The increasing use of aspheres in a variety of optical systems has pushed the industry to become more efficient at its manufacturing processes. Non-optimized grinding techniques can cause excessive sub-surface damage and mid-spatial frequency errors which can be both time consuming and difficult to remove during polishing. The SCGa 100 grinder and SCPa 100 polisher provide unique platforms for asphere manufacturing. The SCGa 100 uses optimized kinematics to create a stiff and rigid platform which minimizes grinding errors and artifacts. Subsequently, polishing time on the SCPa 100 is decreased reducing the risk of altering the aspheric shape. This process improves surface quality while simplifying manufacturing.
Innovative freeform optical systems such as head-up displays or LED headlights often require high quality and high volume optics. Injection molded polymer optics offer a cost effective solution. However, mold manufacturing for this process is extremely challenging as the machining of freeform surfaces is currently characterized by several independent production steps which can limit surface accuracy. By integrating diamond turning, milling, and metrology onto a single platform, the UPC 400 improves surface accuracy. Advanced software for machining and measurement data further reduces surface inaccuracies. This combination makes the UPC 400 efficient for prototyping free-form optics and manufacturing high precision molds.
The design and manufacture of most optical systems revolves around the use of ideal optical surfaces. "Perfect" spheres
or flats are optimally combined and toleranced during the design phase, and the manufacturers attempt to get as close as
possible to these perfect optical surfaces during fabrication. One reason for this stems from the inherent capabilities of
the industry's oldest and most pervasive polishing tool: the full-aperture lap. The shape and motion of these tools
naturally produce spherical or flat geometries. More recently, a number of new manufacturing technologies based on
sub-aperture polishing tools have become available. Sub-aperture tools enable local, preferential removal: a controlled
way to polish more material at some locations and less at others. Magnetorheological Finishing (MRF(R) ) is one such
sup-aperture polishing technology, and when combined with an accurate measurement, can offer a precise method for
converging to the perfect surface: local removal based directly on measured surface height. This capability, however,
can also be leveraged in other, more creative, ways. For example, by replacing the typical surface-error measurement by
a transmitted wavefront measurement of an entire low-field optical system, a hitmap can be created for one surface in the
system that will perfectly compensate for errors of all the other surfaces. This paper will explore a number of examples
where "perfectly bad" surfaces have been exploited in actual optical systems to improve performance, improve
manufacturability, or reduce cost. In addition, we will ask the question: if making a "perfectly bad" surface was as easy
as making a perfectly good one, would this capability be used more widely by the precision optics industry?