Autofocusing technologies for whole slide imaging and automated microscopy

Area of Science:

• Digital Pathology
• Microscopy Imaging Systems
• Biomedical Optics

Background:

• Whole slide imaging (WSI) advances digital pathology, but tissue topography variability poses autofocusing challenges.
• Traditional focus map methods limit focus point acquisition and throughput in automated microscopy.
• Accurate and rapid autofocusing is essential for efficient WSI and diagnostic applications.

Purpose of the Study:

• To review traditional focus map approaches for autofocusing in WSI.
• To discuss various real-time autofocusing techniques for automated microscopy.
• To compare the merits and limitations of different autofocusing methods against traditional WSI systems.

Main Methods:

• Review of traditional focus map surveying for focal plane determination.
• Discussion of real-time autofocusing approaches: reflective triangulation, confocal pinhole detection, low-coherence interferometry, tilted sensor, dual sensor scanning, beam splitter array, phase detection, dual-LED illumination, and deep learning.
• Comparative analysis of technical concepts, advantages, and disadvantages of reviewed methods.

Main Results:

• Traditional focus map methods are throughput-limited.
• Real-time autofocusing decouples focusing from image acquisition for rapid scanning and continuous focus.
• Multiple real-time techniques offer potential improvements over traditional methods.

Conclusions:

• Real-time autofocusing is key to achieving high-throughput automated microscopy for WSI.
• The reviewed methods provide diverse strategies for enhancing focus accuracy and speed.
• This review offers insights for developing advanced, broadly usable microscopy imaging systems.