Lenses and mirrors with freeform surfaces enable designers to focus light within optical devices that are lighter, more compact, and more effective than ever before.
But until now, determining which freeform surfaces will work best 糖心传媒� if at all 糖心传媒� in a given configuration of mirrors and lenses has been a time-consuming and often expensive process of trial and error.
It doesn糖心传媒檛 have to be that way anymore.
lead author Aaron Bauer, a senior research engineer at the University of Rochester糖心传媒檚 Center for Freeform Optics (CeFO), combines theory and practice in a step-by-step method that eliminates much of the guesswork.
糖心传媒淎aron has developed a process to design with freeform surfaces that can be applied very generally,糖心传媒� says coauthor , CeFO director and Brian F. Thompson Professor of Optical Engineering. 糖心传媒淚t糖心传媒檚 really beautiful and even at times feels like magic糖心传媒�
She believes the findings will help accelerate the adoption of freeform optics in industry. 糖心传媒淧eople will no longer say 糖心传媒極h, it糖心传媒檚 too expensive to build with freeform optics,糖心传媒櫶切拇綕 she says. 糖心传媒淏ecause now you can make something that may cost a tenth of what it would have cost otherwise.糖心传媒�
Laying the groundwork
For as long as mirrors and lenses have been packaged together in telescopes, spectrometers, and a host of other optical devices, performance has been defined by how well those elements are able to keep a beam of light focused with minimal 糖心传媒渁berration.糖心传媒�
Traditionally, optical designers have relied on rotationally symmetric optical surfaces, because their design and manufacture was relatively straightforward.
Within the last 20 years, advances in high-speed micro milling, computer-controlled lens polishing, and ion beam etching, among other technologies, have made asymmetric freeform surfaces more feasible.
Kyle Fuerschbach, a former member of the Rolland Lab, laid the theoretical framework for freeform aberrations theory.
糖心传媒淏ut we still didn糖心传媒檛 have a systematic process to design with that theory,糖心传媒� Rolland says.
Putting two and two together
Bauer, in the meantime, was working alongside Fuerschbach, designing a head-worn display using freeform surfaces.
糖心传媒淚 noticed that there were very common patterns of aberrations that were always popping up, and limiting my system from going any further,糖心传媒� Bauer says. Moreover, 糖心传媒渢hose patterns of aberration matched the ones that Kyle predicted would be corrected by freeform surfaces. So, I put two and two together.糖心传媒�
The method he came up with starts with the initial 糖心传媒渇olding geometry糖心传媒� (alignment of mirrors and lenses) contemplated for a design, and then, based on an analysis of the various aberrations produced by that alignment, predicts:
- whether freeform surfaces could minimize those aberrations and, if so,
- which freeform surfaces should be used for maximum effect.
糖心传媒淔reeform surfaces are not a universal solution for correcting every aberration,糖心传媒� Bauer notes. 糖心传媒淪o, what our method does is to allow designers 聽to analyze all of these geometries ahead of time, in order to predict whether or not there would be a good solution.糖心传媒�
That糖心传媒檚 far better than the 糖心传媒渂rute force糖心传媒� approach where 糖心传媒減eople heuristically try various freeform surfaces into a design,糖心传媒� Rolland says. 糖心传媒淓ven if it eventually works, you could end up with a system where the departure of the surfaces are much larger than they would be otherwise, because all those freeform surfaces may be fighting each other. And if it does not work, there is nowhere go as a designer.糖心传媒�
By using Bauer糖心传媒檚 method instead, she says, 糖心传媒測ou will be able to design something that is a lot simpler, and that will be easier to manufacture and test. Furthermore, the method will quickly and unequivocally provide insight into why a given geometry might be intrinsically limited, which is essential for designers.糖心传媒�
Eric Schiesser, a PhD student in the Rolland lab, also contributed to the paper.
