A portrait of Joseph von Fraunhofer.About 20 years ago, my wife and I were driving through Bavaria in Germany when we happened upon the small town of Benediktbeuern, the site of a campus-like monastery with a huge beautiful baroque church, which we decided to visit. In the grounds, we noticed a sign pointing to a ‘Glashüette’ and, being interested in materials and art, we ventured over to the glass shop and were surprised to witness a very enjoyable tour of the laboratory and factory of Joseph von Fraunhofer. In this building, which houses three large glass-melting furnaces, Fraunhofer achieved his remarkable and famous contributions to both the science and practice of optics. But his route to success was neither easy nor traditional.
Fraunhofer was born in 1787, the tenth and last child of a poor glass grinder, who was unable to provide him with any education. Orphaned at the age of 11, Fraunhofer was made an apprentice (without pay for six years) to a stern lens grinder and mirror maker who would not even permit him to read or study. In 1801, the house where he worked collapsed, killing the proprietor and trapping the boy for several hours in the rubble. This ‘fortunate’ accident brought the poor orphan to the attention of the politician Joseph von Utzschneider and thereby to Prince Max Joseph, who provided him with books on mathematics and optics, as well as enough money to purchase his own glass cutting and polishing rig. With some instruction from the Benedictine monks, Fraunhofer outfitted the Glashüette for developing improved methods for preparing optical glass, grinding and polishing lenses, and testing them.
From the technical standpoint, Fraunhofer analyzed lens making, studied the effects of glass composition, flaws, and heat treatment on optical properties, developed new grinding techniques, and converted glass polishing into a manufacturing operation. He invented and developed the moving and measuring devices used in astronomical telescopes. He developed a cement to assemble lenses and invented a test device to check the shape and concentricity of lens surfaces. A Fraunhofer telescope was used to discover the planet Neptune. His work led immediately to a German dominance in optical products: telescopes, binoculars, microscopes, magnifying glasses, and cameras.
But Fraunhofer mixed his engineering expertise with scientific inquiry. He accurately determined the refractive indices of optical glasses required for the design of achromatic objective lenses in telescopes. Upon examining the spectrum of solar light passing through a thin slit, he noticed a multitude of dark lines. Realizing that these lines could be used as wavelength standards, he accurately measured 324 lines from the solar spectrum and labeled the most prominent lines with letters, a nomenclature that survives today. The atomic absorption lines, as explained later by Kirchhoff and Bunsen, are still called ‘Fraunhofer lines’. Fraunhofer also built the first diffraction grating, and used it to measure the wavelengths of specific colors and dark lines of the solar spectrum. Thus, the experiments of Fraunhofer laid the groundwork for spectroscopy, diffraction, quantum mechanics, and arguably contributed to the widespread modern optical methods for data transmission and storage.
Because both his technical and scientific contributions were immediately recognized, Fraunhofer received many honors and awards. He became a member of the Bavarian Academy of Sciences, received an honorary doctorate, was named a professor of physics at the University of Bavaria, and was knighted (explaining the earned, not inherited, ‘von’). Presumably, when asked to lecture on physics at the university, Fraunhofer replied that he didn't know how to lecture, having never heard one. Unfortunately, Fraunhofer died of tuberculosis at the very young age of 39, perhaps contracted or aggravated by the inhalation of heavy metal vapors around the glass-melting furnaces.
The fields of science and engineering surely offer many examples of exceptional achievement from those with little or unusual backgrounds and education (for example Newton and Maxwell). But assuredly, Fraunhofer's experiences can offer encouragement and hope to those of us lacking or failing in some elemental, traditional aspect of our own development and education. Fraunhofer's career also illustrates the opportunity for an effective synergy between science and engineering. For anyone involved with optics or the history of science, I would recommend a visit to the Glashüette in Benediktbeuern.