Fields (aperture and screen) for below-given parameters:
Preselected sets of parameters
These systems are reduced to a few describing parameters:
- Extent of numerical field sizes (in mm; the field will be calculated on a grid of 512x512 pixels)
- Wavelength (in nm)
- Shape of initial field as an aperture which posesses one parameter (circular or gaussian aperture) or two (rectangular aperture)
- First distance of propagation Z1 to a lens
- Focal length f of lens (in mm; entering 0 means "no lens at all")
- Second distance of propagation Z2 to the screen
A drop-down-menu offers a few predefined sets of parameters which are known to produce reasonable results. They will be inserted and calculated by pressing "Insert values".
Pressing "evaluate" or the "enter-key" the numerical propagation by means of fourier transformation will be initiated and the result displayed.
This calculation can take a few seconds.
Due to the use of the Fourier-Approximation for the propagation and the relatively low resolution it is easily possible to generate numerical artifacts! This happens particularly if the field intensities at the edge of the field are not zero.
Background: if the field extends to the edge of the numerical matrix "reflections" and "interference effects" take place which do not correspond to a free propagation but rather simulate the propagation through a mirrored rectangular pipe. Also the discrete steps of the calculation matrix influences the appearance of the field.