The hydrophilicity of the cell culture substrate was controlled by depositing it on the alumina surface through the laser-induced backward transfer (LIBT) method. Alumina particles were sized using laser energy density and deposited on the soda lime glass surface. The particle size and hydrophilicity of the alumina deposition surface were evaluated by measuring the surface roughness, contact angle, and light diffusivity. As the particle size increased, the effect of alumina became stronger, and the deposited surface had relatively higher roughness, stronger hydrophilicity, and higher light diffusivity. The stronger the alumina effect, the lower the growth of Staphylococcus aureus on the deposited surface. In this study, it was confirmed that selective bacterial growth and culture could be controlled by adjusting the strength of the alumina coating using the LIBT process.

The adhesive bonding technology of carbon fiber reinforced plastics (CFRP) and aluminum alloys, is one of the lightweight joining technologies for automobiles. The strength and properties of the bonded joint, depend on the surface of the bonded part that the adhesive touches. Thus, proper surface treatment is one of the most important steps in the bonding process. The laser surface treatment of carbon fiber composites is a new form of green and environmental surface treatment technology, which can effectively clean coatings and pollutants on the surface of materials. It is also possible to improve the bonding shear strength, by changing the microstructure and roughness of the material surface through laser micro texture processing, to form a mechanically interlocked structure. In this study, a pulsed laser was used to treat the surface of CFRP. By changing the scanning line spacing during laser micro texturing, the effect of laser micro texturing on the surface morphology of CFRP and the strength of aluminum alloy bonded joints was investigated. Results show that in the laser micro texturing process, when the scanning line spacing was 0.3 mm, the maximum tensile shear strength was 14.5 MPa, approximately 200% higher than that without laser treatment.

Modeling and analysis using a ray tracing method for internal defects were described. Reflection and refraction of rays on the interface of defects were modeled using the Harvey model and the Lambertian model. The diffraction on the interface of defects affected the incoming signals and it could evaluate any defects in the matter and its signal would be analyzed with the ray tracing simulation. The simulation results were compared with actual detecting signals and the ray tracing model was shown in good agreement with experimental data. This method has a possibility to be used as wave propagation modeling in non-destructive testing.

In this work, effects of plasma on different hardness of welding steel using laser-induced breakdown spectroscopy were investigated. The ratios of ionic to atomic spectrum peaks were related to its material hardness. The major spectrum peak (Fe) and minor spectrum peak (Mn) were considered as monitoring elements. The stronger repulse plasma was generated, the harder material it was. The ratios of ionic to atomic spectrum peaks increased with respect to the material hardness as well. The correlation of minor spectrum peaks was stronger than that of major spectrum peaks. However, the major spectrum peaks indicated a similar trend, which could be used to estimate the hardness, too. Based on this result, the method could be used as a noncontact remote measurement of material properties.

In this work, modeling and analysis of thermal effects laser drilling under water for ceramics were presented. Laser is a unique tool for machining ceramics due to the characteristic of non-contact material removal. However, ablation by a laser often induces a thermal effect on the material and an increased heat-affected-zone or deposition of debris can be observed on the machined parts. The underwater surrounding improved a heat transfer rate to cooling down the machined part and could prevent any deposition of debris near the machined surfaces and edges. The heat modeling was applied to obtain the temperature distributions as well as temperature gradients between the material and surroundings. The cooling effect of the underwater laser drilling was improved and a more stable temperature distribution was calculated. The actual laser drilling results of ceramic laser drilling were presented to verify the effects of underwater laser drilling.

Polymer micro-fluidic devices were fabricated with laser processes. A UV laser and a femto laser were used to machine polymer micro-fluidic structures directly. This laser direct machining process suits the need of rapid prototyping, as in many applications changes from the original design are often required. As examples, two polymer micro-systems were developed: a micro-check valve and a micro diffuser pump. The micro fluidic devices can be applied for many applications such as clinical diagnostics and drug delivery. Advantages and disadvantages using polymers as a material for micro-fluidic applications are discussed.