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Aberrations

Common Aberration Analyses

Bridge the gap between ray patterns and classical aberration theory.

IntermediateAberrationsNumPy backend12 min read

Introduction

This tutorial demonstrates the various aberration plots and analyses that can be performed in Optiland. Namely, we cover:

  • Spot diagrams
  • Ray fans
  • Y-Ybar plots
  • Distortion / Grid distortion plots
  • Field curvature plots

Core concepts used

analysis.RayFan(lens)
Plots transverse ray aberrations as a function of pupil position. The "DNA" of an optical system's performance.
analysis.FieldCurvature(lens)
Visualizes the Petzval surface and the separation between sagittal and tangential focal planes.
analysis.Distortion(lens)
Quantifies the percentage deviation of image height from the ideal paraxial prediction (y=ftan⁡θy = f\tan\theta).
analysis.RmsSpotSizeVsField()
Plots how the aggregate blur changes as you move from the center to the corner of the image.

Step-by-step build

1

Import analysis modules

python
from optiland import analysis
from optiland.samples.objectives import CookeTriplet
2

Instantiate the Cooke Triplet and draw the lens layout

python
lens = CookeTriplet()
lens.draw()
Step
3

Plot the spot diagram

Spot Diagram

python
spot = analysis.SpotDiagram(lens)
spot.view()
Step
4

Extract field coordinates and compute spot radius statistics

python
fields = lens.fields.get_field_coords()
wavelengths = lens.wavelengths.get_wavelengths()

print("Geometric Spot Radius:")

geo_spot_radius = spot.geometric_spot_radius()
for i, field in enumerate(fields):
 for j, wavelength in enumerate(wavelengths):
     print(
         f"\tField {field}, Wavelength {wavelength:.3f} µm, "
         f"Radius: {geo_spot_radius[i][j]:.5f} mm",
     )

print("RMS Spot Radius:")

rms_spot_radius = spot.rms_spot_radius()
for i, field in enumerate(fields):
 for j, wavelength in enumerate(wavelengths):
     print(
         f"\tField {field}, Wavelength {wavelength:.3f} µm, "
         f"Radius: {rms_spot_radius[i][j]:.5f} mm",
     )
5

Plot the ray fan aberration diagram

Ray fans

python
fan = analysis.RayFan(lens)
fan.view()
Step
6

Plot the Y-Ybar diagram

Y-Ybar plot

python
yybar = analysis.YYbar(lens)
yybar.view()
Step
7

Plot the distortion map

Distortion

python
distortion = analysis.Distortion(lens)
distortion.view()
Step
8

Plot the grid distortion map

Grid distortion

python
grid = analysis.GridDistortion(lens)
grid.view()
Step
9

Plot the field curvature diagram

Field Curvature

python
field_curv = analysis.FieldCurvature(lens)
field_curv.view()
Step
10

Plot RMS spot size versus field

RMS Spot Size vs. Field

python
rms_spot_vs_field = analysis.RmsSpotSizeVsField(lens)
rms_spot_vs_field.view()
Step
11

Plot RMS wavefront error versus field

RMS Wavefront Error vs. Field

python
rms_wavefront_error_vs_field = analysis.RmsWavefrontErrorVsField(lens)
rms_wavefront_error_vs_field.view()
Step
12

Plot the pupil aberration diagram

Pupil Aberration

  • The pupil abberration is defined as the difference between the paraxial and real ray intersection point at the stop surface of the optic. This is specified as a percentage of the on-axis paraxial stop radius at the primary wavelength.
python
pupil_ab = analysis.PupilAberration(lens)
pupil_ab.view()
Step
Show full code listing
python
from optiland import analysis
from optiland.samples.objectives import CookeTriplet

lens = CookeTriplet()
lens.draw()

spot = analysis.SpotDiagram(lens)
spot.view()

fields = lens.fields.get_field_coords()
wavelengths = lens.wavelengths.get_wavelengths()

print("Geometric Spot Radius:")

geo_spot_radius = spot.geometric_spot_radius()
for i, field in enumerate(fields):
  for j, wavelength in enumerate(wavelengths):
      print(
          f"\tField {field}, Wavelength {wavelength:.3f} µm, "
          f"Radius: {geo_spot_radius[i][j]:.5f} mm",
      )

print("RMS Spot Radius:")

rms_spot_radius = spot.rms_spot_radius()
for i, field in enumerate(fields):
  for j, wavelength in enumerate(wavelengths):
      print(
          f"\tField {field}, Wavelength {wavelength:.3f} µm, "
          f"Radius: {rms_spot_radius[i][j]:.5f} mm",
      )

fan = analysis.RayFan(lens)
fan.view()

yybar = analysis.YYbar(lens)
yybar.view()

distortion = analysis.Distortion(lens)
distortion.view()

grid = analysis.GridDistortion(lens)
grid.view()

field_curv = analysis.FieldCurvature(lens)
field_curv.view()

rms_spot_vs_field = analysis.RmsSpotSizeVsField(lens)
rms_spot_vs_field.view()

rms_wavefront_error_vs_field = analysis.RmsWavefrontErrorVsField(lens)
rms_wavefront_error_vs_field.view()

pupil_ab = analysis.PupilAberration(lens)
pupil_ab.view()

Conclusions

  • Demonstrated eight analysis tools available in the optiland.analysis module on a Cooke Triplet: SpotDiagram, RayFan, YYbar, Distortion, GridDistortion, FieldCurvature, RmsSpotSizeVsField, RmsWavefrontErrorVsField, and PupilAberration.
  • Each analysis object follows the same two-step pattern — instantiate with the lens object, then call .view() — making the API consistent and easy to remember.
  • The YYbar diagram and distortion plots reveal field-dependent behavior, while the field curvature and pupil aberration plots highlight residual Seidel terms across the pupil.
  • RMS spot size and RMS wavefront error vs. field provide a quick scalar summary of image quality, useful for comparing design iterations at a glance.

Next tutorials

Next1st & 3rd Order AberrationsDecompose performance into classical Seidel coefficients (S1 to S5).RelatedRaytracing AspheresSee how aspheric surfaces can be used to specifically target these analyzed aberrations.

Original notebook: Tutorial_3a_Common_Aberration_Analyses.ipynb on GitHub · ReadTheDocs