Compact fiber-optic detector-array-based spectrometers pioneered by H.-E. Korth of IBM Germany and popularized most notably by Ocean Optics, Inc. have found widespread use in a multitude of applications. For example, see “A Computer Integrated Spectrophotometer for Film Thickness Monitoring,” H.-E. Korth, IBM Germany, JOURNAL DE PHYSIQUE, Colloque CIO, Supplement Number 12, Tome M, December 1983, pg. C10-101. Because the purpose of a spectrometer is to measure the intensity of light as a function of wavelength, the accuracy of a spectrometer's wavelength calibration is of primary importance. Accurate wavelength calibration relies on consistent mechanical alignment of the spectrometer's several optical components. Alignment of these optical components can be changed by ambient conditions (especially temperature) and by mechanical shock. Typically spectrometer calibration is performed once during manufacture followed in some cases by periodic re-calibration in a laboratory setting. Given the precision required of these devices maintaining sufficient wavelength calibration in the field can be a challenge, especially in portable equipment. In general the only effort by spectrometer manufacturers to actively maintain wavelength calibration is to monitor and adjust for temperature effects based on stored empirical data. Any other significant change to spectrometer calibration in the field is not corrected for and is generally not even detected, which can lead to important undetected errors in their use.