Abstract: An optical assembly which provides a cylindrical mirror of adjustable focal length, adjustable angle of elevation, adjustable horizontal orientation and adjustable angle of focus. The mirror is formed of a thin member of a spring material and it is mounted on a four-point support system comprising sets of inner and outer loading points. Means are provided to move one set of loading points relative to the other set to control and adjust the radius of curvature and hence the focal length of the mirror. Means are also provided to tilt the mirror, to orient it in a horizontal plane and to orient the line beam it forms to control the angle of focus.