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| Wollaston's Contributions to Optics |
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In 1802 Wollaston developed the refractometer, an instrument for determining refractive indices with the aid of total reflection. The reflection goniometer for the measurement of reflecting surfaces followed in 1809. As a crystal goniometer, it is used to measure angles on crystals. – The theodolite goniometer, a crystal goniometer with two graduated circles, one arranged at right angles on top of the other, allows angular measurements in one section and on all surfaces with the exception of the cemented surface without having to move the crystal.
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| Crystal refractometer for jewelers from Carl Zeiss, ca. 1940. | Advertisement for Zeiss Punktal®, ca. 1920. |
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| Research microscope Axioplan® with device for drawing microscopic images. | Wollaston polarizing prism |
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Around 1804 Wollaston established that visual acuity decreases when the wearer looks through the peripheral areas of biconvex eyeglass lenses. At the same time, he noticed that meniscus-shaped eyeglass lenses provided higher quality vision. Many ophthalmologists – including Ostwald and Tscherning – were looking for improvements, but their attempts were of little significance for practical use. – It was not until 1908 that Moritz von Rohr succeeded in exactly computing an eyeglass lens with what is known as point focal imagery. It remains in the Carl Zeiss product line to this very day: Punktal®.
In 1804, quite independently of Joseph von Fraunhofer, Wollaston discovered the absorption lines in the solar spectrum which are still used for determining chemical elements by spectral analysis to this very day. He improved the microscope and in 1807 developed the camera lucida, an optical apparatus used for drawing the outlines of objects.
In 1820 he invented what has come to be known as the Wollaston prism. It is a polarizing prism consisting of two calcite components cemented such that they deviate the two emerging beams (which are mutually perpendicularly polarized) by nearly equal amounts in opposite directions.
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