Research On Optical System For Three-dimensional Profile Measurement Based On Confocal Principle

With the continuous development of precision machining technology,high-precision equipment has become increased in industries such as optoelectronics,materials,information,and biomedicine.Meanwhile,all kinds of precision and tiny components are widely used and new requirements are put forward for the detection technology of the surface quality of components,which promote the development of three-dimensional profile measuring technology.Chromatic confocal three-dimensional profile measuring technology which has emerged in recent years is a non-contact surface measurement method based on wavelength and height modulation.It has the advantage of high measurement accuracy,high speed,online measurement of components and wide range of applications.This article is based on the principle of chromatic confocal three-dimensional surface profile measurement,using the theoretical analysis and simulation methods to research the key factors affecting the performance of the chromatic confocal measuring system.1.Investigate the development of chromatic confocal technology at home and abroad.By analyzing the principle of chromatic confocal measurement technology and the performance indicators of the system,determine the constitution and overall design scheme of the chromatic confocal 3D profile measuring system.2.The ZEMAX optical design software is used to design and stimulate the core component of the measurement system: dispersive objective,and the image quality of the dispersive objective is analyzed and evaluated.The axial chromatic aberration of the dispersive objective is 120um in 450-700um,and there is a good linear relationship between the axial chromatic aberration and wavelength,with the linear regression determination coefficient R~2= 0.9996.The paraxial image surface of each monochromatic light is close to the Airy disk,and the dispersive objective has nearly reached the diffraction limit.3.Analyze the various systems that make up the spectrometer and use ZEMAX to design and simulate a Crossed-asymmetric Czerny-Turner spectrometer,whose resolution reaches 0.2 um.4.Analyze the detection accuracy of the chromatic confocal three-dimensional profile measuring system,then take the effect of machining and mounting errors into considered in the actual manufacturing process and perform the tolerance analysis,thus the system measuring accuracy reaches 0.1 um.This research shows that chromatic confocal three-dimensional profile measurement is a highly efficient on-line measuring method for surface morphology,which has universal applicability to surface measurement of optical components,and has a great deal of space to play in the surface detection of medium and high-precision components.