1. Technical Field
This invention relates to optical systems, and more particularly to an optical system for producing dual fields of view simultaneously.
2. Discussion
In many applications, it is desirable to have an optical system which can provide multiple views of a scene. Consequently, optical systems such as telescopes have been developed which can provide close up views at high magnification and also, (by changing eye pieces for example), can provide a wider field of view at lower magnification.
Many different configurations exist for altering the magnification and field of view of telescopes, and other optical systems. Such apparatus range from systems where an eye piece is simply changed manually to zoom type optical systems where magnification and field of view are changed in a continuous matter by shifting the position of optical elements. In some cases, however, it would be desirable to have a system for the simultaneous presentation of two different magnifications and fields of view. This is because while one is viewing a close up field of view, one may miss events in the periphery. Conversely, while viewing a wider field of view at lower magnification, one may miss events or details requiring higher magnification. In addition, the mechanism required to shift an optical system from one field of view to another adds bulk and cost to the system.
One solution would be to duplicate the entire optical system thus providing both wide and narrow fields of view simultaneously. Obviously, this greatly increases the cost of the system. In addition, in systems where the optical image is presented to a sensor, such duplications would necessitate duplication of the sensor and further increases in cost and space.
Thus it would be desirable to have an optical system which can provide both wide and narrow fields of view of a scene. Further, it would be desirable to have a system with these features which can provide two fields of view simultaneously. Also, it would be desirable to have such an optical system which can provide the simultaneous dual fields of view at low cost, also which avoids duplication of optical components, and which can be packaged in a relatively compact space. Further, it would be desirable to have an optical system which can provide simultaneous duel fields of view without mechanical action required.