'Top-down' optical design and advances in the manufacture of precision optics combine to optimize fiber optic illumination and projection displays.
Karlheinz Strobl and Michael Thomas
Product advances based on classical illumination technology have primarily correlated with advances in lamp technologies: higher brightness, shorter arc and/ or higher pressure. But rethinking the design of an illumination system can advance the state of the art independent of lamp development: Many small improvements in optical efficiency can add up to considerable increases in performance.
Optical designers know that aspherical components and nonstandard manufacturing technologies can improve the performance, weight and size of an imaging system. For illumination systems (e.g., projection displays and fiber optic lighting), the electrical-to-optical conversion efficiency relates directly to the minimum size, weight and cost requirements of the power supply and therefore to the product's overall price/performance ratio.
Designers will find optimum optical designs through a "top-down" rather than a "bottom-up" approach. Such inverted approaches derive design constraints from product specifications and combine components to best fit those constraints.
Market pressures have not justified the required investments by component manufacturers. However, recent growth has resulted in near-term potential for annual sales of more than 1 million projection display systems -- and in increased interest in claiming a portion of that market.
In many of today's illumination design challenges, an optical system designer often has to accept one or more optical elements that cannot be controlled or changed but that, if left uncorrected, can deteriorate system performance.
A common and often-ignored example of such a case is the transparent envelope of a short-arc, high-pressure mercury lamp. To withstand the high gas pressure, this type of lamp is typically manufactured to high tolerances, so its resulting envelope shape is quite consistent and reasonably correctable. . . .