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A prime focus telescope design. The observer/camera is at the focal point (shown as a red X). In a prime focus design no secondary optics are used, the image is accessed at the focal point of the primary mirror. At the focal point is some type of structure for holding a film plate or electronic detector.
The primary reflector is a paraboloid, while the shape of the convex secondary reflector is a hyperboloid.The geometrical condition for radiating a collimated, plane wave beam is that the feed antenna is located at the far focus of the hyperboloid, while the focus of the primary reflector coincides with the near focus of the hyperboloid. [1]
The centrally located sub-reflector serves to focus radio frequency signals in a similar fashion to optical telescopes. An example of a cassegrain radio antenna is the 70-meter dish at JPL's Goldstone antenna complex. For this antenna, the final focus is in front of the primary, at the top of the pedestal protruding from the mirror.
Schmidt corrector plates work because they are aspheric lenses with spherical aberration that is equal to but opposite of the spherical primary mirrors they are placed in front of. They are placed at the center of curvature "C" of the mirrors for a pure Schmidt camera and just behind the prime focus for a Schmidt–Cassegrain. The Schmidt ...
Visible-light camera and spectrograph with the ability to take spectra of up to 100 objects simultaneously, mounts on the Cassegrain focus. Subaru Prime Focus Camera (Suprime-Cam) 80-megapixel wide-field visible-light camera, mounts at the prime focus. Superseded by the Hyper Suprime-Cam in 2012, decommissioned in May 2017.
Most large research reflectors operate at different focal planes, depending on the type and size of the instrument being used. These including the prime focus of the main mirror, the cassegrain focus (light bounced back down behind the primary mirror), and even external to the telescope all together (such as the Nasmyth and coudé focus). [28]
DNEG Group, a visual effects studio and entertainment services technology company known for its work on “Dune” and “Oppenheimer,” has acquired Prime Focus Technologies, an AI-powered media ...
Main types of parabolic antennas. An offset dish antenna or off-axis dish antenna is a type of parabolic antenna.It is so called because the antenna feed is offset to the side of the reflector, in contrast to the common "front-feed" parabolic antenna where the feed antenna is suspended in front of the dish, on its axis.