Super-Schmidt

Super-Schmidt

 

a catadioptric telescope system in which the spherical aberration of the concave spherical mirror is corrected by a complex combination of a Schmidt corrector plate and one or two meniscus lenses. The best-known system of this type is the super-Schmidt camera of J. Baker, in which two meniscus lenses that are concentric with the mirror almost completely compensate for the mirror’s spherical aberration. The meniscus lenses do not disrupt the symmetry of oblique beams. The remaining spherical abberation is removed by an aspheric achromatized Schmidt corector plate placed at the common center of curvature of the mirror and the meniscus lenses. The field of view of the Baker super-Schmidt camera reaches 55°, with a relative aperture of 1:0.67. The camera is used to take pictures of meteors.

Another super-Schmidt system is the Astrodar objective, developed by Soviet optical designers D. D. Maksutov and M. A. Sosnina and used in the large Soviet VAU satellite camera.

The entrance pupil of a super-Schmidt camera may be up to 0.5 m in diameter (for a mirror 1 m in diameter). Super-Schmidt cameras are also used for tracking artificial earth satellites.

REFERENCES

Maksutov, D. D. Astronomicheskaia optika. Moscow-Leningrad, 1946.
Riekher, R. Fernrohre und ihre Meister. Berlin, 1957.

N. N. MIKHEL’SON

References in periodicals archive ?
Baker (famed for the Baker-Nunn satellite tracker and Super-Schmidt meteor camera) wrote, "The Schupmann does happen to be the most nearly perfect telescope mathematically."
Baker was well known for his super-Schmidt meteor cameras used by Harvard Observatory.
Many ultrafast and ultra-wide-angle cameras, such as the Baker Super-Schmidt, employ meniscus ideas.
where k is a proportionality factor that can be adjusted for lens quality and light loss, and the exponent n is "probably near unity but may be as high as 2." Also, x is the ratio of the time a camera is closed to the time it is open -- a matter to be considered if a chopping wheel interrupts the meteors to provide a measure of angular velocity, or if (as in the super-Schmidt) the dead time while changing film is significant.
For fun I also plugged in data for the Ross Xpress and K-19 lenses Whipple used a half century ago, di Cicco's customized fisheye, and the Baker super-Schmidt (covering 2,376 square degrees).