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Diffraction Effects

When light passes through a small aperture, i.e. an aperture whose size if comparable to the wavelength of light, the wave nature of light causes interference effects that result in perceivable image quality loss. Images become more blurred due to the increasing support of the resulting point spread function of the optical system. An immediate consequence is that we cannot indefinitely gain depth of focus by reducing the aperture of the optical system as Equation TM:2.22 would suggest.

The following code snippet simulates the effect of diffraction with data corresponding to a high resolution digital compact camera, assuming a default wavelength of 29#29m: diffraction is modeled by convolution with an appropriate kernel
30#30

Figure 2.3: Diffraction results in significant contrast loss at commonly encountered operating conditions.
[width=8cm]figures/diffractionKernelF16.jpg [width=8cm]figures/diffractionKernelF163x.jpg
[width=16cm]figures/diffractionDetail.jpg



Roberto Brunelli 2008-11-25