Compact multi-band fluorescent microscope with an electrically tunable lens for autofocusing

Area of Science:

• Microscopy and Imaging Technologies
• Biophotonics
• Cell Biology

Background:

• Autofocusing corrects focus drift in time-lapse microscopy.
• Traditional distance detection methods struggle with low signal contrast at interfaces like water/glass.
• This limits speed and introduces motion artifacts in live-cell imaging.

Purpose of the Study:

• To develop a compact, high-speed autofocusing microscope for real-time live-specimen imaging.
• To overcome limitations of conventional autofocusing techniques in challenging imaging conditions.
• To enable precise and rapid microscopic observations within incubators.

Main Methods:

• Designed a compact multi-band fluorescent microscope incorporating an electrically tunable lens (ETL).
• Implemented a modified equidistant scanning and curve fitting algorithm for robust autofocusing.
• Tested the system's autofocusing speed and reproducibility.

Main Results:

• Achieved autofocusing times as low as 170 ms.
• Demonstrated high reproducibility of over 97% for the autofocusing technique.
• Developed a portable imaging head (12 cm x 12 cm x 6 cm) suitable for incubator integration.

Conclusions:

• The developed ETL-based microscope offers rapid and reliable autofocusing for time-lapse imaging.
• The novel algorithm enhances robustness against external disturbances and refractive index mismatches.
• This portable system facilitates real-time imaging of living specimens inside incubators, advancing cell biology research.