Research And Design For Fractional CO₂ Laser Treatment Instrument Control System

The appearance of selective photothermolysis laid the theory basis for using laser in cosmetic field. Subsequently the theory got further perfection and supplement during the process of clinical treatment such as fractional photothermolysis theory. Fractional photothermolysis theory bases on minimally invasive rehabilitation mechanism of human body, which induced fractional laser treatment technology that is recently the most popular skin cosmetic technology in America. The technology is a minimally invasive treatment which lies between invasive and minimally non-invasive methods. It is a safe method, has obvious effect and can treat any part of human body.With the development of laser technology, kinds of laser sources can be suitable for fractional treatment including many ablative and non-ablative ones. Clinical reports prove that non-ablative laser treatment has high chance for pigmentation and slow effect emergency. The skin experts began to prefer CO2 laser as treatment laser source, which has been proved to get quicker effect than non-ablative laser. It cannot cause hyper-pigmentation but can remove epidermis stain. Thus, the thesis takes CO2 laser as the light source to design corresponding fractional laser device.Besides necessary functions, the medical devices have high requirements for safety and reliability which mostly depends on control system, so the thesis points lie in the control system of fractional CO2 laser device. Firstly, the thesis gives brief introduction for interaction between laser and skin, laser treatment theory and the characteristic and development of carbon dioxide laser, and then details the design philosophy for control system, analyzes key points and gives corresponding solutions. The main contents are listed as the following:(1) With the analysis of system functions, adopt modularization-design principle to design MCU-based hardware platform and software function for fractional laser device, and analyze hardware anti-jamming solutions.(2) Implement laser output with many pulse modes and exactly control laser energy and pulse duration. To assure laser safety, design and adopt a patent called"A method for preventing D/A out of control"which owns proprietary intellectual property rights.(3) Implement human-machine interface through touch screen display, PC and printer.(4) Analyze and design required fractional graphic boundary scanning and shape filling algorithm.