This article is the last of our three-part series on optical design secrets. In previous blogs we explained some important aspects of optical manufacturing, and we offered advice on how to protect your production schedule by using reliable optics sourcing to defend your optics supply chain. This final article provides some best practices to follow when using optical design software. There are too many programs and applications for us to give software-specific advice, but our optical design expertise enables us to provide some important principles that apply whenever you use software to optimize the performance of an optical system design.

Focus on Overall System Performance

Optical system design relies on the complicated interoperation of several component parameters such as lens curvatures and thicknesses, optical coatings, and aperture radii. Changing parameters on one component inevitably alters the tolerances on another. It is easy to get caught in a never-ending loop of bouncing constricting tolerances among the optical components. Remember that it is not the performance of the parts that matter—it is the performance of the system. Rather than setting rigid restrictions on the performance of each lens, optimize the entire system. It is often useful to loosen the tolerances on the individual components and leave one parameter, such as an interoptic lens or a tilt, to be adjustable. That parameter can then be adjusted during assembly to optimize optical performance.

Use a Starting-Point Design

There is no reason to start an optical design from scratch, especially if you are designing a complicated optical system. Even Isaac Newton, who literally wrote the book on optics (or rather Opticks), is famous for saying, "If I have seen further it is by standing on the shoulders of Giants." Ray tracing programs are full of example systems. (For example, see Zemax's Zebase.) Find something that is similar in concept or function and start from there. Researching existing optical design prevents you from wasting your time reinventing something that already exists, it gives you ideas on methods of improvement, and it saves you a lot of typing!

Factor in the Application Environment

In optical design software, the optics float in space, perfectly aligned, but the reality is that all of those components must be mounted within a structure, and that enclosure is surrounded by a universe over which we have very little control. As examples, materials may sag because of gravity, contract and stretch in the heat, loosen because of vibration, shatter in the cold, or discolor because of radiation. For good optics design, it is vital to understand, before setting tolerances, where an optical system will be used and how the environment affects those materials.

Optimize for Cost As Well As Performance

Software is a powerful tool for optimizing optical designs to match the required optical performance metrics, but optimizing for cost is incredibly difficult because there are a considerable number of variables. Some aspects of cost optimization have become easier because many optical suppliers (like Ross!) have included their catalogs into the design software, making it simple to compare component costs. However, the price of the individual components is not the only significant factor affecting system cost. You must also consider issues such as material availability, assembly costs, and lead times, to name only a few. Determining all of those factors seems impossible, right? It is impossible! No optical design software can do that, but there is one thing that you can do that optical design software can't:

ASK SOMEONE!

If we compress this entire series into a single message it is this:

• Know what you don't know.
• Know whom to ask.

Those two skills set great designers apart from good designers. Great designers devote time to asking questions before they sit down to start designing. You can avoid false starts and wrong turns by verifying, up front, things such as the availability of materials or the operating environment. Time spent gathering information at the beginning of a project saves money at the end.

Are you facing a challenging optical design? Ross Optical is not a typical catalog optical supplier—we possess the optical design expertise to help our customers develop unique optical systems that may require hard-to-find optics or specialized assembly. Give us a call to talk to one of our engineers about how Ross can help you develop the best performing system at a cost that falls within your budget and within a time frame that matches your schedule.

Download our tip sheet with ten practical considerations to keep in mind when designing optical systems, from your initial concept through final assembly. Download the tip sheet to learn more: