Snapshot Chromatic Confocal Three-dimensional Measuring Instrument With Adjustable Performance Parameters

In recent years,optic manufacturing,mechani manufacturing,chip packaging and other industries have more and more demands for 3D surface topography detection.Most of the commonly used detection methods require mechanical scanning,which limits the detection efficiency.In order to further improve the detection speed and accuracy,the snapshot chromatic confocal 3D measurement technology is studied,and the 3D topography information in a certain area can be obtained quickly without scanning.Firstly,the research background is described.The classification of 3D morphology detection technologies and the working principle of main optical detection methods are introduced.After that,the snapshot chromatic confocal measurement technology is proposed,and the working principle of the components of the system is introduced.The relationship between main performance indicators and structure parameters of optical system are analyzed to provide theoretical guidance for the system design.Then,the light source,axial dispersion and spectral detection modules of the measuring system are designed and analyzed.In the light source module,the white LED with high power,small volume and relatively flat spectrum is selected as the light source,and the uniformity of the integrating sphere is analyzed.In the spectral dispersion module,the wide-field axial dispersion lens is divided into two parts symmetric about the front and back of the stop.The design difficulty is reduced by using half group design method.The performance parameters of the axial dispersion lens can be adjusted by replacing the group of lenses.The design results of the dispersion lens with two kinds of performance parameters are given,and the tolerance analysis and thermal difference analysis are completed.In order to reduce space between adjacent pinholes,there is an angle between the pinhole array direction and the dispersion direction.In the spectral detection module,a spectral imaging detection system based on double Amici prisms is designed to reduce the nonlinear dispersion of the prisms and make the optical path coaxial structure.The optical and mechanical design of the optical system is completed,and the stray light analysis is carried out by the white-black spot method,which is close to the theoretical value.Finally,the prototype is assembled and tested.The calibration experiment,spot diameter test,repeatability test and axial resolution test are carried out.The pixel position and displacement are calibrated directly,which reduces the workload and calibration error.The principle of laser autocollimation is used to ensure that the optical axis of the axial dispersive lens is perpendicular to the surface of the measured object during calibration.The Gaussian fitting peak extraction algorithm is used to improve the axial resolution of the prototype.In conclusion,a snapshot chromatic confocal measurement system with adjustable parameters is designed and developed in this thesis,which adopts the transmission coaxial form and has a compact structure.Under the condition of keeping the illumination,the front set of dispersive lens and the spectral detection system unchanged,the different detection performance parameters can be realized by replacing the back set of dispersive lens.The validity of the measurement method and the design results is proved by the development of the prototype and the test experiment.