How to Convert Positions and Dependencies in QUADOA® Optical CAD
In QUADOA® Optical CAD you can change how an element’s position is defined at any time, even after the whole system is set up, without moving the element. Positions can be converted between absolute and relative definitions, the rotation order can be swapped, and the pivot point can be moved. Correct dependencies are essential for accurate tolerancing, so you can build the system in the most convenient way first and adjust the dependencies afterwards.
Key points
- Right-click an element in the Optical Design Editor and choose Convert Position.
- Options: to Absolute, Relative to previous, Relative to sibling and Absolute in Z.
- The values change, but the position in 3D space stays the same.
- Absolute in Z changes only the Z position and is important for stack mountings.
- The rotation order and the pivot point can also be converted.
Terms used in this article
- Position dependency
- The reference an element’s position is defined against, such as the global origin or a previous element.
- Sibling
- Another element on the same level, for example in the same assembly.
- Stack mounting
- A mount where lenses are stacked on each other, so their positions depend on each other.
- Rotation order
- Whether an element is first rotated and then positioned, or the other way round.
Why convert positions and dependencies?
For a tolerance analysis, it matters how elements depend on each other: is a lens positioned relative to the previous lens, absolute in the housing, or stacked on another lens in the same mount? QUADOA® lets you set up the system in the most convenient and intuitive way and then convert all dependencies afterwards, without changing the element positions.
How to convert the position definition
- Right-click the element in the Optical Design Editor.
- Choose Convert Position and one of the options below.
| Option | Result |
|---|---|
| Convert to Absolute | Position refers to the global coordinate system |
| Convert to Relative to previous | Position refers to the previous element |
| Convert to Relative to sibling | Position refers to a sibling element |
| Convert to Absolute in Z | Converts to “Absolute (Relative Z)”: X, Y and rotation absolute, Z the sum of the preceding Z positions in the assembly; important for tolerancing stack mountings |
In each case the position values change, for example the Z value, but the element stays at the same place in 3D space. To convert the positions of the whole model at once, for example to make all positions absolute, use Convert Position in the menu bar of the Optical Design Editor.
Note: Conversion is not possible while the position of an element depends on a slider or multi-config parameter.
For the difference between the options, see absolute and relative positions.
How to convert the rotation order
Two parameters control the order, and both can be converted without moving the element:
- Rot Order: the order in which the rotations about X, Y and Z are applied. Options: XYZ, XZY, YXZ, YZX, ZXY and ZYX; the default is ZYX.
- Pos/Rot Order: whether the element is first positioned and then rotated (Pos first), first rotated and then positioned in the rotated coordinate system (Rot first), or first moved along Z, then rotated and finally decentered in X and Y (Z Pos XY).
Since the order affects both position and rotation, it is important for correct results. The conversion recalculates the values for the new order, so the element stays in place.
How to convert the pivot point
In the video, a lens has its pivot point at (−150, 0, 0) and rotates around it. After converting the pivot point to (0, 0, 0), the X, Y, Z positions and rotations are recalculated, the lens stays in place, and it now rotates around its own center. More on pivot points: pivot points for lenses and assemblies.
Video tutorial: converting positions and dependencies
This 3-minute video shows all Convert Position options, the rotation order and pivot point conversion.
Video length: 3:05 min · Also on YouTube: Convert Positions and Dependencies in QUADOA® Optical CAD
Frequently asked questions
Yes. Right-click the element in the Optical Design Editor and choose Convert Position. The values are recalculated so the element stays at the same place in 3D space.
It converts only the Z position to absolute, which is important for correct tolerancing of stack mountings.
Rotating first and then positioning gives a different result than positioning first and then rotating. Converting the rotation order recalculates the values so the element stays in place.
Yes. Converting the pivot point recalculates positions and rotations, so the element does not move but rotates around the new pivot point.
Conversion is not possible while the element’s position depends on a slider or multi-config parameter. Replace the parameter with a value first.
ZYX. Six orders are available: XYZ, XZY, YXZ, YZX, ZXY and ZYX.