Dream's owner and founder,
Shane Santi, started learning about thermal aspects that degrade
mirror performance and optical systems well over 20 years ago.
Early scientific papers that quantified mirror seeing educated him to the surprisingly large amount of
losses and quickly
led him to understand the value of pursuing lightweight mirrors.
He formed Dream to not only solve a problem but to combine two
complementary technologies; engineered lightweight mirrors and
engineered carbon fiber structures. Both provide a technology-driven
performance leap and when combined create an enabling, disruptive
product to traditional technologies.
Shane recognized that most
lightweight mirrors were either moderately difficult to extremely
difficult to process to the same smooth levels as solid mirrors.
This is the problem he knew had to be solved, in order to achieve
total performance. He recognized that intelligent designs and
higher levels of modern engineering could be used to greatly
reduce print through, as well as evaluate the mirrors for not
just polishing displacements but also gravity displacements.
The latter has to include the mirror mount, which is why Shane
designs both the lightweight mirror and the mirror mount at the
same time. He has been designing lightweight optical mirrors with FEA feedback iterations since 2003 and
has more individual design and empirical use experience creating
optimized lightweight glass mirrors than any other individual
in the world.
"Your company does phenomenal
work. There is a lot of thought and heart that goes into your
products. Dream's engineering sets their lightweight mirrors
apart from competitors. Your engineering goes beyond the lightweight
aspect. You focus on actual performance!"
- Ted Kamprath
39 years in professional optics,
using everything from million dollar test rooms to 144"
Dream is at the forefront
of lightweight glass mirror technology with the disruptive performance
that comes with Dream's thin-featured zeroDELTA
mirrors. These mirrors
are the culmination of 15 years of continuous and relentlessly
improvements, chasing performance and becoming a vertically-integrated
company that has always had the fundamental principal that there
should be just as much engineering in the geometry of the mirror
as the mirror mount. Because these mirrors are produced in-house
it gives Dream control over as-designed versus as-cast variance,
developing new rib geometries, annealing, scheduling/delivery,
and an ability to quickly modify a design from the archives.
Bringing generation, grinding and polishing in-house has further
and completely closed the design loop.
When the 3D design of the
optic is optimized (20-30 FEM/FEA iterations is the average per
mirror) around an initial support architecture (mirror mount),
then modified in thickness, height, adding and moving sub ribs,
adding back flanges, etc., it gives Dream's lightweight, engineered
mirrors superb performance that is unrivaled in the nearly 100
year history of lightweight mirrors. See hard data; 1, 2 , 3 and 4.
"We shall look back and see how inefficient,
how primitive it was to work with thick, solid mirrors, obsolete
- George Willis Ritchey 1928: JRASC,
Vol. XXII, No. 9, November 1928.
While developing the lightweight
mirrors Dream was simultaneously becoming a specialist in carbon
fiber and especially CF skinned sandwich
core. Like other portions
of the opto-mechanical system that Dream has taken over, it is
not surprising that a generic composite company would not have
the desire or appreciation to make the composites to a much higher
standard, which is a neccessity for the extremely tight mechanical
and thermal tolerances required for opto-mechanical systems.
Dream's largest custom-built (by Dream) composite oven
is 12' wide and maintains temperature a full magnitude tighter
than OTS aerospace composite ovens.
Dream's dedicated carbon fiber
mirror mounts, backplates, platforms, large diameter tubes, trusses,
etc., in combination with the Dream zeroDELTA lightweight
mirrors produce athermal
assemblies with ununusually
high stiffness and low mass. They are better equipped and provide
higher performance for today's optical systems with ever-tightening
tolerances. Dream's composite parts have unusually high consistency
from part to part and full instrument to full instrument; performance
lives in the details. In this way the design and engineering
loop has been further closed because Dream not only produces
lightweight mirror blanks but also proceses them and uses them
in full instruments, allowing Dream to easily surpass
the performance of traditional technologies.
Shane has also been learning
optics since 1994. This deep, broader-based, real-world (empirical)
knowledge, coupled with vertical integration of all tasks related
to processing of the mirrors allows Dream to maximize a mirror's
design & features in every way. Real-world information is
fed back into the designs and makes Shane's knowledge, experience
and heritage unique. Dream is creating mirrors that are not just
light, stiff and with a much shorter thermal time constant, but functionally optimized to a degree
never seen before, making them both enabling and disruptive.
Dream's zeroDELTA lightweight
mirrors were developed through our casting technology. Prior
to starting Dream fusing and frit bonding technologies were investigated.
Those techniques use individual glass components that are cut,
assembled, then fused or frit-bonded together at lower temperatures.
These methods have fundamental hurdles that make it extremely
difficult to vary specific rib thicknesses, create varying sub
ribs, tapered ribs, etc. Dream's cast technology offers the highest
level of design freedom and therefore far greater
mechanical optimization than other methods, which is
one of two main reasons high-temperature cast technology was
Dream's mirrors are cast (melted)
to produce a single, continuous mirror that does not suffer from
the historically significant problem of bondline issues, which
is why Dream chose not to pursue less expensive, lower temperature
fused and frit-bonded mirrors. Since Dream's mirrors are cast
they don't need expensive inspection equipment, techniques and
expertise in order to uncover areas of the mirror where less
than 100% bonding took place. Openly available papers have shown
that even companies with 20-30 years experience with these lower
temperature processes continue to have bondline issues. Dream's
mirrors don't have to "act" like one piece of glass.
They are one piece of glass. They won't come apart today,
tomorrow or 50 years from now. The optical surface of the mirror
is typically finished to fractions of a wavelength of light.
The mirror doesn't need to come apart in order to have catastrophic
The zeroDELTA lightweight
mirrors are not pocket-milled from a solid mirror blank or boule
either. Pocket-milling is also limited in its design freedoms
for; rib types, depths, shapes, radii in corners, back flange
widths, etc. Pocket-milling is typically 6-10 times, or more,
expensive than Dream's technology and it tends to leave mass
concentrations at the node of ribs.
Dream specializes in the design,
engineering and in-house
production of bubble-free
lightweight mirrors using modern 3D CAD, FEM/FEA, CNC
equipment and micro-processor controlled furnaces & annealing
ovens. Dream provides industry-leading convex, concave and plano
mirrors that eliminate the mechanical & thermal performance
losses associated with solid mirrors, which is currently a 350
year old technology. The
CTE of Dream's lightweight mirrors is 3.16x10-6/°K. Dream
does not use plate glass, which has a CTE almost
3x higher (9.1x10-6/°K) and is nearly 4x more sensitive (when
comparing the same thicknesses) to bending due to thermal transients;
internal temperature gradients warping the figure of the optical
surface. Due to the thin features of Dream's zeroDELTA mirrors,
not support internal temperature gradients.