Search

In order to obtain the high-quality small holes and overcome the shortcomings of single pulse laser drilling,a new multi-pulse laser wave is introduced.Using the new manner,the hole of which the diameter is less than 1 mm,is obtained in 1mm-thick steel.Depending on the basic of theoretical analysis of multi-pulse drilling,the multi-pulse drilling can reduce the generation of melt interest and plasma,and the requirement of high energy for laser drilling.And it can also obtain the higher quality of drilling than the single laser drilling.In addition,the option of pulse width and pulse spacing is important for maching quality of laser drilling.It should choose shorter laser pulse width,when machine the high-quatity hole.Through the comparison and analysis of drilling results which are generated by waveforms of single pulse laser and multi-pulse laser,it is known that the quality of drilling results generated by waveform of three-pulse laser is superior to those of single pulse laser.And it is found that the average energy of effective pulse is 350 mJ,and the optimum pulse width and the best pulse interval are both 100 μs.

A sensor solution for weak vibration based on Fiber Bragg Grating Fabry-Perot(F-P) cavity is designed and experimentally demonstrated,in which a laser with single-frequency is used as the light source.The F-P cavity is affixed to the cantilever structure of even distribution of strain along the axis and the pair of fiber Bragg gratings as the cavity reflectors is placed freely.The vibration spreading to fiber grating F-P cavity through the cantilever beam vibration,causes changes in cavity length,thus changing the reflective light intensity of fiber grating F-P cavity.Theoretical analysis indicates that,the amplitudes and frequencies of vibration can be measured by demodulating the peaks and frequencies of the signal.The experimental results of measuring artificial vibration simulated with PZT agree with the theory well.This sensor has high measuring accuracy and can be used for detecting weak vibration.