Research On The Measurement Technology Of Optical Lens Group Decentration Based On Liquid Lens

In the process of developing the optical group,due to the limitation of processing technology and assembling precision,the optical axis of each lens in the optical group will be biased,which will destroy the coaxial condition of the optical group and lead to the degradation of the optical performance of the optical group.decentration is a key index used to measure the consistency of optical axis of optical lens or lens group.It is widely used in lens machining and lens assembly adjustment.It is necessary to measure and correct decentration accurately with the help of center bias measuring instrument.With the higher and higher requirements for the accuracy and efficiency of lens group sets,it is of great significance to improve the automation degree of measurement system and reduce the operation requirements while ensuring the accuracy of decentration measurement.The traditional decentration measurement scheme needs to replace the measuring lens according to the surface shape parameters of the lens to be measured,adjust the measuring height,and find and determine the position of the reflected light spot,which is inconvenient to operate and easy to misjudge.In this thesis,a bidirectional reflection decentration defocus measurement scheme based on liquid zoom lens is proposed.The liquid lens is used to achieve continuous zoom of the measurement system,which can actively adapt the surface shape of the lens to be measured according to the optical structure parameters of the lens group,thus improving the freedom of adjustment.After considering the structural parameters of the optical mirror group,the best position of the measuring device is determined.The decentration measurement of each lens surface in the same lens group can be realized without changing its height,which is convenient to operate and has a higher degree of automation.The bidirectional optical path structure can simultaneously measure the decentration of the upper and lower surfaces of the lens to be measured,which is conducive to improving the working efficiency of the system.Firstly,the decentration measurement methods are summarized,and the bidirectional reflection decentration measurement scheme based on liquid zoom lens is proposed.The mathematical model of the decentration measurement scheme is constructed,and the theoretical calculation and software simulation are carried out.The results show that the tilt resolution of the scheme is ±0.5" and the eccentricity resolution is ±0.1μm.With high measurement accuracy;Secondly,according to the working mechanism of the measuring scheme,the measuring optical path is designed,and the working mode of the measuring system is analyzed theoretically and verified.The analysis and verification results show that the measuring optical path is reasonable and can meet the measurement requirements.Finally,the design and construction of the decentration measuring instrument prototype were completed,and the decentration measurement and installation test of the optical lens group were carried out.The measurement results were compared with the commercial decentration measuring instrument.The accuracy and reliability of the decentration measuring instrument prototype were verified,and the error sources of the measuring system were analyzed according to the test situation.The corresponding improvement measures are put forward.The results show that this measurement scheme is suitable for measuring and adjusting the decentration of multi-lens optical group.It has light structure,convenient operation and high measurement accuracy,and has certain engineering application value.