By Eduard Trigubov and Yuri Petrunin
In the annals of telescope making there is a single name that
has become synonymous with ingenuity, innovation, elegance of
design, and optical quality: Maksutov. While not the first to
consider melding the best attributes of refracting and reflecting
telescopes into a single instrument, Dmitri Maksutov did conceive
an optical system that was to spawn a class of very compact,
high-definition instruments that would be relatively easy to
The year 2001 marked the 60th anniversary of the invention of the meniscus catadioptric telescope by this remarkable Russian optician. Despite the current resurgence in popularity of his telescope designs, the story of Maksutov's tumultuous life remains largely unknown in the English-speaking world and his family's extensive connections to America will come as a surprise to most readers.
Dmitri Dmitriyevich Maksutov was born on April 11, 1896, in the Russian city of Nikolayev, and three years later the family moved 70 miles to the port city of Odessa. His father, a naval officer serving with the Black Sea fleet, came from a family with a long and distinguished naval tradition. His great-grandfather, Peter Ivanovich Maksutov, was given the title of prince thereby raising the family to hereditary nobility as a reward for bravery in combat. His grandfather, Dmitri Petrovich Maksutov, was the imperial governor of Alaska when the United States purchased this vast territory for two cents an acre in 1867.
After graduating from cadet school in 1913, Maksutov enrolled in the Military Engineering College, located in the czarist capital of St. Petersburg.
Maksutov served with distiction in the First World War. This photograph of Porichik (Lieutenent) Maksutov was taken in St.Petersburg in 1916, on leave after serving at the front in the Caucasus Mountains.
|When the First World War broke out in August of the
following year, classes were canceled and the students were sent to
the frontlines to fight. Maksutov served with distinction in the
Caucasus as a radio operator, winning promotion to the rank of
In 1916 he volunteered for flight school, where he cheated death during a training flight as his flimsy aircraft disintegrated around him. He miraculously survived a fall from an altitude of more than 200 feet, but the serious injuries he sustained required prolonged hospitalization. Maksutov was discharged from the hospital soon after the 1917 revolution and almost immediately attempted to emigrate to the United States via China. Yet he made it only as far as Harbin (Manchuria) before his infirmities and a lack of funds forced him to turn back.
The ravages of World War I and the Russian Revolution in 1917 led to difficult times for the Maksutov family. Political tensions had a far greater impact on the other male members of his immediate family. His mother remained in Odessa, but Maksutov's father and younger brother, Konstantin, who had fought the Communists during the Revolution, fled to France. Later they would emigrate to the United States and eventually settle in Long Island, New York. Maksutov's father subsequently served in the merchant marine and died in 1958. Konstantin took up chemical engineering and lived until 1987. Since Dmitri's grandmother was buried in the Alaskan town of Sitka, three generations of Maksutovs are buried on American soil.
In the early 1900s Dmitri's interest in astronomy was awakened by a gift from his grandfather a small, 150 year-old, mahogany-and-brass Dollond refractor. He longed for a more powerful telescope, but commercial instruments from Germany were prohibitively expensive. So, at age 15, the budding astronomer decided to build one from scratch. He ground and polished a 7-inch mirror, fabricated a Newtonian telescope around it, and began to make regular observations. He was soon elected a member of the Russian Astronomical Association, and the first of his many articles about mirror making appeared in the organization's journal. In 1919 Maksutov traveled to the central Siberian city of Tomsk, where he enrolled in the Tomsk Technical Institute.
The ravages of Russia's civil war had resulted in a
severe shortage of teachers, so despite his student status Maksutov
taught classes in physics while continuing to study optics. One of
his professors noticed his extraordinary talent and spoke highly of
him to Dmitri Rozhdestvensky, the founding director of the State
Optical Institute in St. Petersburg an organization better
known by its acronym, GOI. Accepting an offer to join the staff
there, he worked under the supervision of wellknown optician
Aleksander Chikin, the author of a popular book on mirror making
who is remembered today as one of the "patron saints" of Russian
amateur telescope makers.
He soon left St. Petersburg to join her, supporting his family by making optics for Odessa Observatory in a home workshop as well as teaching classes in mathematics and physics. In 1927 he took a job at the Odessa State Physical Institute, where he quickly organized a workshop to manufacture telescopes for schools. Within a year he turned out a hundred wellmade 5½-inch Newtonian telescopes, all with firstclass optics, ground and polished by hand.
In February 1930 Odessa was subjected to a purge and, like hundreds of other suspected enemies of the Soviet regime, Maksutov was arrested. He later described the ordeal as the worst experience of his life there were no trials, and every other randomly chosen suspect was shot. But fate smiled on Maksutov once more, and he was released in the middle of March. Three months later he accepted an invitation to return to GOI in St. Petersburg, where he once again started making astronomical optics in a workshop that would become the Soviet Union's most important training ground for opticians.
