I have a system with a mirror at 45 deg tilt. I invoked the tilt and bend option on the tilted mirror in order to set the remaining surfaces at the correct 90 deg orientation.

However, now I want to see the effect of tilting (or decentering ) the mirror alone with respect to the other components, i.e. without shifting the components after the mirror. How can I do this?

Synopsis

Keeping post-scan mirror surfaces in a static location

Solution

Two of the best ways to implement this are described below. We suggest you try them both so you get used to trying different coordinate break approaches.You should already have some knowledge of the Coordinate Data Setup dialog in order to follow the discussion: 1) A) For purposes of discussion, let's assume that your tilt and bend mirrored surface is surface 4. B) Set up your system in the nominal position you want (with surface 4 tilted at 45 degrees and the tilt and bend option on). The subsequent surfaces will also be in their nominal positions. C) Make surface 5 to be a coordinates=global surface using appropriate option in the coordinate data setup window of surface 5. In the process of doing this, you will be asked to "Enter global reference surface". Choose any surface before the tilt and bend surface (surface 1 is OK). This essentially freezes surface 5 into a global position relative to surface 1. D) Now when you change the tilt on surface 4, the position of surface 5 will be frozen in space relative to surface 1 and all subsequent surfaces (6+) will not change with the tilt of surface 4. 2) A) For purposes of discussion, let's assume that your tilt and bend mirrored surface is surface 4. B) Set up your system in the nominal position you want (with surface 4 tilted at 45 degrees and the tilt and bend option on). The subsequent surfaces will also be in their nominal positions. C) Add a new surface 5 right after your surface 4 D) This new surface will be a "dummy" surface with the exact same vertex location as surface 4. In order to do this, you need to transfer the thickness of surface 4 (if there is one) to the new surface 5. E) Now remove the tilt and bend option on surface 4 but keep the tilt of surface 4 at 45 deg and make sure that the "Coordinate Return" option is set to "Yes" so that the coordinate system returns to the untilted coordinate state of surface 4 before moving on to the next surface (surface 5). F) Now your surfaces 5+ in the system will have no tilt at all. This is fine. G) Now add 2X the tilt onto surface 5. That is: make surface 5 have a tilt of 90 degrees. H) Now when you change the tilt on surface 4, no matter what that tilt is, the coordinate system will automatically return to the untilted state before moving onto surface 5. Surface 5 will then have a non-varying tilt of 90 degrees and all subsequent surfaces (6+) will not change with the tilt of surface 4. Both of these approaches will also correct the displacement of surfaces 5+ if surface 4 is translated (moved in x, y or z).