Introduction

Apart from dictionaries, PyPO also employs a few classes as datatypes. These are mostly results from calling System methods. On this page, we will explain these classes in more depth. These explanations are more high level, for a lower level overview we refer to the datatype classes reference.

The "reflGrids" Object

As mentioned, a reflector in PyPO is nothing more than a dictionary with a specific set of parameters. This is done in order to be more economic with the memory. However, when a reflector has to be plotted, or when PO calculations have to be performed, the actual grids need to be generated. Methods in System that need these grids generate them themselves, but there is a method present that users can call to generate the grids themselves: the generateGrids() method. This method accepts the name of a reflector as positional argument and returns a reflGrids object.

The grids object contains the xyz co-ordinates of the reflector surface, the xyz normal components and the area elements at each point on the reflector.

The "frames" Object

A frame is an object describing a collection of rays. It consists of the xyz co-ordinates of each ray and the xyz direction components of each ray. In addition, the size of the frame, which is the number of rays, is also a member of the object.

The frame object also contains a "snapshots" member. This is for storing transformation matrices, which transform the frame. It is possible to store several atrices and in this way it is possible to revert back to a previous snapshot.

The frame object contains a single method (apart from its constructor), named setMeta(). This method sets meta information of the frame, such as a position tracker (used for absolute translations), an orientation tracker (for absolute rotations) and a transformation matrix (which sets the total transformation).

The "PO fields" and "PO currents" Objects

The PO calculation results are stored in either a fields or currents object. They both inherit from the resContainer base class.

The fields object contains six relevant members. These represent the xyz components of the complex-valued electric (E) and magnetic (H) fields. These are both taken into account in order to properly take polarisation into account.

The currents object is very similar to the fields object, except that now it contains the electric current (J) and magnetic current (M). These currents are induced by the E and H fields and calculated using the boundary conditions for reflection of electromagnetic fields.

Both objects have a method called setMeta(). This method accepts the name of the surface on which the fields or currents are defined and the wavenumber "k", in 1/mm, belonging to the fields or currents. The other methods, T() and H(), take the transpose and Hermitian transpose, respectively, of each component of the fields or currents object.

It is possible to index these objects. Iteration goes through E (J) first and then through H (M), and for each of these it iterates through the xyz components.

The final object in the PO datatype collection is the scalarfield. This object contains one single member, the scalar field itself. The setMeta() method is present as well and is identical to the one for the regular fields and currents objects.