Description:

This feature introduces a visualization for analyzing the sag of an optical surface. It will display a 2D heatmap of the surface sag along with a 1D cross-sectional profile. This provides both an overall view of the surface shape and a detailed look along a specific axis.

Current Implementation (Proof of Concept):

The current proof-of-concept code performs the following steps:

1. Data Generation:

   • Generates a 2D grid of (x, y) coordinates using be.linspace and be.meshgrid.
   • Calculates the sag values for these coordinates on a specified surface (e.g., lens.surface_group.surfaces[4]) using the geometry.sag(X, Y) method. This results in a 2D sag map.
   • Calculates a 1D sag profile along the x-axis (where y=0) using the same geometry.sag(x, y_value) method.

2. Plotting using Matplotlib and GridSpec:

   • A figure is created with a specific layout managed by gridspec.GridSpec. This ensures proper alignment of the 2D map, its colorbar, and the 1D profile plot.
   • 2D Sag Map (Top Subplot):
     • Displays the sag_map_2d as a filled contour plot (contourf).
     • A colorbar is added to a dedicated axes (cax) to show the sag (z) scale.
     • A horizontal dashed red line is drawn at y=0 on the map to indicate the location of the x-axis profile.
     • The plot is titled (e.g., "2D Sag Map for Surface S2"), and y-axis is labeled.
     • ax_map.axis("equal") ensures correct aspect ratio.
     • X-tick labels are hidden as this axis is shared with the profile plot below.
   • 1D X-Axis Sag Profile (Bottom Subplot):
     • Plots the sag_profile_x (sag values along y=0) against the x-coordinates.
     • This plot shares its x-axis with the 2D map above for direct correlation.
     • Styled with a red dashed line.
     • X and Y axes are labeled ("X-coordinate", "Sag (z)").
     • A grid is enabled for better readability.
     • Y-limits are adjusted to fit the profile data with some padding.

Visual Output Example (from current code):

Proposed Enhancements / Next Steps:

1. Add Y-Axis Cross-Section Profile:

   • Currently, only the x-axis profile (y=0) is plotted. We need to add another 1D plot showing the sag profile along the y-axis (x=0).
   • This would involve:
     • Calculating sag_profile_y similar to how sag_profile_x is done:

       # y_values_profile = y_grid_coords # Use the same y grid points
       # x_value_for_profile = 0
       # sag_profile_y = lens.surface_group.surfaces[SURFACE_INDEX].geometry.sag(
       #     x_value_for_profile, y_values_profile
       # )

     • Modifying the GridSpec layout to accommodate a third subplot for this y-axis profile. This might involve changing GridSpec to have 3 rows or arranging it differently (e.g., heatmap on left, two profiles stacked on the right, or vice-versa).
     • Plotting sag_profile_y against y_values_profile.
     • Adding a vertical dashed line on the 2D sag map at x=0 to indicate the location of this new y-axis profile.
     • Ensuring appropriate labeling and legends for the new plot and the indicator line on the map.

2. User Interactivity (Future Considerations):

   • Allowing the user to select which surface to analyze.
   • Potentially allowing the user to click on the 2D map to define custom cross-section lines.