The document discusses the advantages of freeform aspheric telescopes, highlighting their ability to explore design variations not possible with conventional aspherics. It presents a specific design that improves baffling by modifying mirror tilts, resulting in optimal image performance. Additionally, it indicates that further optimization could yield even better performance from these designs.

1. Design variations for freeform aspheric telescopes
David Shafer
David Shafer Optical Design

2. • Freeform aspherics allow for design variations that are
impossible with conventional aspherics
• Once a good freeform aspheric design has been found, based
on a conventional aspheric design, new variations can be
explored
• These may have advantages such as better baffling

3. This freeform design is
based on a conventional
aspheric design

4. Freeform aspherics allow this to
become an unobscured design
with a good image location
f/2.0, 10 degree
diameter flat field,
spot size = 20 arc
seconds over the
field.

5. This design has a problem
with baffling, where light
hits the third mirror without
hitting the first mirror

6. By using different
signs of the tilts on
the second and third
mirrors this new
configuration of
mirrors results,
which is very much
better for baffling.
The flexibility of
freeform aspherics
the allows this
design to also have
good performance,
similar to that of the
previous design.
f/2.0, 10 degree diameter
flat field, spot size = 20 arc
seconds over the field.

7. These designs are only partially optimized and
better performance is probably possible
This shows how alternate versions of a
freeform aspheric design may exist with
desirable properties like good baffling.