Research Grazing Incidence Mirror Parabolic Shaped Fringe Distortion Detection Based Method

At present, most researchers have mainly focused on the figuration principle andtechnology of X-ray parabolic mirror．However, its effective and high-precision shapedetection method is still at a groping stage. In this Paper, a simple and novel method foroptical surface measurement is presented. The basic of the method is to display acomputer-generated sinusoid gray fringe pattern on a computer monitor, the vertical andhorizontal changed phases can be calculated respectively, which links to a dual-imaged PCcard. The deformed orthogonal fringes reflected by the mirror under test are captured by aCCD camera, and to calculate the phase changes of the fringes by using four-framephase-shifting algorithm. Then Phase unwrapping for Wrapped phase—map are simulatedby using Goldstein Branch cut algorithms． And also we deduce a correspondingrelationship between the gradients of measured surface and the changed Phase throughimage-forming principle. Because the obtained gradient field is a discrete gradient, we canreconstruct the measured surface by numerical integration （Fourier transform integralmethod in this paper）,and complete the measurement of the parabolic mirror shape.In this paper, we conduct several simulations for the experiment. It is mainly dividedinto two parts. First, we implement and verify the four-frame phase-shifting, the phaseunwrapping and the key algorithm of shape reconstruction through the computer. Second,we simulate the whole experiment process, which is how to reconstruct shape through thedeformed stripe.What’s more, we set up an experimental measurement system and measurethe shape of grazing incidence parabolic mirror. And also we acquire vertical andhorizontal stripes, and then reconstruct shape. We verify the feasibility of measuringmethod and analyze the influence of various errors on the measurement accuracy.Compared with those traditional interferometries, this method has lots of advantages,such as low cost, simple structure, and high flexibility. Moreover, as the improvement ofCCD and display resolution, the measurement accuracy will be further improved. Therefore, the method has broad application prospects. The research of this paper willprovide theoretical basis and technology support for the further research on the shapemeasurement of X-ray parabolic mirror．...