Study Of Center Of Curvature And Conic Constant For The Measurement Of Primary Mirror Of Telescope

The telescope mirror shape is fully defined by two parameters R(radial of curvature) and K(conic constant) during its manufacture. An error in R shifts the focal position, but an error in K causes spherical aberration that degrades the telescope performance. Along with the development of the modern optical technology, higher quality of telescope image is required, so to study the accurate measurement of the telescope parameters is very important and significant. This paper mainly study radial of curvature and conic constant from two aspects, calculate the radial of annule shadow and pick up zero-phase of the interfergram. Its main contents are as follows:1.Intrduced the basic theory of the wire shadow test, deduced the formula of the parameters of the primary mirror. In order to solve the pathosis problem by the tiny measurement error of equations, the singular value decomposition( SVD) method is used. From the experiment of 1.8-m primary mirror, simulation results have verified the efficiency of the method. When measure the radius of the annule shadow, the average of the inward and outward radius of the annule shadow is used to replaced the theory value, simulation results shown this method is right. Then explained the reason of the error of this method.2.Pick up the pix radius of the annule shadow to solve the parameters of the telescope by establish the data communication between zemax and matlab, from the simulation results, we analysis the source of the error. In order to improve the precise of the calculation results, the resolution ratio of the pix is increased, simulation results shown the correction of this method. Describe the theory of a new method to test the radial of curvature of the asphere mirror, from the experiment of the 140 mm paraboloid mirror, we analysis the error and prove the correction of this method.3.In order to solve the disadvantage of picking up pix of annule shadow, zero-phase of the interfergram is picked up, calculate the real radius of the mirror from the pix radius, then to solve the R and K of the mirror. From the simulation, we can see the result is more accurate than the method of calculating the average of annule shadow.