At home, under my kitchen sink, are two screwdrivers, a hammer, and a box of nails. In my basement, however, are three jam-packed toolboxes, a table covered with a further assortment of hand tools, and a dozen or so power tools. So where do I go when something in my house ceases to function? The kitchen sink, of course. Inevitably, though, I end up in the basement, where I can put my hands on the right tool for the job.
When faced with a need for a spectroscopic tool, optoelectronic engineers and scientists are lucky to have a large selection of high-quality spectrometers commercially available. But finding the right equipment may require more work than doing a quick search on the Web (a place even less tidy than under my kitchen sink). Most important is that the desired tool should be carefully matched with its application. While this task can sometimes be accomplished by one person, more often crucial information comes from others: a lab or field technician, a staff scientist, a production engineer, a customer. The optimal setup may end up being stock equipment, a custom-designed item, or an instrument still under development in a lab. But the extra effort needed to find the right tool for the job rarely goes unrewarded.
The first article in this Optoelectronics World concerns an application that is of global importance: measuring the concentration of carbon dioxide in the atmosphere. Here, Barbara Paldus and colleagues describe the use of cavity-ring-down spectroscopy, which has several benefits over traditional spectroscopic techniques for measuring carbon dioxide, including true absolute measurement capability.
Process control in the pharmaceutical industry relies on spectroscopy, which has traditionally been done with conventional large spectrometers. In the second article, Richard Crocombe describes the use of optical channel monitors-ultrastable miniature spectrometers developed for the telecommunications industry-for identifying and measuring the components going into a pharmaceutical product.
In the last article, Hector Lara and Ron Hartmayer start with a specific manufacturing step in the semiconductor industry-deposition of cobalt tungsten phosphide barrier caps in miniaturized copper interconnects-and describe the development of spectrometer types in which the same internal workings are designed into different exterior forms, one for versatile diagnostic use and another for integration into the deposition equipment itself.
