ABSTRACT
The use of computer generated holograms together with spatial light modulator (SLM) enable highly parallel laser micromachining. Usually SLM is used for splitting the original laser beam to desired number of beams with equal intensity. However, this technique also enables that the intensity of every beam can be controlled individually. Example of the hologram designing procedure for separation of the original beam to 400 beams with individually controlled intensity is presented. The proposed technique is demonstrated by femtosecond laser ablation of grayscale pictures so that grey scale of the pixel is addressed with corresponding beam intensity in the ablated picture.
ABSTRACT
The purpose of the present study is to explore topographical patterns produced with femtosecond laser pulses as a means of controlling the behaviour of living human cells (U2OS) on stainless steel surfaces and on negative plastic imprints (polycarbonate). The results show that the patterns on both types of material strongly affect cell behaviour and are particularly powerful in controlling cell spreading/elongation, localization and orientation. Analysis by fluorescence and scanning electron microscopy shows that on periodic 1D grating structures, cells and cell nuclei are highly elongated and aligned, whereas on periodic 2D grid structures, cell spreading and shape is affected. The results also show that the density and morphology of the cells can be affected. This was observed particularly on pseudo-periodic, coral-like structures which clearly inhibited cell growth. The results suggest that these patterns could be used in a variety of applications among the fields of clinical research and implant design, as well as in diagnosis and in cell and drug research. Furthermore, this article highlights the noteworthy aspects and the unique strengths of the technique and proposes directions for further research.
Subject(s)
Cell Separation/methods , Lasers , Molecular Imprinting/methods , Osteosarcoma/pathology , Osteosarcoma/physiopathology , Polycarboxylate Cement/chemistry , Stainless Steel/chemistry , Cell Count , Cell Line, Tumor , Cell Proliferation , Cell Size , Cells, Cultured , Humans , Materials Testing , Polycarboxylate Cement/radiation effects , Stainless Steel/radiation effects , Surface PropertiesABSTRACT
A high refractive index Te-enriched bulk chalcogenide glass Ge(20)As(20)Se(14)Te(46) (n approximately 3.3) has been patterned by ablation using four- and two-beam interference femto-second laser setups operating at 800 nm. The regular arrays of 0.8 mum diameter and more than 0.8 mum depth holes and/or grooves of typical size of 1x1 mm(2) have been written on the surface of the glass in a time-scale of 1 second with 50 femtosecond pulses. The high photosensitivity of this narrow-gap semiconductor glass to the femtosecond irradiation is ascribed to a free electron absorption typical of metals, which is caused by laser-induced heating of the glass.
