition rate of 100 Hz, enabling 3D Brownian motion measurement.

Conclusions:

• The proposed DMD-based active illumination is a powerful, cost-effective solution for QPI.
• The method facilitates advanced imaging techniques, including high-resolution 2D/3D reconstruction and high-speed tomography.
• This technique opens possibilities for dynamic studies of microscale phenomena, such as Brownian motion.