Double-Surface Elements are restricted with two nonintersecting plane optical surfaces and one or two boundary surfaces. There are two types of double-surface Elements integrated into Application -- Glass Plates and Lenses. Note generally it is the same object. The single difference is predefined shape of Surfaces combined into Double-Surface Element (Plane Surfaces for Glass Plate and Spherical Surfaces for Lens)
The Pivot Point of Double-Surface Element is located at its first surface. As it shown above, 0X axis is longitudinal (optical) one of it. If the Plate or Lens is the solid of revolution, 0X axis is the axis of revolution.
As it illustrated with figure below, hierarchical structure of Double-Surface Elements consists of two Single-Surface Element, Optical Material, and one or two Boundary Properties (depending on shape of Element):
Generally, editing of properties of Double-Surface Element does not differ from Single-Surface Elements. That's why just points specific for Double-Surface Elements will be described here.
To create Double-Surface Element:
There is some specificity dealing with affecting form-factor of Double-Surface Element. First, you are able to define Shape of both Surfaces combined into Element (whole set of Simple and Aspherical shapes as well as representation as Triangular Mesh are available). Second, you can affect Boundaries of Double-Surface Element editing Clear Apertures of Surfaces. Finally, you can define Location and Orientation of second Surface with respect to first one affecting thickness of Element and mutual position of its Surfaces. All changes can be provided via editing of parameters within Transformation group of properties of back surface.
To define thickness of Double-Surface Element:
To define eccentricity of back surface with respect to first one:
Note position of second Surface is defined with respect to first one (i.e. with respect to Pivot Point of Double-Surface Element). So, Coordinate Mode settings will not affect coordinates of second Surface.
To define orientation of back surface with respect to first one:
Note rotation will be provided around current position of origin of internal coordinate system of back surface.
Note if you will change Optical Material to air, both internal and external boundaries of that Element will be disabled. Element will be considered as a set of sequential surfaces. Example of such kind of Element with corresponding hierarchical structure is shown below:
Optical Material - BAF4 glass from Schott Catalogue
Optical Material - Air from Misc. Catalogue
Nevertheless, you are able to create Double-Surface Element containing internal and external boundaries with air inside. To do it, you have to define air material not from catalogue but with manually printing of "Air" (or any other name you want) as a material name. In this case, Optical Material inside Element will be considered as air but you will able to define Optical Properties of Element's Boundaries. Example of such kind of Element is shown below: