Scalar paraxial Fresnel propagation
A monochromatic scalar field in a uniform medium propagates paraxially as E_z(x,y)≈e^(ikz)/(iλz)∫∫E₀(ξ,η)exp[ik((x−ξ)²+(y−η)²)/(2z)]dξdη, with k=2π/λ.
Key knowledge
A monochromatic scalar field in a uniform medium propagates paraxially as E_z(x,y)≈e^(ikz)/(iλz)∫∫E₀(ξ,η)exp[ik((x−ξ)²+(y−η)²)/(2z)]dξdη, with k=2π/λ. The quadratic phase retains near-field diffraction structure.
Values and equations
E_z(x,y)≈e^(ikz)/(iλz)∫∫E₀(ξ,η)e^[ik((x−ξ)²+(y−η)²)/(2z)]dξdη
- E_z,E₀
- Output/input complex field amplitude V m⁻¹
- x,y,ξ,η,z,λ
- Coordinates, propagation distance and medium wavelength m
- k
- Medium wavenumber m⁻¹
- i
- Imaginary unit
Conditions and scope
- Forward scalar homogeneous propagation with z>0, narrow propagation angles, slowly varying amplitude and negligible omitted quartic propagation phase over the relevant aperture/observation region.
- High-numerical-aperture, subwavelength apertures, evanescent fields and vector polarization effects need a fuller Maxwell treatment; paraxial does not imply far field.
Sources · 1
References
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Evidence and review
Optics 2.71: Recitation 3 (2014): Initial diffraction formulas: normalized point-source Fresnel kernel and aperture-field propagation integral; coordinates relabeled.
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Entry details
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