This proved a fertile time for optical innovation. Unaware of the
research of George Ritchey, Karl Schwarzschild and Andre Couder,
Maksutov independently produced his own aplanatic reflecting
telescope designs. This constituted one of his greatest theoretical
works and was published in the GOI bulletin in 1932. He also
developed a new method of testing the figure of mirror surfaces,
similar to the famous Ronchi test, that used a grating with curved
rather than straight lines. This approach was identical to the null
test independently invented many years later by Eric Mobsby in
England (S&T: November 1974, page 325), among others. He also
strove to improve the traditional Foucault knife-edge test.
Although Maksutov published dozens of valuable articles describing
these innovative techniques, his work remained all but unknown to
foreign opticians due to the effective isolation of the U.S.S.R.
prior to World War II.
Maksutov's first major undertaking was the 32-inch objective lens for the large refractor at Pulkovo Observatory near St. Petersburg. This instrument had been ordered from the famous English firm of Grubb Parsons in 1913. All the components except the objective lens had been delivered by 1926, and after several unsuccessful attempts to procure a satisfactory objective lens in England and Germany, the decision was made to produce one at GOI.
But the project suffered many setbacks. Repeated failures to cast a
blank for the crown-glass element were exacerbated by Maksutov's
strained relations with his co-workers arising from their
perception of him as a "class enemy" owing to his titled
background. These difficulties ultimately resulted in his arrest in
1937. Officials accused him of sabotage, long delays in selecting
the crown element of the 32-inch objective, and spying for Japan.
Although these accusations were utterly baseless, Maksutov spent
nine months in prison and did not complete the objective until
1946. By then the era of large refractors had long since passed,
and this superb lens simply became a relic displayed in Pulkovo
During the 1930s Maksutov's opticians found time to produce a wide variety of extremely challenging optical systems, including fast apochromatic objectives, aspheric projection lenses, two 14-inch f/2 Schmidt cameras, a 16-inch aplanatic reflector for Byurakan Observatory in Armenia, and a 20-inch horizontal solar telescope for Pulkovo. Maksutov's work was not limited to practical optics. He also applied for more than 10 patents, and published several articles and books including: "Aberration-free reflective systems and methods of their control" (1932); "Shadow methods of testing optical systems" (1934); "Optical flats, testing and manufacturing"(1937).
Maksutov was hard at work on his astronomical instruments when
the Germans invaded the Soviet Union in 1941. As Hitler's armies
prepared to encircle and lay siege to Leningrad (formerly St.
Petersburg), many scientific and industrial organizations,
including GOI, were evacuated far to the east out of harm's way. It
was during a long journey by train to remote Soviet Central Asia
that Maksutov once again began to contemplate the design of a
telescope suitable for schools. The result was the invention of his
now famous meniscus system. Five years later in his book
"Astronomical optics", Maksutov recounted how his thoughts unfolded
on the trip:
Is everything satisfactory with the construction of the small reflector? Will it last for long? No, such telescopes contain aluminized mirrors, which need realuminizing after a while. How can this be avoided? One solution would be to place a plane-parallel window at the front of the telescope. This would increase the cost of the telescope, but we need to do it if we wish to produce a rugged telescope for schools. A closed tube would also be desirable because thermal convection currents inside the tube would be reduced, improving image quality.Thoughts continue... The same window could hold the diagonal mirror, so the telescope would be free of spider vanes, eliminating diffraction spikes in the images of stars. Thoughts continue... What if, in other optical configurations like the Gregorian or the Cassegrain, the secondary mirror were attached to the optical window? What if this window were made not in a plane-parallel form, but as a meniscus lens with an internal curvature equal to the surface radius of the secondary mirror?
In this case, the secondary mirror would become an aluminized
spot in the central part of the meniscus. Such a system seems very
appealing, because the central obstruction would be minimized and
there would be no chance of secondary mirror becoming
It was clear from the beginning that such a meniscus lens could be made achromatic (bringing all colors to the same focus), but a quick calculation showed that it would produce noticeable spherical aberration. At this moment, Maksutov nearly missed the discovery by turning his thoughts to calculating a meniscus free of spherical aberration. Then it dawned on him that the meniscus lens could introduce positive spherical aberration to compensate for the negative spherical aberration of a spherical primary mirror, or system of mirrors, without introducing chromatic aberrations.
This spark of genius didn't come totally out of the blue. Maksutov's notebooks reveal that in 1936, when he was contemplating Mangin mirrors (lenses with one silvered surface, primarily used in spotlights and lighthouse beacons), he had penciled in the margin a little sketch showing the reflective and refractive elements of a Mangin mirror separated to form a meniscus lens and a mirror. And in 1929 he published a paper describing a family of achromatic meniscus lenses. So it's fair to say that his meniscus concept from first thoughts to final realization gestated for at least a dozen years.
