Preliminary Research On Theory And Experiment Of The Open-loop Light Force Acceleration Sensing Based On The Dual-beam Optical Trap

Inertial navigation is an autonomous navigation method,which can accomplish navigation tasks independently without any external information aupport.It is widely adopted for military and commercial applications.Accelerometers and gyroscopes are the key components of the inertial navigation.On the basis of analyzing the advantages and disadvantages of traditional accelerometers,preliminary research on theory and Experiment of the light force acceleration sensing system based on the dual-beam fiber-optical trap were carried out.The development history of inertial navigation technology is briefly reviewed,the principles of different kinds of accelerometer were introduced,their advantages and disadvantages were compared.The principle advantages and frontier progress of light force acceleration sensing technology were analyzed emphatically,and the development potential of high precision and miniaturization was pointed out.The basic principle optical trap was introduced,and several theoretical models for light forces were summarized.Some calibration methods of the optical trap stiffness were introduced.The structure of the acceleration sensing system was introduced in detail.The bandwidth and resolution of the accelerometer are theorically analyzed.The error sources in the light force accelerometer were analyzed by using noise power spectrum.The influence of the radius,density and the stiffness of optical trap on the accuracy of acceleration measurement were analyzed and optimized.To solve the problem of the microsphere loading of the the optical trap in liquid,a kind of self-loading on-chip dual-beam fiber-optic trap proposed and tested.The launch of the microsphere in air based on vibration method was designed.The composition and influencing factors of adhesion force between microspheres and the supporting plane were analyzed.The influence of the launching velocity on the trapping was studied.The microspheres were succefully launched and captured based on the dual-beam fiber-optic trap and the vibration method.The common methods of position detection were summarized,and their advantages and disadvantages were both discussed.Some common algorithms of displacement measurement based on image processing technology were introduced.And based on the centroid tracking algorithms,we compiled the software of displacement measurement of the microparticle in the optical trap.The displacement measurement system based on image processing was also built,and the position resolution of 10 nm magnitude was obtained experimentally.The theory of the back-focal-plane displacement measurement of the microparticle was analyzed.It's the first time to apply the back-focal-plane method using the side-scattered light in dual-beam fiber-optic traps.And the voltage-displacement conversion factor of the detector is calibrated by the orbital rotation with transverse offset.A measured displacement noise of (?) was obtained.The influence of microsphere radius,fiber spacing and numerical aperture of the objective on position detection was systematically analyzed by utilizing ray optics.The position measurement system was designed by using Doppler velocimetry and phase generated carrier approach,in which the fiber end was coated to improve the contrast ratio of intereference signals.A novel displacement measurement method using the coupling power of the forward-scattered light of the microparticle was proposed,and the principle and the way to improve the resolution were analyzed.We built a light force acceleration sensing system based on the on-chip dual-beam fiber-optic trap.Using the quartz flexible accelerometer as a reference,the performance was tested the experiment.Experiments showed that the displacement of the microparticle was proportional to the input acceleration.The maxium scale factor of the accelerometer reached 45?m/g,and the bias stability was 2.3 mg.We have edited the scale factor calculation software by the graphical user interface(GUI)in Matlab.The influence of microsphere radius and the refractice index on the scale factor was analyzed.After optimizing some parameters,the scaler factor increased to 247.82 ?m /g.