Top Secret: Microdot (10 photos)

One of the most secret technologies of intelligence communications of the 20th century was considered to be a microdot.

In important cases, when security issues were given exceptional attention, the intelligence services of countries used special technical means and methods of obtaining “microscopic” photographic images, which were so small that, even knowing about their presence, they were practically impossible to detect without knowing the exact location.





In 1839, after the invention of the photographic process, the English designer of instruments for scientific experiments John Dancer achieved a reduction in the photographic image by 160 times. The Frenchman René Dagron went further and adapted this photo process to create a large number of microletters and deliver them by pigeon post to Paris, which was besieged by German troops in 1870. At that time, this method of secret communication was already considered a French military secret.



Emmanuel Goldberg

Emmanuel Goldberg is considered the father of modern microphotography methods. He was born in 1881 in Moscow, into the family of a military surgeon, and after studying at Moscow University, he began working in Dresden, at the famous Carl Zeiss company. In 1925, at the International Photographic Congress in Paris, Goldberg demonstrated an original setup for obtaining micro images and showed a wide audience the process of making a special high-resolution photographic layer, without which it is impossible to create a micro letter. These works by Goldberg later became the basis for the emergence of many well-known methods for making spy micro letters and constructing special equipment for micro photography. Goldberg did not set himself the task of creating a portable setup for obtaining spy micro images. However, the scientist showed everyone a classic optical scheme, which the intelligence services of the leading countries of the world took as a basis for developing their own compact and accessible devices for operational use.

The micro letter made and shown by Goldberg in Paris looked like an ordinary period at the end of a sentence. This is where the name "micro dot" came from for all known methods of secret communication, in which a sheet of A4 text could be placed entirely on a piece of film measuring 1 x 1 mm or even smaller.

A tiny transparent piece of film can be hidden anywhere - in books, postcards, letters, envelopes, small parcels and any other household items.





The main significance of E. Goldberg's message was that he not only described in detail the practical method for obtaining micro images that he had developed, but also demonstrated a real micro dot - "mikrat", as he called it, with a significantly greater reduction of the original than had been possible before. In addition, each participant of the photo congress was given a memorial copy of the micro dot made by E. Goldberg. It was a glass plate with a portrait of the inventor of photography, Nicéphore Niépce, framed in an elegant leather wallet. The size of the portrait itself did not exceed 0.03 mm! The portrait was framed by a circle divided into 360 sectors with spaces of 1 micron. Each sector contained a number of 2 microns.



In 1925-1937, on the initiative of “Geheimsache” in Germany, work began on improving microdots - the highest achievement in the field of microfilming.

At the end of the 1930s, specialists from Agfa, one of the world's leading manufacturers of photographic materials, developed high-resolution HR photographic plates for astrophysics and spectrography, also known as Agfa-Mikrat-Platten.

Zeiss-Ikon, where the director at one time was the creator of "real" microdots E. Goldberg, carried out work to simplify the process of obtaining micro images. It released a portable reproduction camera for making ultra-microfilms from A4 originals. The image size on a 4 mm wide film was only 2 sq. mm.



On November 18, 1937, Hans Ammann-Brass, a Swiss by birth, a graduate of the Berlin Higher Technical School, was given the task by the Abwehr to improve the technology for producing microdots. The technical note set the task of creating a device for producing microdots with a reduction ratio of up to 1:750.

In the period before and during the Second World War, microphotography was most actively used by the German secret services. And it is not only that it was in Germany that they were brought to such a perfect state that practical application did not cause difficulties for the executors. German intelligence widely used microfilms to transmit information.

After the war, it became clear that many German embassies in Latin America had well-equipped photo labs - a kind of microdot factory. No less important was the use of microdots for communication between the Center and the agent. They were sent instructions, tasks and even personal letters. In the case of a well-established mail channel, microdots became an extremely reliable and cheap means of communication.



World War II was over. The former allies were increasingly looking like enemies. After the end of World War II, the former allies began a real hunt for German technology. The same thing happened with the microdot. Only special HR (high resolution) film is suitable for making microdots, as well as Lipman emulsion, its resolution can reach 6000 lines/mm.

Speaking of microdot, we must not forget that in addition to a fine-grained emulsion, one of the indispensable conditions for successful work is a high-quality lens. Back in 1925, the father of microdot E. Goldberg noted the need to use a microscope objective with a focal length of 20 mm and a flat image field. Such objectives are produced by leading manufacturers of optical instruments Leitz, Zeiss, Nikon. They are very expensive, and their presence is typical only for forensic or crystallographic laboratories. A serious problem in the manufacture of microdots has always been equipment vibration during long exposures.





Another very specific problem arises from the main property and even advantage of the microdot - its inconspicuousness and extremely small size. A microscopic piece of transparent cellophane is so easy to drop and lose without a trace! Experience shows that if you do not know exactly where the microdot is hidden, or drop it on the floor, especially on a carpeted floor, it is almost impossible to find it. Perhaps that is why the microdot was used in espionage practice in exceptional cases. In any case, obtaining micro images with a reduction ratio of 1:400 is the lot of professionals from the relevant laboratories of leading intelligence agencies.