Abstract: An optical system affords wide-angle imaging with a width in azimuth and a height in elevation respectively greater than and less than those of the field of view of an imaging device to which it is fitted. A median optical axis images a central format view on the optical axis of the imaging device, and two lateral optical paths image two lateral format views on a bearing axis at a bearing angle to the optical axis equal to the width in azimuth of the field of view of the imaging device. The three paths juxtaposed in the wide-angle field of view are superposed into a resultant format image.

Abstract: A mirror device for providing an image of a remote object, suitable for use in a multi-spectral collimator, comprises a primary concave mirror whose surface is an off-axis portion of a paraboloid having a rotational symetry about an axis, and a secondary concave mirror whose surface is an off-axis portion of a hyperboloid, one focus of which coincides with the focus of the paraboloid. The mirrors have sizes of the same order of magnitude. The primary mirror is so located that a light beam received by it and having a mean ray parallel to the axis of the paraboloid is unobscured by the secondary mirror. The radii of curvatures of the two mirrors at locations along their respective axes do not differ by more than 10%.