Barry R. Masters
UO>ADRs} NZ7g}+GTG Last year marked the 100th anniversary of the death of Ernst Abbe, who passed away on January 14, 1906—just a few days short of his 65th birthday. Abbe is well known for his seminal contributions to scientific microscope construction, which include his diffraction theory for image formation, and the formulation of the sine condition and Abbe number. He was also a noted entrepreneur, astronomer and social reformer.
Jc95Ki1X vdV@G`)HPr #3leM Z 6 Ernst Abbe was born in Eisenach, Germany, on January 23, 1840. He spent his childhood in poverty—which perhaps explains why he was committed to social welfare for the rest of his life. After graduating from secondary school, he began his studies at the University of Jena. There, Abbe attended lectures in mathematics and physics.
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pO[ @2tF rLtB^?A z Early on, his professors noted his acumen in science. Abbe won a scientific competition in his third semester and, later, he was awarded a scholarship by city officials at Eisenach. After completing two years at Jena, Abbe took up three additional years of studies at the University of Göttingen, where he attended lectures in mathematics given by Bernhard Reimann, as well as lectures in meterology, optics and astronomy.
9t9x&.A N[:;f^bH49 zuwlVn At Göttingen, Abbe studied the theory and practice of precision measurements (i.e., the assessment of extremely weak electric currents and magnetic fields) as well as the design and construction of measuring instruments and the theory of experimental error.
;N#d'E\ kZfa8w L]P \9N1: Abbe remained in Göttingen for his doctoral research under the supervision of two professors: Wilhelm Eduard Weber and Karl Snell. His doctoral thesis focused on experimental substantiation of the theorem of the mechanical equivalence between heat and mechanical energy. He received his doctoral degree in 1861. One year later, he submitted research on the laws of the distribution of errors in an observation series to the philosophy faculty at the University of Jena for his Habilitation paper (a German post-doctoral requirement for teaching as a professor at a university).
=Q>'?w> [ > Q+=(l A\X?Aq-^' Over the next 10 years, Abbe published several scientific papers and was subsequently appointed as a lecturer of astronomy in 1877 at the University of Jena. In addition, Abbe was made the director of the observatory at the University of Jena (1877-1900).
nkUSd}a`r {26 /SY ~bC{ R&p In 1866, Abbe met Carl Zeiss, who proposed that Abbe establish a scientific foundation for the manufacture of optical microscopes. Zeiss had begun his production of single-lens dissecting microscopes in Jena in 1847 after Matthias Schleiden—a German botanist and co-founder of the cell theory—suggested that he get into that line of business.
h\k@7wgu O`<id+rx `7 [z% cuK Using lenses purchased from other manufacturers, Zeiss had fabricated in 1857 the first compound microscope consisting of a microscope objective and an ocular. At that time, lenses were ground and combinations were tested for their optical performance; there was no scientific basis for the design of high quality lenses. The historical method of lens grinding, testing and selection was about to change.
tJ;< =.n xM"k qRZ CY "& @v1 The 26-year-old Abbe started work for Carl Zeiss as an independent contractor. Over the next few years, Abbe developed several precision optical instruments to measure the shape and optical constants of lenses. Abbe’s focometer measured the focal lengths of lens elements, lens combinations or a complete optical system. The Abbe refractometer measured the refractive index of glasses or liquids based on the angle of total reflection. The Abbe spectrometer measured the refractive index and dispersion of various glasses. In 1870, Abbe developed his apertometer, which measured the numerical aperture of microscope objectives.
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