SRW Propagation Parameters

Propagation Parameters

SRW manages wavefront propagation using so-called "Propagation Parameters":

The propagation parameters are specified for each optical element and drift in both Sirepo and SRW to transform the wavefront to allow better resolution and to achieve the desired field of view at the necessary watch point.

Description of the propagation parameters

(format: [number of column]. description)

1. Auto-Resize (1) or not (0) Before propagation.
2. Auto-Resize (1) or not (0) After propagation.
3. Relative Precision for propagation with Auto-Resizing (1.0 is nominal).
4. Type of the propagator:

• 0 - Standard - Fresnel (it uses two FFTs);
• 1 - Quadratic Term - with semi-analytical treatment of the quadratic (leading) phase terms (it uses two FFTs);
• 2 - Quadratic Term - Special - special case;
• 3 - From Waist - good for propagation from "waist" over a large distance (it uses one FFT);
• 4 - To Waist - good for propagation to a "waist" (e.g. some 2D focus of an optical system) over some distance (it uses one FFT).

5. Do any Resizing on Fourier side, using FFT, (1) or not (0).
6. Horizontal Range modification factor at Resizing (1.0 means no modification).
7. Horizontal Resolution modification factor at Resizing (1.0 means no modification).
8. Vertical Range modification factor at Resizing (1.0 means no modification).
9. Vertical Resolution modification factor at Resizing (1.0 means no modification).

Partially implemented in SRW, but not used in Sirepo yet:

10. Optional: Type of wavefront Shift before Resizing (vs which coordinates; to be implemented).
11. Optional: New Horizontal wavefront Center position after Shift (to be implemented).
12. Optional: New Vertical wavefront Center position after Shift (to be implemented).
13. Optional: Orientation of the Output Optical Axis vector in the Incident Beam Frame: Horizontal Coordinate.
14. Optional: Orientation of the Output Optical Axis vector in the Incident Beam Frame: Vertical Coordinate.
15. Optional: Orientation of the Output Optical Axis vector in the Incident Beam Frame: Longitudinal Coordinate.
16. Optional: Orientation of the Horizontal Base vector of the Output Frame in the Incident Beam Frame: Horizontal Coordinate.
17. Optional: Orientation of the Horizontal Base vector of the Output Frame in the Incident Beam Frame: Vertical Coordinate.