SWaP Reduction Use Case Video Tutorial
https://www.youtube.com/watch?v=90VqWleGIOo
SWaP Reduction is the reduction of size, weight and power for a device. Ironically, SWaP Reduction is also SWAPping out two or more lenses for one of equal or better performance.
In many applications, we also seek greater power output through SWaP Reduction. In optical lens design, we often replace the concept of power with greater clarity. Alternatively, we think in terms of reduced aberrations.
Your SWaP Reduction will be based on optimization of spot size or wavefront error. We have found the best results for most optical lens systems by optimizing on spot size.
Our reTORT ray tracing software is ideal for SWaP Reduction due to its native GRIN and Metalens capability. It’s all built in and ready to use.
About the Video Tutorial
One of our engineers will step you through the process. This video is available on our YouTube channel. Please visit and subscribe to our channel. We plan to bring you more interesting videos.
Ray Tracing Software Video Tutorial for Optical Lens Design
To start, we designed an achromatic triplet. The design parameters of this triplet are shown in the video.
This triplet will form the basis of our SWaP reduction exercise. Our objective is to reduce size and weight using a gradient index lens.
We usually use a gradient index lens when size and weight reduction is our objective. Contrary to that, Metasurfaces are our are go to technology for performance enhancement and special effects.
You will notice, as you watch the video, that our engineer deliberately starts with a GRIN profile he knows will not focus. The engineer then adjusts to polynomial coefficients that he knows from experience are better assumptions.
This is done to mimic the typical iterative process of the typical optical lens design workflow. But this is why we use a state-of-the-art ray tracer like reTORT. You can perform optimizations in seconds and get a feel for the best direction for your own design objectives.
This particular tutorial uses our version of the well-known Damped Least Squares local optimization. Our reTORT ray tracer offers local and global optimizers.
Optical Lens Design Optimizers in the reTORT Ray Tracing Software
Lens system optimization is the ultimate goal in any design. To this end, reTORT offers wizards for fast setups. In this way, with a single click, you select built-in optimization goal selections.
reTORT ray tracer uses two different approaches to optimization. This aids in reaching your objective and matching your desired workflow. These two approaches are a local gradient based method and a global optimization method.
Local optimization uses the traditional damped least squares algorithm. Our local optimization uses finite differencing to determine the gradients of each optimized lens parameter. These parameters may include lens curvature, thickness, air gap or a GRIN lens property. Then, the optimizer exports the gradients to the damped least squares optimizer.
Our global optimization is based on a genetic algorithm. We use the covariance matrix adaptation evolution strategy. But let’s just call this CMAES from now on, okay?
CMAES uses an evolutionary strategy to fully explore the problem space. Hence, it is truly global. It will find a global minimum during optimization. Therefore, it does not get stuck in a local minima.
This article on evolution strategies gives a plain language explanation. It includes a section on CMAES. This source often uses cute graphics to explain it’s point. You can see a visual of getting stuck in a local minima right here.
Back to the Video Tutorial
I’m sure you’ve been following the video. So, you have a good idea of the process. The second try resulted in the rays focusing on the focal plane. We used the option to only show the meridonal rays to get a clearer view. See the result below.
And you can now look at the focal drift plot to see we not only increased performance but we also decreased size and weight. Very simple. I hope you followed along and stay tuned for more from E x H.
The above images show that the benefits of using GRIN lenses is very clear. And the reTORT Ray Tracer makes this design objective easy to implement.
Don’t Forget About Metalenses for Special Purpose Lense Systems
This example focued on Gradient Index lenses for SWaP reduction. Metalenses are useful in the simplification of complex optical systems. Take a look at our YouTube Tutorial on Metalenses.
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About E x H, Inc.
Our mission is to provide you with advanced simulation tools. These tools allow you to design optical and RF systems that are smaller, lighter, faster and have greater clarity than ever before.
We license some of our solvers from Penn State University. PSU’s world reknowned Computational Electromagnetics and Antennas Research Laboratory. have developed these solvers.
Many of our scientists and engineers have been educated at CEARL.
We have also participated on multiple programs funded by DARPA as well as other sectors of the Department of Defense.
On the business side, we have been backed by Gran Sasso Ventures, the same venture capitalists that funded collaboration software firm Compoze Software, now a part of Oracle [ORCL:NYSE], and multitouch technology inventor FingerWorks, the driver of touch screen technology and now a part of Apple [AAPL:NASDAQ].
E x H is at the forefront of transformation optics.
