Optical Aberration
The Optical Aberration () plot shows various types of monochromatic aberration that arise when electromagnetic rays are focused by a system of lenses and mirrors. It is available with a 2D Plot Group, and you select it from the More Plots submenu. Add a Height Expression subnode if required.
An Intersection Point 3D data set (see Intersection Point 2D and Intersection Point 3D) pointing to a Ray (Data Set) data set must be used. The data set must point to an instance of the Geometrical Optics interface in which the optical path length is computed.
In addition, in the settings window for the Intersection Point 3D data set, Hemisphere must be selected from the Surface type list. The Center of the hemisphere corresponds to the focus, and the Axis direction points from the focus toward the center of the exit pupil in the focusing system.
Go to Common Results Node Settings for links to information about these sections: Data, Title, Range, Coloring and Style, and Inherit Style. For Optical Aberration plots, only Intersection Point 3D data sets are allowed as inputs.
The Optical Aberration plot is available with the Ray Optics Module.
Zernike Polynomials
Select the Length unit in which the weighted Zernike polynomials will be plotted. The default is the micron (μm). This input is disabled if the model is dimensionless.
The optical path difference among all rays that pass through the exit pupil is computed. Then a linear least-squares fit is used to express the optical path difference as a linear combination of a standard set of orthogonal polynomials on the unit circle, called Zernike polynomials. The polynomials are scaled by the coefficients that are computed by the least-squares fit, called the Zernike coefficients.
Select a Maximum polynomial order: 2, 3, 4, or 5 (the default).
Select an option from the Terms to include list: All, All higher-order terms, or Select individual terms:
•
If All is selected, all Zernike polynomials up to the specified Maximum polynomial order are included in the plot.
•
If All higher-order terms is selected, all Zernike polynomials up to the specified Maximum polynomial order are included in the plot, except for the terms of order 0 and 1. These terms indicate misalignment or misplacement of lenses within an optical system and are less useful for measuring lens quality.
•
If Select individual terms is selected, check boxes appear for all Zernike polynomials. The common names of the polynomials are included where applicable. Select or clear the check boxes to determine which terms should be included in the plot.
Enter a Number of grid points, which must be an integer between 100 and 1,000,000. Increasing the number of grid points increases the number of evaluations of the Zernike polynomials on the unit circle; this improves the quality of the plot but does not affect the calculation of the Zernike coefficients.
A list of Zernike polynomials and their derivation, properties, and references are included in the Ray Optics Modeling chapter of the Ray Optics Module User’s Guide.
Position
Specify the position of the center of the unit circle. The default center location is the origin, (0,0). By assigning nonzero components to the center location it is possible to view multiple types of optical aberration in the Graphics window side-by-side.