Light Guide Body Parameters

This page provides detailed information on the Light Guide body parameters.

Guide Curve

The Guide Curve represents the curve along which the profile is swept to create the Light Guide.

This curve is not necessarily continuous in tangency.

Body Type

The body type allows you to determine what to base the body construction on (specific shape, curve or diameter).

Note: Prisms are built according to the Guide Curve in their middle. The profile you select has no relation to the prisms position and may be shifted.

Prisms only The prisms are created but not the Light Guide body. This mode is useful when wanting to use a custom light guide body.


Add operation: the height of the prisms is defined to reach the guide curve.

Important: Up to 2023 R1, a 0.1mm gap is applied automatically between the prisms and the Guide curve. From 2023 R2, the 0.1mm is no longer applied.

Remove operation: the height of the prisms is not reliable, it is only used for assembling.

CAUTION: The visual rendering of a Prism only remove operation corresponds to the negative of the prisms. In other words, it displays the prisms part to be physically removed.
Constant profile

The body is created using a profile defined by a planar surface and located at the start of the guide curve. Then the profile is swept along the guide curve to create the light guide body.


Circular shape The body is created using a circular shaped profile. The profile diameter allows you to set the diameter of the profile.


Extra body height Extra body height corresponds to body height added from the guide curve in the opposite direction of the prisms.

Extra body height = 0mm

Extra body height = 1mm

Prism Orientation

The prism orientation type allows you to determine how the prism should be oriented in relation to the light guide body.

Direction

All the prisms have the same orientation all along the guide curve. Light extracted through the prisms has the same direction.

This type is particularly suited for linear light guides.

Figure 1. Linear light guide with optical axis in magenta
Figure 2. Prisms of the light guide
Normal to Surface

All the prisms have potentially a different orientation. Light extracted through the prisms has a different direction all along the guide curve.

This type is suited for non-linear light guides.

Figure 3. Circular Light Guide for cup holder
Figure 4. Prisms of the light guide

The position/orientation of the prisms is driven by two elements, a surface and the optical axis.

  • The optical axis provides the average orientation in which the light is going to be extracted from the light guide. The optical axis must be positioned at the very beginning of the guide, whatever the first prism is positioned (Start = 0 or Start = X).

  • The selected surface determines the prisms' orientation. To avoid construction issues, the whole guide curve needs to lay on the normal surface.

    The normal surface width should equal or exceed the light guide and the built prisms.

    To create a correct surface, we recommend to create a line at the start of the guide curve defining the optical axis. Then, use the Pull command to sweep this line all along the guide curve.

    Figure 5. Light Guide surface input in pink - The position/orientation of the prisms is driven by the surface
Variable Direction

Defining multiple optical axes ensures you to have a smooth variation of lit appearance when the observer direction is changing. This can also be useful to pass regulations like such as sidemarker (where some light need to be sent to the side) in addition to Position Lamp.

Each green arrow represent the optical axis and its position along the guide.

Operation

The Operation corresponds to the prisms generation on the Light Guide.

Add/Remove/Hybrid operations allow to remove/add prisms to the light guide body.

Add
Remove
Hybrid Hybrid operation is based on the prisms parameters to determine whether a prism is added or removed from the light guide.

Distances

Mode

Curvilinear The parameters Start, End, Step and Length (for add/remove operations) are curvilinear distances based on the guide curve.

  • In Direction prism type, the distance are measured directly on the guide curve.
  • In Normal to Surface prism type, the distances are measured on an offset of the guide curve passing by the middle of the top edge of the prism.
Projection

The parameters Start, End, Step and Length (for add/remove operations) are defined as curvilinear distances based on the guide curve projected on a projection plane.

The Projection Axis corresponds to a line that defines the projection plane (plane normal to Projection line).

Note: With this model, you can obtain style effects as a constant prism length when the Light Guide is seen in a specific direction.

Start & End

Start and End define the size of the prism-free zones at the beginning and at the end of the guide curve.

The beginning of the guide curve is the extremity where the source is located.

Note: Start value is always respected, however in come cases End value might not be respected because the last prism is not cut by this parameter. Prisms are created to respect the End value as much as possible.

Half of the first prism is included in the Start distance. If Start is null, the first prism will start by its top at the beginning of the guide curve.

Start

End
Prism-free zones