Effect of side and central obstruction for circular aperture on image intensity of optical system using triangular object

Abstract EN

In this research, the effect of obstructed circular aperture from the sides by line or by hyperbola has been studied to the specific values of the obstruction (0.25, 0.5, 0.75) on the image of triangular object by studying triangular spread function of triangular object for ideal optical system or contains focus error (W20 = 0.5λ, 1λ) or spherical aberration (W40 = 1λ ) or astigmatism aberration (W22 = 1λ) with rotation angle (ϕ = 0), the results have been compared with the circular aperture and obstructed circular aperture centrally in same values of side obstruction.

The results showed that increasing the side obstruction in the ideal system leads to increase depth of focus of the image while the increasing ratio of central obstruction leads to increase the resolution power of the optical system, as for when there are focus error or aberrations in the optical system, the side obstruction is working to increase the intensity in the formed image and reduce the effect of aberrations on the distribution of intensity at plane of the image, while the central obstruction lead to distortion the formed image by the triangle.

The side obstruction gave good results for the distribution intensity of image and increase the side obstruction lead to increment image clarity, so the value of side obstruction (0.75) better than the other cases selected in the search, so that using the aperture obstructed by line better than using aperture obstructed by a hyperbola as given the preference in values of intensity of the formed image.