Re: How Archimedes' Solar Death Ray Could Have Worked

I think the large parabola would focus the light from the Sun to a
point as long as the Sun is reasonably close to aligned to the front of
it, i.e. it doesn't have to be pointed directly at the Sun. The point
the light is focused to, however, would depend on the position of the
Sun and wouldn't always be at the focus of the main mirror. This means
that you only need to move the secondary mirror so that its focus is at
the point where the sun is focused onto. You then get a parallel beam.
Aiming can then be done by moving the secondary mirror, which controls
focus and aiming.

You would probably make the main mirror as a mirror with a hole in the
middle and the secondary mirror would reflect the intensified beam
through the hole. The main mirror would likely be aligned so that it
is aligned to the Sun at midday. The secondary mirror would be mobile,
its position and direction would need to change as the Sun moves.
Using a third plane mirror, as you suggest would allow easier aiming
and a larger range where the beam could be aimed at. Also, this allows
focusing and aiming to be two separate operations. The person
controlling the focus would try to get the spot produced by the
secondary mirror on the aiming mirror as small as possible and falling
on the aiming mirror and then the aimer would direct the beam on the
target.

.

Relevant Pages

  • Re: Where is the evidence pointing to Subh-i Azals succession?
    ... a Manifestation of God. ... The Sun you see in the Mirror is because of the Sun ... << commonly understood by the Bayanis. ...
    (talk.religion.bahai)
  • Re: Where is the evidence pointing to Subh-i Azals succession?
    ... a Manifestation of God. ... The Sun you see in the Mirror is because of the Sun ... understood by the Bayanis. ...
    (talk.religion.bahai)
  • Re: Where is the evidence pointing to Subh-i Azals succession?
    ... a Manifestation of God. ... The Sun you see in the Mirror is because of the Sun ... understood by the Bayanis. ...
    (talk.religion.bahai)
  • Re: parabolic / sperical mirror : How to tell
    ... A parabolic mirror iwll make a more accurately focuse imag eof the sun. ... If the image iw well focused (it will probably have a blur in one direction as you aren't on the axis of the paraboloid) then you probably have a paraboloid. ... A spherical mirror at a short focal length will have a very soft focus with a distant object. ...
    (sci.optics)
  • Re: How Archimedes Solar Death Ray Could Have Worked
    ... point as long as the Sun is reasonably close to aligned to the front of it, i.e. it doesn't have to be pointed directly at the Sun. ... This means that you only need to move the secondary mirror so that its focus is at the point where the sun is focused onto. ... Aiming can then be done by moving the secondary mirror, ... First, sunlight is as close to self-parallel as makes no real difference, hence a paraboloid mirror does indeed focus to a *near approximation of a point*. ...
    (rec.arts.sf.science)
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