Controlled distortion

An optical system producing an image with non-constant magnification across the field of view, or optical distortion, is traditionally considered as undesirable. It is unpleasant and harder to interpret for a human observer to look at a curved image when the original object is straight. However, this should not be a limiting factor as it is possible to unwrap the image at the software level as long as object to image mapping is well known. This is often used to straighten the image from a wide-angle lens because of their natural tendency to have important distortion. Since it can be advantageous in information optics to image a certain part of the field of view with higher magnification while keeping a full surrounding view, the use of controlled distortion by optical designers to voluntary create zones of different magnification is now common. In this paper, we first explain the concept of controlled distortion from an optical design point of view. Advantages and applications of static controlled distortion, by example in wide-angle lenses already on the market, are then presented. Finally, extension of this concept to dynamically controlled distortion by using active surfaces is presented. Experimental results from a dynamic controlled distortion imager using a deformable mirror are shown.