Research And Application Of The Common-path Radial Shearing Interferometry

The common-path radial shearing interferometer is an effective interferometry to test the wavefront, in this method the measured wavefront will be divided into two wavefronts which have different amplificatory or contractible multiple by a interferometer, the two wavefronts make radial shearing interference in their overlap area. Compared with Twyman-Green interferometer and Fizeau interferometer which are belonged to classic two paths interferometry, the radial shearing interferometry needn't setting special reference beam of light, it has high precision, and it is not sensitive to the vibration of machine and the disturbance of the environment.In this paper, it is suggested that a new radial shearing interferometer that based on double Fresnel zone plates to test temperature field which is formed by two parallel hot clubbed copper, the shearing interference is realized by the two different focus zone plates,the 3-D temperature field is reconstructed by using optical computerized tomography (OCT). The algebra usually adopted cannot be solved the problem of reconstruction precision very well for incomplete test data in the process of reconstruction. So the property matrix including the prior knowledge is introduced, an unfixed ultra-relaxation coefficient is adopted in the algorithm to reconstruct the 3-D temperature field.The calculating results indicate that the 3-D temperature field can be reconstructed more accurately by the algorithm with property matrix and unfixed ultra-relaxation coefficient.In this paper, the measuring wavefront of aspheric lens is another application of this interferometry. The interference pattern involved the phase distribution of the measured wavefront is got by two zone plates too. The phase difference of the two wavefronts will be calculated by using SCPM from the interference pattern, and the phase of original wavefront will be got by adding the phase difference along the radial direct in the polar coordinates. This method has the advantages of the high precise and measurement on-line, not only that, but it don't destroy the shape of the lens.The two experiments indicate that the optical system of radial shearing interferometry is diversity, and this interferometry can measure various objects, and it have the advantage of high precision and we can chose the precision according to different tested objects.