Astronomical telescopes

Claim 1

In an astronomical telescope mirror support system having axial support devices supporting the component of mirror weight parallel to the optical axis of the mirror and radial support devices supporting the component of mirror weight normal to the optical axis of the mirror, the improvement comprising means for correcting residual astigmatic distortion produced by changes in orientation of the mirror, said correcting means comprising a plurality of devices for applying forces in a direction parallel to the optical axis of the mirror in the region of the mirror outer edge, which forces increase with an increase in the zenith angle and have a sense and distribution around the mirror edge so as to oppose the said distortion, according to one of the relationships sin z cos2 phi sin z (cos phi ) where (cos phi ) is positive, and sin z (sin phi ) where is positive, where z represents the angle between the mirror axis and the vertical and phi represents the angles between the points at which the forces are applied as projected on a plane tangential to the mirror surface at its center and the vertical, said correcting means supplementing said axial support devices and said radial support devices and acting at the mirror edge only, each device for applying forces having a pivoted lever actuated by a weight at one end and actuating at least one force-transmitting arrangement at the other end, said force transmitting arrangement transmitting said force to a projection on the edge of said mirror.