development-noninvasive-laser-assisted-experimental-model-corneal

Development of a Noninvasive, Laser-Assisted Experimental Model of Corneal Endothelial Cell Loss

Nd:YAG lasers have been used to perform noninvasive intraocular surgery, such as capsulotomy for several decades now. The incisive effect relies on the ...

University of Lübeck

We developed a modified Hoffman contrast technique with a 12 ns pulsed incoherent extended white-light source that enables an easily interpretable visualization of ablation plumes with high resolution, a large dynamic range, and color information. By comparison, a conventional dark-field setup with a slitlike laser light source provides large sensitivity but a small dynamic range, and it is difficult to interpret the filtered images.

Sensitive high-resolution white-light Schlieren technique with a large dynamic range for the investigation of ablation dynamics.

We determined the bubble radius R_(max) for femtosecond optical breakdown in water at 347, 520, and 1040 nm with an unprecedented accuracy (+/-10 nm). At threshold, R_(max) was smaller than the diffraction-limited focus radius and ranged from 190 nm to 320 nm. The increase of R_(max) with laser energy E_(L) is slowest at 347 nm, providing optimum control of cell surgery. Experimental results agree with a model of bubble formation in heated and thermoelastically stretched liquids. Theory predicts a threshold temperature T_(th) approximately equal to 168 degrees C. For T>300 degrees C, a phase explosion sets in, and R_(max) increases rapidly with E_(L).

Article	Year
Sensitive high-resolution white-light Schlieren technique with a large dynamic range for the investigation of ablation dynamics. Optics letters\| PubMed ID: 16729079	2006
Femtosecond-laser-induced nanocavitation in water: implications for optical breakdown threshold and cell surgery. Physical review letters\| PubMed ID: 18233040	2008

Sebastian Freidank

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