SNR enhanced high-speed two-photon microscopy using a pulse picker and time gating detection.

Area of Science:

• Biomedical Imaging
• Microscopy Techniques
• Optical Engineering

Background:

• Two-photon microscopy (TPM) offers deep tissue penetration and optical sectioning for biomedical imaging.
• Label-free autofluorescence imaging in TPM is advantageous but suffers from low signal-to-noise ratio (SNR) due to weak fluorescence intensity.
• Low SNR in TPM presents practical challenges for detailed biological sample analysis.

Purpose of the Study:

• To enhance the signal-to-noise ratio (SNR) in label-free autofluorescence two-photon microscopy (TPM).
• To achieve high-speed imaging capabilities without compromising image quality or increasing photobleaching.
• To present a simple yet effective method for improving TPM performance in biological imaging.

Main Methods:

• Utilized a pulse picker with a femtosecond pulsed laser to decrease the repetition rate, thereby increasing pulse peak power.
• Employed time-gating detection methods to reduce background noise in the acquired two-photon images.
• Applied the developed TPM system to image arterial and liver tissues.

Main Results:

• Achieved significantly higher SNR in autofluorescence images of arterial and liver tissues.
• Obtained images with the same SNR over 19 times faster compared to conventional TPM, using the same average illumination power.
• Demonstrated that high-speed imaging with low total illumination energy mitigates photobleaching effectively.

Conclusions:

• The developed TPM system using a pulse picker and time-gating enhances SNR and imaging speed for label-free autofluorescence.
• This approach provides a practical solution for overcoming SNR limitations in TPM and other nonlinear microscopy techniques.
• The method offers a pathway for high-speed, high-quality biological imaging with manageable photobleaching.