Microscope achromatique par Charles Chevalier, 1832
Achromatic microscope by Charles Louis Chevalier (1804-1859), between 1832 and 1851, which was the period he occupied the address which is engraved on the microscope. Many features in it indicate a very early date of this sequence. It is signed "Microscope achromatique / perfectionné par / Charles Chevalier / Ingénieur Opticien breveté / 163 Palais-Royal / à Paris". Total height is between 45 and 55 cm. The optical tube, complete with its flat-shaped plug and simple pull, consists of an eyepiece with two plano-convex lenses (180 and 260 mm) measuring 600 mm in height and a lens formed by two doublets. The tube is screwed on a reclining rectangular angled arm on which the stage is mounted (adjustable by a rack whose wheel is of ivory as in the early production of Chevalier) and a large concave mirror (perhaps renewed). Finally, everything is attached to a cylindrical column with folding tripod foot. The illumination prism that appeared in the first form of Selligue-type achromatic microscopes is here replaced by a simple bull's eye lens held by a ring to the objective. Also present, on the plate, are two clamps to hold the preparations of transparent objects and, under the plate, the variable diaphragm type The Baillif. This early model of a secondary form, post-Selligue, was called "perfected" achromatic microscope by the best French manufacturer of microscopy of the first half of the nineteenth century, Charles Chevalier. It probably dates to slightly before 1840.
Charles Louis Chevalier (born Paris, Apr 19th 1804, died Paris, Nov 2th 1859) was an optician and instrument maker. He was son of the optician Vincent Jacques Louis Chevalier who himself was son of an optician, Louis Vincent Chevalier who had founded the family's company in Paris in 1765. The company of Vincent and Charles Chevalier was famous for the achromatic lenses which were invented by father Vincent, and the lens/prism optics they both had invented for camera obscuras. In 1825, the cousin of Nicéphore Niépce came to the Chevaliers to buy achromatic lenses for his experimental cameras. He told the Chevaliers about his cousin's first efforts to achieve persisting photographs. That was when Louis Jacques Mandé Daguerre just got interested in similar experiments. Later Chevalier gave him the address of Niépce, the first step for Daguerre to become a photography inventor himself. In 1832 Charles founded his own company.
Chevalier was one of the first to use multiple lenses screwed together to achieve higher magnifying power, but chromatic aberration, which had plagued the users of microscopes since their beginnings, was still a problem with the lens combination. In 1830 Chevalier, with the help of another French microscope maker, M. Selligue, started to make horizontal microscopes, after a design shown to him in 1827 by Giovanni Amici, an Italian instrument maker. Charles Chevalier first worked in partnership with his father Vincent, eventually inheriting the shop and becoming well known for the construction of horizontal microscopes. They did not fully solve the problem of chromatic aberration. (Sources: golub collection; camerapedia)