Papers by Author: Ming Fei Chen

Abstract: This study will be UV (355nm) laser processing system as a carrier. Using laser direct forming for CIGS solar cell technology P2 layer of stainless steel studied electrode insulated characteristic. To explore the impact of this process on the way to a stainless steel substrate P2 film sizes using its laser different frequency parameters. The experimental results indicated that the electrode pattern of the experiment was similar to that of the simulation result, and the laser process has good results in scribing processing. The analysis results confirm the effectiveness of the laser apparatus when applied to a CIGS solar cell P2 layer of stainless steel.

Abstract: Polymethylmethacrylate (PMMA) material has excellent characteristics, such as being light weight, low cost, ease of machining, and optical quality, which are useful in numerous applications such as backlit LCD display panels, lens optics, and other photoelectric fields. Laser machining of polymerization material results in a superior machining quality, high accuracy, high speed, and high reproducibility, produces a small variety of products, reduces mold costs, and enables the rapid manufacture of products based on complex graphics by processing different depths and widths of the 3D structure. This paper presents the fabrication of symmetrical array microstructures on PMMA material by using a UV laser system. The PMMA material dimensions and thickness were 20 x 20 mm and 1 mm, respectively. Regarding the machining quality, the laser pulse energy, pulse repetition frequency, and fill spacing were adjusted. For the experiments, a semiconductor laser source (635 nm/5 mW/TEM₀₀) and a beam profiler were used to measure the characteristics of a laser beam passing through the microstructures. The microstructure pitches and morphologies also affected the light uniformity. After laser machining, the surface morphology and the light transmittance were measured using a spectrophotometer.

Abstract: The aim of this study is to derive the governing equation of an electrostatically actuated micro system by use of the Hamilton principle, and then the natural frequencies of a micro fixed-fixed beam are derived as the solutions to a boundary value problem with prescribed boundary conditions through the differential transformation method (D.T.M.). The differential transformation employed is a transformed function based on the Taylor series that is effective in solving nonlinear problems with fast convergence. The numerical results of the calculated natural frequencies are compared with the analytical data and were found to be in good agreement. Hence, the differential transformation method is one of the most efficient methods of simulating the electrostatic behavior of a micro-structure system, and it has a great potential for use in the analysis of the micro fixed-fixed beam.

Abstract: This paper presents an approach to utilize high precision pulsed Nd:YAG laser to fabricate a rough array-pattern on a soda-lime glass plate by a laser-induced backside writing (LIBW) process, and a laser-induced plasma assisted ablation (LIPAA) technique. The current study investigates the effect of process parameters such as single-shot laser exposure time and number of passes on the material removal rate. After depositing 695 nm thick Teflon thin film on the glass plate, the surface of the laser micro-machined template becomes hydrophobic. The surface roughness, annular groove profile and surface micrograph were measured by an atomic force microscope, a profilometer, and a scanning electron microscope, respectively. A uniform liquid droplet by the sessile drop method is generated on the hydrophobic template. Droplet characteristics, such as contacted angle, size, and shape, are measured with a surface tension analyzer and microscope. This work also discusses the relationship between the formed droplets and the process recipe of the micro-machined template. The proposed approach can apply to future for uniform lens array formation.

Abstract: The scanning system which uses the non-linear focusing lens is usually accompanied by a major problem that is a non-constant scanning velocity of the spots in the projection plane. Moreover, the energy of the spots and the shape of the drilling holes would be affected. Hence, the focal lens of the scanning system usually uses the f-theta lens to solve this problem. This paper proposes a method utilizing the ZEMAX to analyze the commercial F-theta lens. The results indicate the F-theta lens can increase the quality of the drilling holes and amend the projection plane. In order to verify the analysis results, each diameter of an array holes drilled by the CO2 laser drilling machine would be measured. The experimental results can demonstrate that the percentage of the variation in the diameter of holes is close to the simulation results. Therefore, the method can effectively analyze the F-theta lens of the scanning systems.

Abstract: Laser patterning technology of indium tin oxide thin films has been studied in this research. ITO thin films, which usually coat on the glass and the plastic substrate, have been adopted in the flat panel displays (FPDs) and the plasma display planes. The conventional method of the ITO patterning usually uses the wet chemical etching processing. However, the wet etching processing is not adopted in the plastic materials because the chemical fluid usually damages the plastic substrate. The laser direct writing processing has been developed and replaces the wet etching processing. This investigation is interested in the laser patterning used the third-harmonic Nd:YAG laser (355 nm) to ablate the ITO films of glass substrate. The scanning electron microscope (SEM) measures the characterization of the ablated grooves used the different parameters, including the laser energy, the repetition rate and the feeding speed of the table. Finally, the effect parameters of laser ablating ITO film will be presented in this paper.

Abstract: This paper has partitioned the laser range-finder into two parts: one is the laser diode (LD) driver circuit and the other is the focusing lens. The LD’s surface temperature rise will affect the LD’s light-power simultaneously when an LD works in a steady current. For this reason, we designed a driver circuit to control the LD’s light power to be effective and so as to freely adjust the LD’s brightness. There are three parts in driver circuit: the regulated power circuits, the regulated current circuit, and the limited current circuit. This investigation used a power meter to measure the LD’s power which was relative to the surface temperature. Then the experimental results were compared with the PSpice simulation, and the differences between the result and the simulation were eventually analyzed. The limited current circuit is an important part in our systems because the LD is easily damaged when active current is unstable. Similarly, the surface temperature would be raised after the LD is working for a while which results in the circuit failure. If the LD has worked for a very long time, the heat generated in the circuit should be taken care of. Therefore, we added an automatic power control circuit (APC) into the LD driver circuit in order to reduce the impact of heat. The emitted distance of laser beam could be up to 10 meters with adjusted focusing lens. The laser spot was extended into an ellipse before focusing laser beams. Therefore, we had to put a focal lens to shape the the laser spot into a circular spot. During this experiment, the LD did not work directly without installing the heat sink. Otherwise, the high temperature would damage LD immediately.