HOW TO SET UP A SEQUENCE OF OPTICAL AXES
(c) 2015 M.Lampton
STELLAR SOFTWARE
The easy way is to use coordinate breaks. A "CB" is a pair of
plano surfaces in in your optical system, named CBin and CBout.
The job of CBin is to interrupt the ray trace and capture the
local coordinates {x,y,z,u,v,w} of each ray. The job of CBout
is to restart the ray trace at its surface, using the coordinates
that were captured by CBin.
If CBin and CBout were located at the same position and had
the same orientation, the pair would accomplish nothing. But
of course these surfaces can have differing {X,Y,Z} locations,
obliging the rays to jump off from a new location. This feature
means that to explore lateral tolerances of elements or groups,
you need not move the group: move the rays instead.
A more valuable feature is that they may have different orientations.
If their roll angles differ then the beam will be twisted at their
common location. If their tilt or pitch angles differ, then the beam
will be redirected. An example is shown in Figure 9-19 of the BEAM
FOUR GUIDE. This feature is useful in assessing tolerances of
elements or groups to tilt, pitch, or roll. This feature allows a bent
optical system to be described by a straight-line coaxial system that
includes one or more CB pairs. CBs can be autoadjusted, allowing
BEAM FOUR to find the best new axis locations and/or orientations.
An alternative way is to use trigonometry, placing every optical
element into a common coordinate frame mathematically. An
example is given in the file DISK.OPT included in the product
distribution.
