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Low-cost Custom Fabrication and Mode-locked Operation of an All-normal-dispersion Femtosecond Fiber Laser for Multiphoton Microscopy
Published on: November 22, 2019
Evaluation of compact pulsed lasers for two-photon microscopy using a simple method for measuring two-photon
Samir Saidi1, Matthew Shtrahman2
1University of California, San Diego, Shu Chien-Gene Lay Department of Bioengineering, La Jolla, California, United States.
Significance:
Two-photon (2p) microscopy has historically relied on titanium sapphire pulsed lasers that are expensive and have a large footprint. Recently, several manufacturers have developed less expensive compact pulsed lasers optimized for 2p excitation of green fluorophores. However, quantitative evaluation of their quality is lacking.
Aim:
We describe a simple approach to systematically evaluate 2p excitation efficiency, an empiric measure of the quality of a pulsed laser and its ability to elicit 2p induced fluorescence.
Approach:
By measuring pulse width, repetition rate, and fluorescence output, we calculated a measure of 2p excitation efficiency , which we compared for four commercially available compact pulsed lasers in the 920 to 930 nm wavelength range.
Results:
2p excitation efficiency varied substantially among tested lasers. The Coherent Axon exhibited the best 2p excitation efficiency (), exceeding that of a titanium sapphire reference laser (defined to have efficiency = 1). However, its measured fluorescence was modest due to its long pulse width. Of the compact lasers, the Toptica Femtofiber Ultra exhibited the best combination of measured fluorescence () and 2p excitation efficiency ().
Conclusions:
We describe a simple method that both laser developers and end users can use to benchmark the 2p excitation efficiency of lasers used for 2p microscopy.
