Parabolic mirrors used in pair to produce much higher intensity light beam ready for transmission?

Question

If a parabolic mirror is used to concentrate sunlight  approximately to a focus point why can't an another smaller parabolic mirror be used to reparalelise the beams that are leaving the focal point and depending of the area cross-section finaly get all possible desired densities of the reparalelized beam? Although that high intensity i.e. density reparalelized beams can reach longer distances to transfer energy(?).

hyportnex · Accepted Answer

Of course it can be done although it is rarely used with two parabolic mirrors instead the Gregorian (parabolic + elliptic) or the Cassegrain (parabolic + hyperbolic) systems are used. There are some other variations on the idea, see Schwarzschild or Ritchey-Chretien  systems [1], etc. to increase the field of view. The parabolic+parabolic combination has the disadvantage that its off-axis aberration, coma, is worse than the other two resulting in a very narrow FOV. Also the common focus is located between the two mirrors that is a rather inconvenient place. Compare P+P with P+H or P+E the latter two can bring the focus $out$ behind the primary mirror a much more convenient location.
[1] https://en.wikipedia.org/wiki/Ritchey%E2%80%93Chr%C3%A9tien_telescope

Parabolic mirrors used in pair to produce much higher intensity light beam ready for transmission?

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