Maksutov completed his first meniscus telescope on October 26, 1941, just three weeks after arriving at Yoshkar Ola in present-day Kazakhstan. He applied for the meniscus optical systems patent on November 8, 1941. The performance of this little instrument, a 100-mm f/8.5 Gregorian, was outstanding. The Maksutov-Gregorian design calls for the concave side of the meniscus lens to face the primary mirror. Turning the meniscus around permits its use in a Maksutov-Cassegrain telescope precisely the configuration now employed in a multitude of commercial models.
As the Soviet Union fought for its survival in World War II, almost all production served the needs of the military. Yet the war years were among Maksutov's most productive and innovative. In a single year he performed the laborious and time-consuming calculations for more than 200 meniscus-based optical systems, ranging from small glasses to a 40-inch planetary telescope ? a remarkable feat during the era of slide rules and logarithm tables. More than 500 calculations were done up until the end of 1944 and all classic mirror systems were modified to meniscus systems. Today such instruments are widely known under names like Simak and Rumak, but they have their genesis in Maksutov's wartime notebooks.
In November 1943 Maksutov began working at the prestigious Academy of Sciences in Moscow. By this time the fortunes of battle favored the Russians, but the retreating Germans were systematically plundering and burning the Soviet Union's finest observatories. Maksutov's new systems were therefore given much attention as potential replacements for the destroyed instruments.
In 1944 Maksutov's article "New Catadioptric Meniscus Systems" was published both in the GOI's bulletin and as a translation in the Journal of the Optical Society of America (volume 34, pages 270-284). These articles resulted in such widespread acclaim that Maksutov received the title "professor" without having to write and defend a dissertation. In 1946 he was granted a patent and awarded a government prize "for the creation of new types of optical systems." Yet despite this long-overdue international recognition, Maksutov's superiors never permitted him to travel abroad. How capricious that he received the Order of Lenin twice (in 1941 and 1946), yet he'd been imprisoned in 1937.
After the war, Maksutov returned to GOI, where the first three
astronomical meniscus telescopes were completed. One early model,
designated MTM-1, was an 8-inch Maksutov-Cassegrain with a Nasmyth
focus carried on an equatorial fork mounting. More than a half
century later, this instrument still looks strikingly modern. Under
Maksutov's supervision, a local factory began to manufacture a
70-mm f/10 Maksutov-Cassegrain telescope equipped with two
eyepieces in a revolving turret. Soon examples of this instrument
could be found in every secondary school and university in the
Despite his workload, Maksutov somehow managed to find the time not only to lecture at Pulkovo but also to write two textbooks, Astronomical Optics (1946) and The Manufacture and Testing of Astronomical Optics (1948). These works contain a vast amount of practical information and served as a basic guide for succeeding generations of Russian opticians. Fortunately, there are plans afoot to translate them into English.
During the late 1940s and 1950s, Maksutov oversaw the fabrication of numerous large-aperture optical systems for professional use. Today his instruments can be found at observatories throughout the former Soviet Union. These include: two 20-inch f/13.5 planetary meniscus telescopes with non-moving (Coude-type) focal positions for Pulkovo and Crimea; a 20-inch f/2.4 Meniscus camera ASI2 in Alma-Ata (Kazakhstan); a 20-inch f/4.0 Meniscus camera AZT-5 in Crimea (Ukraine); a 700mm (27.6-inch) universal meniscus telescope with dual f/3 and f/15 foci in Abastuman, (Georgia).
In 1951 he even submitted plans for a 4-meter telescope, but political forces dictated something larger than the 200-inch (5-meter) telescope atop Palomar Mountain, and eventually his team led the design effort for the 236-inch (6-meter) "Large Altazi-muth Reflector" (known by its Russian acronym, BTA) now operating high in the Caucasus Mountains.
Maksutov's best and final work is generally regarded to be the 70-centimeter- (27.6-inch-) aperture double-meniscus astrograph known as the AZT-16. This instrument was needed for fundamental astrometry, a demanding application that required a fast focal ratio and a large field free of lateral color and distortion. Maksutov employed a pair of meniscus correctors to satisfy these exacting parameters. Deteriorating health left him little time to finish this project.
He did finish the optics, though the entire instrument was not
completed until late 1964, a few months after his death on August
12th. The AZT-16 entered service four years later on Cerro Roble in
the Chilean Andes.
Maksutov's interests were not devoted solely to the development of astronomical optics. He designed a gastroscope (an instrument for photographing the interior of the esophagus and stomach), for which he was granted the first of his many patents. He also invented a "microscope needle" for examining living cells inside the human body. This was a particularly challenging optical device: the "needle" is 4 mm wide and employs a six-lens objective, with the largest lens being 2.2 mm in diameter.
A rare combination of creative optical designer and master optician (he always took greater pride in the latter), Maksutov deserves to be called the father of the Russian school of astronomical optics. His books and instruments are enduring monuments that pay eloquent testimony to the range and quality of his work. His own words are perhaps the most fitting epitaph: "I always valued work more than life itself.