Geometrical Optics
Geometrical optics basically means ray optics. The design task is usually to design and arrange lenses, mirrors, and prisms into systems that perform some specified imaging (or illumination) function with specified characteristics. Details that must be considered in a geometrical optics design include stops, pupils, and aberrations. An understanding of the characteristics of available optical materials is important, as is familiarity with manufacturing techniques and capabilities.
It seems to be a common phenomena that geometrical optics is thought of as consisting primarily of “lens design”. While it is sometimes necessary that special-purpose lenses have to be designed to meet particular needs, (and I have done this), I have found that many of my clients' most important problems in geometrical optics are not primarily lens design problems. I have been able to save clients much trouble simply by making sure that images are in the right place, are the right size, and are oriented correctly. In other cases, simply moving the stop in a system has solved the client's imaging problem. I have seen more than one project where a “lens design” emphasis has led to failure, either because the lens designer was not made aware of, or did not understand, the critical system level issues that existed.
For an example of a novel imaging system which is intimately connected to lens design, but which could not have been developed by thinking only in standard lens design terms, see my STABL-M™ focusing system.
Many years ago one of my teachers stated that, in his experience, the most common errors made by non-experts in optics had to do with illumination in images. In my experience since then, I have also found this to be the one single thing that causes clients the most trouble. It is very often the case that a client expects to get more light at an image or at a detection plane than is physically possible, given the other constraints on his system. Needless to say, this causes much difficulty which can be avoided if the appropriate expertise is brought to bear early in a project.
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Copyright © 2002, David F. Schaack. All Rights Reserved. |