This article is the last of our three-part series on optical design secrets. In previous
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
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
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