Patent ID: 6654164
Filing Date: 2003-11-25
Classification: G02B,G03F

Abstract:
An apparatus for imaging light from an extended object on to an image receiver located at a finite distance from the extended object, comprising:a base; a first focusing reflective element, the first focusing reflective element attached to the base, the first focusing reflective element having a first optical axis, the first focusing reflective image receiving a diverging beam of light from the object; a second focusing reflective element, the second focusing reflective element attached to the base, the second focusing reflective element having a second optical axis; a first turning mirror attached to the base, the first turning mirror having a small area compared to areas of the first and second focusing reflective elements, the first turning mirror forming a central obstruction in the diverging beam of light; at least one refractive element attached to the base, the refractive element contributing to the optical correction required to correct the imaging of the extended object on to the image receiver; wherein light emitted from the extended object is transmitted as the diverging beam of light to the first focusing reflective element; and wherein the diverging light beam is reflected from the first reflective element as a converging beam to the first turning mirror, and wherein the light is further reflected from the first turning mirror as a diverging beam to the second reflective element, and wherein the light reflected from the first turning mirror is reflected in turn from the second reflective element and to the image receiver, and wherein the first turning mirror forms a central obstruction to the light reflected from the second reflective element to the image receiver; and wherein the light passes through the at least one refractive element located in at least one position chosen from the group of positions consisting of a position between the extended object and the first focusing reflective element and a position between the second reflective element and the image receiver, and wherein an image of the extended object is formed on the surface of the image receiver.