10-信息光学9.pdfVIP

#9 Frequency Analysis of Optical Image Systems （Chapter 6） Generalized treatment of imaging systems An imaging system is said to be diffraction- limited ? Thus the terminal property of a diffraction-limited imaging system is that a diverging spherical wave incident on the entrance pupil is converted by the system into a converging spherical wave at the exit pupil. ? For any real imaging system, this property will be satisfied, at best, over only finite for which this property holds, then the system may be regarded as being diffraction-limited. Effects of diffraction on the image ξ η ∞ ξ η U (u,v) = h(u,v; , )U ( , )dξdη i ∫∫ o ?∞ ξ η ξ ∞ ~ ~ η ~ U (u,v) = h(u ? ,v ? ~)U ( , ~)dξdη~ i ∫∫ g ?∞ ξ η ξ ∞ ~ ~ η ~ U (u,v) = h(u ? ,v ? ~)U ( , ~)dξdη~ i ∫∫ g ?∞ λ A ∞ π2 h(u,v) = ∫∫P(x, y)exp[? j (ux + vy)]dxdy zi ?∞ λzi P118 ? Incoherent illumination ? Coherent illumination 相干照明: 非相干照明: x x 0 i x0 xi A A B B Black B’ Black Box B’ Box y y 0 i A’ y0 yi A’ A, B两点光振动相干, 则引起的以A’, A.B 两点在像面上某点引起的复振幅没 B’为中心的两个分布也相干. 应将其干 有确定的位相关系。观察到的强度是多 涉图样求出后,再作模方求强度。 个像点强度的叠加，即非相干叠加。 Coherent illumination ? Thus a coherent imaging system is linear in complex amplitude. ξ η ξ 2 ∞ ~ ~ η ~ I (u,v) = h(u ? ,v ? ~)U ( , ~)dξdη~