GREEN CARDAMOMS/Gaurangi Maitra
WE ALL have this tremendous hunger to know where and how a story began. It is no different when we come to lenses and microscopes, only there are no single answers or storylines to satisfy our curiosity. So it is not unnatural that in 17th century Europe, lens-making for spectacles was a highly secretive and competitive trade.
This makes the credit given to Zaccharias Janssen and Hans Lippershay for inventing or making the early monocular and compound microscopes highly debatable. It is only known they had both filed a patent for the telescope in 1608 in the Netherlands. We presume, if a tube could house more than one lens for bringing distant objects closer, the same logic could be applied to a microscope. Thus apparently their microscope had two convex lenses aligned in a series within a sliding tube, with no stand and therefore looked like a mini telescope.
By 1624, Galileo had improved upon this compound microscope with the addition of a stand; his microscope looked like a mini telescope on a stand. Not unnaturally his fellow Lincean, Giovanni Faber named it microscope (terminology obviously analogous with the telescope)! By the time Robert Hooke described the microscope he used, its main body was mounted on a wooden stand that freed both hands. The illumination came from a light source brightened by passing through a water flask and focused on the specimen using a lens, and set of screws adjusted the focus of the two lenses.
Thus the basic elements of the 20th century laboratory microscope were already available. What differed was the quality of the lenses available in the1600s.The lenses, however well crafted, were not free from optical aberrations that allowed coloured halos to interfere with the clarity of images in both telescopes and microscopes.
Today the website www.danda.co.uk takes you to what is now Dollond & Aitchson Limited. It was founded in 1750 by Peter Dollond and specialized in manufacture of optical instruments. Peter Dollond’s father John Dollond held the rather controversial patent for the achromatic double lens by virtue of the fact he was able to take forward and ‘exploit’ the technology involved! John Dollond backed up the claim in 1758 by publishing an “Account of some experiments concerning the different refrangibility of light” in the Philosophical Transcations of the Royal Society. He was awarded the Copley Medal and made a fellow three years later for having constructed achromatic double lenses by the combining crown and flint glasses, thereby reducing chromatic aberration.
The word exploit has an interesting connotation here. The idea of the achromatic double lens apparently originated with an attorney named Chester Moore in 1733. Since Moore was not an optician, he contacted two individuals to make the two different lenses to ensure secrecy. Unfortunately for him, they both outsourced the work to George Bass. The latter realizing the potential of the material in hand, apparently kept it secret till he met John Dollond who was also experimenting with achromatic lenses. Dollond patented, published and produced achromatic lenses and fine optical ware, leaving Moore and Bass out in the cold. They are the oldest retail opticians on High Street in London 264 years down the line, employing about 2,500 persons with Andy Ferguson as CEO and Pradip Patel as MD.
From the mid-1700s onwards, these lenses were available for telescopes but microscopes would have to wait another 50 years for the technology to evolve to craft fine small achromatic lenses suitable for microscopes.
Enter Giovanni Battista Amici, Italian instrument maker, astronomer, microscopist and botanist in 1824. It heralds the birth of the achromatic microscope. In England nearly concurrently worked Joseph Jackson Lister, the father of Joseph Lister of antiseptic fame. He corresponded with Amici mentioning his surprise at the near simultaneous production of short focus achromatic lenses in England and Italy. Lister Senior knew instrument maker William Tulley had ‘executed his first good triple 0.4 inch’ in 1824; he submitted a paper to the Royal Society “On Some Properties in Achromatic Object-Glasses Applicable to the Improvement of the Microscope” in 1831. It was the first account of fully achromatically and spherical methods for compound microscopes and stated his law of aplanatic foci. This was a culmination of his work in the mid-1820s and by the last part of that decade he had roped in Tulley to make microscopes.
Some of the big names in microscopy of the 20th century had already set up shop in the 1800s – Powell, Lealand and Smith in 1841, Carl Zeiss in 1847 and Bausch and Lomb in 1853. Thus the 1800s would see widespread use and improvement in technology and manufacture of microscopes. That this revolutionised the nascent science of biology as a whole and played a vital role in physical sciences is a complete understatement. ([email protected])
[Main resources: Wikipedia; www.danda.co.uk]