Moving optical elements

Optical elements that implement the BeamletOptics.AbstractObject interface, as well as the BeamletOptics.AbstractShapes they are built from, can be moved with the commands listed in the Kinematics section. When objects are manipulated, they are translated and rotated around their self-defined center of gravity, i.e. their position. Their orientation defines their local fixed coordinate system.

using BeamletOptics

mirror = RoundPlanoMirror(25.4e-3, 5e-3)
translate3d!(mirror, [0, 0.1, 0])     # move 10 cm along the global y-axis
zrotate3d!(mirror, deg2rad(45))       # rotate 45° about z through the mirror position

Objects with multiple shapes

Objects which consist of more than one shape, e.g. a CubeBeamsplitter or a doublet lens, move all of their shapes as one rigid body. Unless the object defines its own reference point, the position and orientation of its first shape are used as the kinematic center, see BeamletOptics.MultiShape.

Groups of optical elements

For the easier representation of a group of BeamletOptics.AbstractObjects that moves as one, the ObjectGroup can be used. Refer to the Lens groups example for more information. The group's pivot (its center) can be moved without moving its members via set_pivot3d!.

BeamletOptics.ObjectGroup Type

ObjectGroup <: AbstractObjectGroup

A tree-like storage container for groups of objects. Can store individual objects and subgroups. Main purpose is handling of, i.e., groups of lenses.

Fields

• center: a point in 3D space which is regarded as the reference origin of the group

• dir: a 3x3 matrix that describes the common orientation of the group

• objects: stores AbstractObject, can also store subgroups of type AbstractObjectGroup

Each of its objects is traced and interacts on its own, read them via objects(group).

Kinematic

An ObjectGroup implements the kinematic API, see BeamletOptics.AbstractKinematicTrait. The following logic is applied to

• translate3d!: all objects in the group are translated by the offset vector

• translate_to3d!: all objects are moved in parallel such that the group center is equal to the target position

• rotate3d!: all objects are rotated around the center point with respect to their relative position

• set_pivot3d!: moves the group center (the pivot used above) without moving any of its objects

The objects must be either all static or all movable, otherwise the constructor throws an ArgumentError. The group takes that kinematic class, see BeamletOptics.AbstractKinematicTrait.

source

BeamletOptics.set_pivot3d! Method

set_pivot3d!(group::AbstractObjectGroup, pivot)

Moves the kinematic pivot (center) of group to pivot, without moving any of its objects. The pivot is the reference point used by rotate3d!, translate_to3d! and reset_translation3d!; the group orientation is unchanged.

Example

Rotate a lens group about its first surface instead of the group's default center:

group = ObjectGroup([lens1, lens2])
set_pivot3d!(group, position(lens1))
rotate3d!(group, [0, 0, 1], deg2rad(5))   # rotates about lens1's position, not the old center

source

Assemblies: group or multi-shape object

An assembly such as a telescope, a periscope or an interferometer arm can be modeled in two ways, and the choice follows from whether its parts touch:

Parts of the assembly	Model	interact3d
separate, with air between them	an ObjectGroup or an own subtype of BeamletOptics.AbstractObjectGroup	none: each part is traced and interacts on its own
touching and interacting as one, e.g. cemented or with a shared face	an BeamletOptics.AbstractObject with the BeamletOptics.MultiShape trait, like the CubeBeamsplitter	required: the solver hands every hit to the object, which forwards it to the part that was hit

The solver can find out by itself which of several separate parts a ray hits next. Parts that touch need a BeamletOptics.Hint across their shared face, which only the component knows. An own subtype of AbstractObjectGroup adds named parts and an own constructor to a group and needs no interact3d method; its fields and its constructor check are listed in the docstring of BeamletOptics.AbstractObjectGroup, and the agent skill has a complete example in templates/08_custom_group.jl. A MultiShape object without an interact3d method stops every ray that hits it, with the warning No interact3d method defined for the MultiShape object.