Saturday, November 17, 2018

ZUFAR 4/350mm and its prototype quartz fluorite catadioptric lens III

Today again about that Quartz Fluorite catadioptric ZUFAR-2CA f4/350mm anastigmat lens which had been developed for the Soviet MARS 2 to 5 missions to planet Mars. I'm rather excited to report that I  found and bought the grandfather of this ZUFAR-2 space lens from planet Mars exploration, a prototype lens with a very different internal name Ob-512, but company data (LOMO) I was able to locate confirmed my suspicion, it is indeed one or even "the" factory prototype of it. 

Top Ob-512 prototype, Bottom: ZUFAR-2CAM lens

The prototype OB-512 also was made of synthetic Quartz and Calcium Fluorite (CaF2) crystals to be able to work in UV and also visible light, designed for 200-700nm without focus shift, so actually is an apochromatic (APO) f4.7/350mm catadioptric lens as per its lens passport. Lens transmission is >57%. Viewing angle is approx. 3 degrees (later 4 degrees). Image diameter 24.6mm. 51mm back focal length. Its weight is 2.2 kilograms, which was later changed in the final ZUFAR-2 CA lens to 1.8 kg using special alloys, as every gram counted then for space missions.

Those ZUFAR lenses have been designed in the 70s under the lead of Institute head and chief designer Prof. Volosov together with N. Khmelnikova, I. Driatskaya, K. Mikhailova at GOI, the russian state lens design institute in St. Petersburg / Leningrad. Details were published by Prof Volosov in 1974.

(Made for my use by my dear friend Marco Cavina)

Optical data of the Ob-512 prototxpe as per Volossov et al.

This lens was made to be used on a very elaborate camera system which could take multispectral images on film, develop that and scan it and send the scanned data back to Earth in selectable resolutions (up to 2000x2000 pix, which took over one hour to transmit).

NASA also wrote about this lens (quote):

Zufar objectives were used on the television cameras carried by the Mars-2, 3, 4, and 5 spacecraft. The compact catadioptric quartz-fluorite anastigmat was developed as a result of research on the possible optical arrangements of lens and mirror-lens systems meeting the rigid criteria for spaceborne operation. The system is characterized by precise correction of all aberrations over a broad spectral range, about 300-700 nm. The spectral transmission is about 60% over this range. The Zufar-2CA version of the objective has a geometric aperture ratio of 1:4 and a focal length of 350 mm. The image format is 24 x 24 mm. The housing is 164 mm long and 130 mm in diameter, and the mass of the objective is 1500 g.

Here one of the published images from Mars taken on Mars-5 mission:

The lens will be given a suitable adaption to fit my digital multispectral cameras and I will certainly take multispectral photos with it as soon as possible and report about here later on.

Data of this lens, as well as its normal (= non catadioptric) quartz fluorite sister lenses with shorter focal length may be found on my macrolenses database site HERE

There is more about this lens HERE.

Stay tuned, more will follow on that fascinating subject...