and and ([[xi].sub.1], [[eta].sub.1], [[zeta].sub.1]) and ([[xi].sub.2], [[eta].sub.2], [[zeta].sub.2]) are the cartesian coordinates of the points on the paraboloidal and hyperboloidal reflectors, respectively.
while [R.sub.1] and [R.sub.2] are the distances from the point ([[xi].sub.2], [[eta].sub.2], [[zeta].sub.2]) on the hyperboloidal reflector to the caustic points z = c and z = -c, respectively.
We will take two, RR and LL, waves that will incident on hyperboloidal subreflector and converge as well after reflection.
The cylindrical fragment changes into
hyperboloidal fragment with variable section (Plahteanu & Belous, 2000).
In order to calculate the zone plate efficiency, the chord length squared (proportional to zone plate intensity at the focus) is divided by the corresponding arc length squared (proportional to hyperboloidal lens focal contribution).
Since the zone plate is thinner than a lens, it has lower dielectric loss, lower weight and smaller volume than a lens, and because of planar construction, is easier to fabricate, especially compared to an ideal lens with hyperboloidal curvature.
Did I really have to shoot for a
hyperboloidal secondary when I had gotten such a fine image with a spherical convex mirror?
A well-annealed mirror becomes overcorrected (slightly
hyperboloidal) while cooling down.