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Ultrafast Pulsed Laser (Pulse Width from tens femtosecond i.e. 10−15 second to picoseconds i.e. 10−12 second) is a mature Laser technology which developed very well in recent years, it’s multiple applications are not only in industry but also academia. In academy, the applications include ultrafast phenomena, multi-photon microscopy, photochemistry and so on. In industry, it was applied in producing and processing on high precision components. This research utilizes the characteristic of ultrafast pulse laser and investigates the application of far-field optical super-resolution microscopy and the research of myocyte cells stimulation.

First we utilize the ultrafast pulse laser as our far-field super-resolution light source. Super-resolution microscopy is the foreground of the microscopy in recent 10~20 years. Because of the conventional optical microscopy are limited by diffraction limit, it can not resolve organelle structure and molecule interaction inside the cell , these properties are usually happened under tens to a few nanometer scale, however the diffraction limit is about 200 nm. The far-field optical super-resolution we developed is called STED (Stimulated Emission Depletion) which first innovated by Dr. Stefan W. Hell in 1994, who is now doing research in Max Plank Institute. The principle is using the “stimulated emission”, as we utilize another beam to make the outer area of fluorescence molecule to be stimulated emission, then the effective emitting area become smaller, so as to break the spatial diffraction limit, it can reach tens nanometer spatial resolution.

Secondly, we utilize ultrafast laser to generate stress wave to affect several living cells, and study the effect after the mechanical stress. When an amplify femtosecond pulsed laser focused in fluid , high intensity energy induce ablation phenomenon and create transient shockwave and bubbles simultaneously, this micron range stress wave push and shake the cells. We estimate the cell growth rate by counting the cells numbers to see if the cells stimulated by the mechanical stress or not.


Experimental setup 


The poster shows the difference resolution between (a) FLIM and (b) STED-FLIM.

Now our lab had achieved ~100 nm resolution.