A LabVIEW-based Autofocus Control System Design For Femtosecond Laser Micro-nano Fabrication Processing

With the wide application of laser processing technology in the manufacturing industry, the requirement for accuracy and efficiency of the micro machining is also getting higher and higher. Femtosecond laser processing technology, with true three-dimensional super-resolution, small thermal effect, wide range of materials processing and other unique advantages, has become a frontier field in technology processing. In order to achieve high quality, high speed and high precision micro-nano fabrication, this thesis improves original femtosecond laser processing system, increases the automatic focusing optical path, parallel processing, and uses the Lab VIEW software to write the control program of the system. This subject comes from the key project of National Natural Science Fund (51275502), and the main research contents are as follows:Confocal microscope technology is introduced to processing system; the femtosecond laser processing automatic focusing optical path will be designed; the imaging resolution of a confocal microscopy system to build will be analyzed; the 3D simulation of diffusion function curve method, the laser energy threshold automatic focusing accuracy is 0.05μm.The introduction of spatial light modulation technology to the processing system will make the system a set of parallel holographic processing system. According to the target light field, the thesis designs the corresponding calculate hologram pattern, and load it into the implementation of flexible modulation of femtosecond laser beam spatial light modulator, which can be obtained with a higher resolution pattern processing results.At last, the control program of the improved system was programmed by using the graphical software LabVIEW. According to the light field distribution of the target and design the G-S algorithm, apply MATLAB software to generate the machining process of computer generated hologram; through the control of confocal microscopy, optical shutter switch and three-dimensional scanning stage, the optical path of automatic focus will be completed; computer generated hologram using LabVIEW calling, loaded to spatial light modulator, it can achieve pattern processing; changing the wavelength of incident laser, controlling of the three-dimensional scanning stage to search the region of processing, and using photomultiplier tube of the confocal microscopy system, the internal information of the sample can be read out.Through the improved processing system, the automatic focusing of femtosecond laser, holographic parallel processing can be realized. And LabVIEW can be used to realize the effective integration of all aspects of the process of femtosecond laser processing and thus can be applied to micro and nano manufacturing field, providing an effective method for the rapid development of laser processing technology with high efficiency and high precision.