Acquisition And Auto-interpretation Of White-light Interference Peak Signal

Data acquisition and processing is a crucial part in many detecting and measuring system, including white-light interference system.In the traditional form,data acquisition is implemented by PC and data acquisition board,and data processing is realized by some designed software.However,this method has many disadvantages,such as complex design and enormous amount of calculation.It is also too inflexible to apply in field measurement.With the development of DSP technique,nowadays,DSP has become one of the most efficient means of information acquisition and processing.As one kind of specialized data processing microprocessor,DSP also provides a novel approach for optical information processing.In this paper,a novel technique combined by DSP and scanning optic-fiber white-light interference was proposed.The characteristics of the method are that DSP takes the place of PC and data acquisition board in traditional scanning white light interference system, the control of experiment process and the high speed acquisition of interference signal can be realized through transferring the procedure stored in DSP.Meanwhile,considering the theory of two beam interference with arbitrary spectra,a novel method for interpretation of the peak of the white-light interference envelop,based on the DSP technique,was proposed.This method could solve the problem resulted from the dissymmetrical envelop of interferograms.Based on this method,an automatic SWLI system using TMS320F2812 as a core was designed.To verify the performance of this system,an experiment of measuring the thickness of transparent oil film on water was followed.Compared to the ideal value,the measurement value has a bias of 1.7%with a difference no more than±1.3%induced by continuous measuring.Results show that this system runs stably and has a higher efficiency and resolution than the traditional one which is generally based on PC.