Grating deployed total-shear 3-beam interference microscopy with reduced temporal coherence

Area of Science:

• Optical Imaging
• Microscopy
• Phase Contrast Imaging

Background:

• Interference microscopy offers quantitative phase information for technical and biomedical applications.
• Conventional systems can suffer from coherent noise and parasitic interference patterns, especially with low-density samples.

Purpose of the Study:

• To propose a compact, common-path, diffraction grating-based interference microscopy system.
• To enable the study of small, sparsely distributed objects like single cells.
• To reduce coherent noise by utilizing reduced temporal coherence light sources.

Main Methods:

• A simple binary amplitude diffraction grating is integrated into a conventional microscope.
• The system operates in a total-shear mode, generating object-reference beam interferograms.
• Three-beam interferograms are generated, containing achromatic second harmonics, allowing the use of low-coherence light sources (e.g., below-threshold laser diode).

Main Results:

• Experimental results validate the analytical description of the proposed interference microscopy method.
• The system demonstrates capabilities for studying both static and dynamic phase objects.
• Automatic computer processing of interferograms is successfully applied.

Conclusions:

• The proposed diffraction grating interference microscope is a compact and effective tool for quantitative phase imaging.
• The system's design mitigates coherent noise, making it suitable for low-density samples and reduced coherence illumination.
• It offers a versatile platform for investigating static and dynamic micro-scale objects.