Photomicrograph
Microphotography, invented and patented by René Dagron, consists of obtaining very small images (1 mm in diameter) of life-size objects, and includes all the technology necessary for art to make these types of images. Applications for microphotography include espionage, as in the case of William Fischer, to gift items with a viewfinder for travel souvenir shops. Today it is still used in part of the techniques used in the manufacture of microchips, where the image of the circuit is reduced to the micron level.
History
Using a daguerreotype process, John Benjamin Dancer was one of the first to produce photomicrographs, in 1839. Dancer achieved a reduction ratio of 160:1, and perfected his reduction procedures with the wet collodion process, of Frederick Scott Archer, developed in 1850-1851, but dismissed his decades of photomicrograph work as a personal hobby, and did not document his procedures. The idea that microphotography would be just a curious novelty was a view shared by the 1858 Dictionary of Photography, which called the process "a trifling and childish thing".
Microfilm and microfiche
After World War II, important applications of microphotography arose: microfiches, also called microfilms, and different supports for archival and documentation purposes, but with much less reduction (a microfiche has a diameter of 1 cm, compared to 1 mm in diameter for a Dagron photomicrograph). Unfortunately, the development of digital archiving techniques has made this technology increasingly obsolete.
As an example of the use of microphotography for documentation, we can mention article 37 of the Code of Notaries in Guatemala, decree 314 of the Congress of the Republic, which orders the General Archive of Protocols to take microphotographs of the special testimonies that the notaries must send to said institution.