Annular subaperture stitching technique is a feasible method for testing rotationally symmetric aspheric mirror without any additional elements. Based on the testing principle

a subaperture layout model was established with geometry optics theory

and the numerical solving method was provided in detail. Taking a paraboloidal mirror with clear aperture of 700 mm

center obscuration of 160 mm

and vertex curvature radius of 3000 mm as a example

the paper analysized and explained the numerical results of model with the corresponding physical optics theory. The experimental results show that the model is better in predictability

and it will provide the theory basis for the practical measurement and also will make the measurement process more controllable

quantitative and repeatable.