Research On Measuring Technology Of Curvature Radius With Internal Focus

As one of the important parameters of optical components,the radius of curvature plays an important role in the subsequent optical inspection and adjustment.At present,the general-purpose measuring instrument is a main development trend.This measuring instrument can measure various parameters of optical components.Therefore,this paper expands the function of the original internal focusing and centering instrument,so that it can also be used for centering at the same time.Ability to accurately measure the radius of curvature of optical components.Through the analysis of the principle and process of measuring the radius of curvature of the original internal focusing and centering instrument,it can be seen that the main reason affecting the accuracy during measurement is the error generated in the focusing process.Therefore,this paper mainly improves the measuring instrument according to the factors that cause the focusing error.An experimental platform was built,and the optical components were actually measured to verify their measurement accuracy.The main contents of this subject are as follows:Firstly,the method of measuring the radius of curvature of the internal focusing autocollimation is studied.For the internal focusing measuring instrument used in the measurement of this topic,the scale reading it uses is intermittent reading,and the measurement result can only be estimated.Therefore,the scale needs to be measured.The intermittent reading of the instrument is changed to a continuous reading,and the reading on the ruler is the working distance of the inner focusing optical system.The basic parameters of the instrument’s inner focusing optical system are theoretically calculated,simulated in Zemax,and communicated with the DDE of Matlab through Zemax.Function,the working distance data of the ruler is proposed,so that the original reading ruler data can be subdivided to the micron level.At the same time,according to the internal focusing optical system during its own focusing process,since the working distance changes in different ranges,the working distance is different.Perform segmentation and determine the radius of curvature measurement range for different working distances.Next,an optical imaging model is established,the relative error of different measurement ranges of the instrument for measuring the radius of curvature of the inner focus in the case of manual focus is analyzed;The hill-climbing algorithm realizes automatic focusing,and the relative error of different measurement ranges is calculated through theoretical calculation when the automatic focusing method is used for measurement.Finally,through the above theoretical analysis,the components needed in the experiment are selected,and the experimental platform is built to verify the theoretical results.The theoretical working distance and the actual working distance are verified,and the experimental results are consistent with the simulation results;and the accuracy and repeatability of the curvature radius instrument under the measurement range of different working distances are verified.The nominal value of the curvature radius is 41.2mm Measured with optical components of-57.1mm at different working distances,and the actual measurement error results are within the theoretical calculation error.Experiments show that this instrument can be used for general measurement of spherical curvature radius.