Navigating the optimization and tolerancing wizards
Start by navigating to the optimization wizard icon. Open the optimization wizard. Most choices will be pre-loaded. The default settings are typically acceptable for most designs. The first tab contains the optimizer settings.
The goals are set on the next tab.
The parameters in the third tab were pulled automatically from the Lens Stack, Bounded Elements and other objects. Minimum and Maximum bounds have been specified. These bounds are usually applicable to most types of design problems. First, review them. Or run an optimization first and inspect the results before changing them. Optimizations are so fast in reTORT, an initial run can provide a better idea of a good starting point.
Global versus local or both
E x H offers a variety of optimization methods. Access all of the methods from the model hierarchy dock. The most powerful of these are accessible with only a few steps in the optimization wizard.
Global optimization is based on the CMAES evolutionary algorithm. This is the most powerful optimizer and the go to optimizer in any E x H project. It is run within bounds. If bounds are exceeded, the program will tell you in the status dock. This status message will also tell you where the bounds are being exceeded. Easily make adjustments with this information.
Always run CMAES with bounds enforced. It will run fast and more efficiently. The best method is an iterative one where you start optimizing the most critical aspects of your design. Then you add other parameters incrementally. This allows the opportunity to make adjustments.
The local optimizer is the E x H implementation of DLS. It is also powerful. But, the wisest approach is to use CMAES and DLS cooperatively as opposed to the exclusion of one or the other.
DLS is great as a starting point when you need to determine starting values. For example, to determine the starting polynomial coefficients for an asphere. DLS is also valuable when you are exceeding bounds. Values to correct are highlighted in a very graphical way. Run DLS without enforcing bounds for this reason. Bounds and current parameter value that are out of range will be highlighted in the parameter tab of the optimization wizard.
Reconsider the bounds and make adjustments before re-running CMAES.
The Tolerancing Wizard
Now, open the tolerancing wizard and see what happens. The first action is that the typical AutoTolerance parameters were estimated and populated in the parameters dock.
The choices are Monte Carlo, sensitivity analysis or both, with or without compensators. Open the settings tab first. The default values are added automatically and will likely be very appropriate for the analysis.
Now open the parameters tab. Select which parameters to deviate for the tolerancing analysis. Or, select others as compensators which will be modified to maintain the original performance. Others can remain fixed. In the image, two parameters are chosen to deviate and two as compensators. The distribution of each parameter is also chosen. The choices are normal distribution, truncated gaussian, uniform or top-hat, and end-loaded.
Wizards offer a new level of ease in ray tracing. Optimization, tolerancing and plotting wizards in the reTORT ray tracer give total flexibility, fast input, and make better use of the designers precious time.
Useful tips in using reTORT/GEMSIF
Please see the last section of our feature list.
1. Always pay attention to the status bar, It will warn you of problem situations and save you valuable time
2. Save interim satisfactory designs with descriptive names, You can always come back to that branch of your work and take it in a different direction
3. When you cannot find a function, follow the Model Hierarchy, it follows a typical analysis, starting with the Optical Source and ending with Results and Views
4. When you cannot find a property, click on the Model Hierarchy among the functions in which you’re interested and then scan the Property Editor window that opens, you’ll soon learn where to quickly find every bit of design data
5. Make use of the Parameters Dock to leverage your time by defining additional parameters that can be used by multiple functions
6. When you have questions in reTORT and GEMSIF, always click on the function in which you’re interested. Look to the documentation dock in the lower right for further definition. Usually, you’re curiosity will be satisfied by the first paragraph you see.
7. Delays in optimization are usually due to the solution space going outside of the optimization bounds. In some cases, this can happen many times. Watch the status dock. A message will appear with notice that the solution is exceeding bounds, where that is occurring and what the values are.
About E x H
E x H’s mission is to provide you with advanced optical system simulation tools. The result is tools that allow you to design optical systems that are smaller, lighter and faster. Watch our SWaP reduction use case tutorial for a taste of this.
Some of our solvers are licensed from Penn State University. PSU is one of the leading research institutions in the USA.
We have participated on multiple programs funded by DARPA that have allowed us to develop software on the leading edge of technology.
Outside of the optical space, this same reTORT Ray Tracer was used to fast prototype the transformational optics that proved the concept for Isotropic Systems’ high throughput, multi-beam satellite terminals (https://www.isotropicsystems.com/).
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.
