Digital defocus aberration interference for automated optical microscopy

Area of Science:

• Biomedical Imaging
• Optical Microscopy
• Microscopy Automation

Background:

• Automated optical microscopy requires robust autofocusing for high-throughput imaging.
• Conventional autofocusing methods face challenges with complexity, generalizability, thick samples, and speed.
• Defocus significantly impacts image quality in microscopy.

Purpose of the Study:

• To develop an automatic, efficient, and generalizable method for defocus detection in optical microscopy.
• To overcome limitations of existing autofocusing techniques.
• To enhance image quality and throughput in automated microscopy.

Main Methods:

• Utilized digitally summed Fourier spectra from two-angle illumination images to detect interference-like fringe modulation.
• Developed a physics-based relation correlating digital fringes with defocus.
• Implemented the digital defocus aberration interference (DAbI) method with a simple two-LED setup.

Main Results:

• DAbI quantifies defocus over a range of 443x depth-of-field for thin samples and 296x for thick specimens.
• Extended the imaging system's depth-of-field by 20-fold when integrated with complex-field imaging.
• Demonstrated versatile applications across brightfield, complex-field, refractive index, confocal, and fluorescence imaging.

Conclusions:

• DAbI provides an automatic, efficient, and generalizable solution for defocus detection.
• The method is compatible with various microscopy techniques, enhancing automation capabilities.
• DAbI is a promising advancement for high-throughput optical microscopy in biomedical research.