GratingArrayStructure

class marxs.design.rowland.GratingArrayStructure(**kwargs)

Bases: ElementsOnTorus

Collection of diffraction gratings on the Rowland Torus

When a GratingArrayStructure (GAS) is initialized, it places elements in the space available on the Rowland circle, most commonly, this class is used to place grating facets.

After generation, individual facet positions can be adjusted by hand by editing the attributes elem_pos or elem_uncertainty. See Parallel for details.

After any of the elem_pos, elem_uncertainty or uncertainty is changed, generate_elements needs to be called to regenerate the facets on the GAS.

Parameters

radiuslist of 2 floats

Inner and outer radius of the GAS as measured in the yz-plane from the origin.

phifloat or list of 2 floats

Bounding angles for a segment covered by the GSA. \(\phi=0\) is on the positive y axis. The segment fills the space from phi1 to phi2 in the usual mathematical way (counterclockwise). Angles are given in radian. Note that phi[1] < phi[0] is possible if the segment crosses the y axis. Alternatively, phi can just be a single number. In that case, there will be exactly one element per radius.

Define a new MARXS element.

Methods Summary

distribute_elements_on_arc(radius)	Distribute elements on an arc.
distribute_elements_on_radius()	Distributes elements as evenly as possible along a radius.
elemposyz()	Specify the element position in the yz plane
max_elements_on_arc(radius)	Calculate maximal number of elements that can be placed at a certain radius.
max_elements_on_radius(radius)	Distribute elements on a radius.

Methods Documentation

distribute_elements_on_arc(radius)

Distribute elements on an arc.

The elements are distributed as evenly as possible over the arc.

Note

Contrary to distribute_elements_on_radius, elements never stretch beyond the limits set by the phi parameter of the GAS. If an arc segment is not wide enough to accommodate at least a single element, it will go empty. (The exception to that is is phi is a single value. In that case, there will be exactly one element.)

Parameters

radiusfloat

radius of arc where the elements are to be distributed.

Returns

centeranglesarray

The phi angles for centers of the elements at radius.

distribute_elements_on_radius()

Distributes elements as evenly as possible along a radius.

Note

Unlike distribute_elements_on_arc, this function will have elements reaching beyond the limits of the radius, if the distance between inner and outer radius is not an integer multiple of the element size.

Returns

radiinp.ndarray

Radii of the element center positions.

elemposyz()

Specify the element position in the yz plane

For the torus, the Rowland circle lies in the xy plane and the symmetry axis of the torus is the y-axis. In this class, the position of the elements is specified in the yz plane in the coordinates of the torus and the remaining coordinate.

This function will be customized by derived classes.

Returns

ypos, zposnp.array

1D arrays of y and z positions for the elements distributed in 2D.

max_elements_on_arc(radius)

Calculate maximal number of elements that can be placed at a certain radius.

Parameters

radiusfloat

Radius of circle where the centers of all elements will be placed.

max_elements_on_radius(radius)

Distribute elements on a radius.

Parameters

radiuslist of two floats

inner and outer radius that should be covered by elements

Returns

nint

Number of elements needed to cover a given radius segment. Elements might reach beyond the radius limits if the difference between inner and outer radius is not an integer multiple of the element size.