Multi-mode pump-probe microscopy with high resolution beyond diffraction limit

Takayoshi Kobayashi^1,2,3*

¹Advanced Ultrafast Laser Research Center and Brain Life Support Center, The University of Electro-Communications, 1-5-1 Chofugaoka, Chofu, Tokyo, 182-8585, Japan
²JST, CREST, 5 Sanbancho, Chiyoda-ku, Tokyo 102-0075, Japan
³Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan

* Presenter:Takayoshi Kobayashi, email:kobayashi@ils.uec.ac.jp

Atomic-resolution microscopy (e.g. electron diffraction, X-ray diffraction) often requires a vacuum condition and is not suitable for living cells. Super-resolution optical microscopy was developed recently e.g. STED [1]. This requires special donut mode light source setting. Most of laser microscope uses fluorescence and hence requires fluorescence labelling which may perturb a small target cells because ordinary biomaterials are nonfluorescent.

We have developed multimode super-resolution microscopy to study various bio and medical samples. Developed pump-probe multi-mode imaging has two modes; stimulated emission (stimulated emission imaging microscope, SEIM) mode and photothermal (photothermal microscope, PTM) mode.

Using then we could obtain 140 nm resolution and we can reach 70 nm with non-linear detection scheme [2]. We have imaged the samples of brain, kidney, and skin cancer of mice and muscle of a rat [3-5].

The advantages of our method are (1) compact, (2) applicable to nonfluorescent sample, (3) multi-color imaging available.

We further extended the PT microscope by using a super-continuum light source as the pump light for extension to multi-color microscope. The use of an acousto-optic tunable filter enabled us to freely select the wavelength of the SC light up to 8 wavelengths in the range from 450 nm to 550 nm and to modulate the pump light intensity. As a probe light, a relatively stable laser-diode is used.

References
[１] T. Grotjohann, I. Testa1, M. Leutenegger1, H. Bock, Ni. T. Urban1, F. Lavoie-Cardinal1,K. I.Willig, C. Eggeling. S. Jakobs and S. W. Hell1, Nature, 478, 204 (2011)
[2,3] J. Miyazaki, K. Kawasumi and T. Kobayashi, Rev. Sci. Instrum., 85, 093703, (2014), Opt. Lett., Vol.39, No.14, 4219-4222 (2014)
[4,5] J.-P. He, J. Miyazaki, N. Wang, H. Tsurui, and T. Kobayashi, Opt. Lett.Vol.40,No.7, 1141-1144(2014), Opt. Exp. Vol. 23,No.8, 9762-9771(2015)

Keywords: Multi-mode pump-probe microscopy, multimode super-resolution microscopy