What is modular instrumentation, anyway?

Lots of nebulous terms frequently used in the optoelectronics industry mean little or nothing to the uninitiated (or are ambiguous to the rest)—integrated modules, dynamically reconfigurable subsystems, self-provisioning platforms—and how about the ubiquitous service solutions? Add your favorite, or mix and match terms, like accessory unit, functionality, and high-end application with near-meaningless descriptors like state-of-the-art, rugged, optimal, or high-performance. After choosing the topic of modular instrumentation for this supplement, several industry veterans asked, rightly enough, "What do you mean by modular instrumentation, anyway?" That's a good question.

Modular instrumentation, a term so commonly heard and touted by companies that offer it, can mean slightly different things depending on whom you ask. There is, however, a common implied definition. Instrumentation is equipment used to test, characterize, or monitor properties of something, like the surface roughness of a substrate, or the amplitude of a signal through a fiber.

Modular can refer to something constructed with standardized dimensions for flexibility and a variety of uses. Modular can also refer to a module, which obfuscates its meaning because "module" has several definitions. Module can simply refer to "a unit for use with other units." Sometimes, instrumentation is called modular by virtue of its portability to different sites, or by virtue of its ability to perform multiple tests. In its most common meaning, however, module refers to a packaged functional assembly of components for use with other such assemblies.

In the first of three articles in this supplement, Armando Valim of National Instruments (Austin, TX) introduces modular automation as a combination of four crucial disciplines: motion, vision, optical, and electrical instrumentation. Successful automation, Valim explains, must incorporate each of these disciplines in one package. The second article, by Michael Serry of Digital Instruments, Veeco Metrology Group (Santa Barbara, CA), gives a specific example of modular instrumentation in the atomic-force microscope (AFM). Commercial AFMs offer numerous accessories that enable the use of a single instrument in a plethora of applications. Finally, John Perlick of Wavecrest (Eden Prairie, MN) discusses the advantages of modular test equipment in optical networks. The diversity of protocols in optical networking requires a versatile testing approach.