Freeform Optics

Freeform optics has revolutionized optical system design, advanced fabrication and testing techniques enable new and compact system forms to be developed. We will focus on design, fabrication, and testing of small scale freeform optics (smaller than 300 mm diameter).

In the past few years, we have established the diamond turning fabrication and testing facility (Nanotech 350FG and Zygo Newview8300) with the funding from the College of Optical Sciences, TRIF, and NIH. The goals of this facility include (1) establish the freeform optics research program at UA, (2) support the research activities across UA campus, and (3) support the education activities. With glass press molding machine 140GPM which will be added in 2016, we will be better to support freeform optics research.

While the current optical design software is powerful enough to design complex optical systems, there is still a strong need of new design methods to establish the initial configurations of new optical systems. Our research will focus on (1) more efficient design methods for LED illumination and laser beam shaping and (2) design methods of freeform optics for imaging applications. We have developed new design methods of freeform optics for LED illumination and laser beam shaping.

The other two challenges in freeform optics are fabrication and testing. We have made good progresses in modeling the surface quality under the real working environment and tolerancing optical systems with freeform surfaces. Currently the challenges in diamond turning fabrication method include the tool alignment and the lack of in situ metrology. The tool alignment is a very time consuming process, any error in tool alignment will impact the surface finish and form. One of our goals in freeform optics fabrication is to develop in situ metrology for tool alignment and testing of the fabricated element before it is removed from the vacuum chuck. In situ metrology will have a huge impact on the freeform optics fabrication, improving the productivity and fabrication precision. Off-line metrology of freeform optics is another challenge. Current interferometric methods and contact type of surface profilers have some limitations in measuring freeform optics, such as dynamic range and measurement speed. We are developing deflectometry technique with larger dynamic range, potentially suitable for in situ and off-line metrology.

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