Concave mirror optical system for scanner

Abstract

A concave mirror optical system for a scanner and a method for compensating image distortion. In this invention, the more expensive lens assembly in a conventional optical system is replaced by a concave mirror made from simple low-cost material so that production cost and chromatic dispersion are reduced. Moreover, different magnifications can be obtained due to a difference in focusing power of the concave mirror along XY axis direction.

1. A concave mirror  An optical system for a scanner , comprising:
 a first concave mirror having a first  concave surface for receiving  configured to reflect a beam of incoming light received directly from a document;  
 a second concave mirror having a first  concave surface for receiving  configured to reflect the reflected  light reflected from the first concave mirror;  
 a third concave mirror having a first  concave surface for receiving  configured to receive the reflected light from the second concave mirror and focusing  to focus the reflected light to a focal point, wherein the first concave mirror, the second concave mirror, and the third concave mirror each include short edges and long edges, wherein the short edges of the first concave mirror and the second concave mirror curve to form corresponding concave surfaces of the first concave mirror and the second concave mirror, and wherein the long edges of the third concave mirror curve to form the concave surface of the third concave mirror; and  
 an optical sensor whose receiving end is  positioned at the focal point for receiving  to receive the reflected light reflected  from the third concave mirror.  
 
     
     
       2. The optical system of  claim 1 , wherein the first concave mirror and the second concave mirror are substantially identical. 
     
     
       3. The optical system of  claim 1 , wherein the first concave mirror and the second concave mirror includes a first long edge, a second long edge,  each include a first short edge,  and a second short edge, a first surface and a second surface, and  wherein the first short edge and the second short edge are curves forming  curve to form a concave first  surface and a convex second  surface. 
     
     
       4. The optical system of  claim 1 , wherein the second  third concave mirror includes a first long edge,  and a second long edge, a first short edge, a second short edge, a first surface and a second surface, and  wherein the first short  long edge and the second short  long edge are curves forming  curve to form the a concave first  surface and a convex second  surface. 
     
     
       5. The optical system of  claim 1 , wherein the optical sensor includes a charge couple device (CCD). 
     
     
       6. The optical system of  claim 1 , wherein the optical sensor includes a contact image sensor (CIS). 
     
     
       7. An apparatus, comprising:
   a mirror assembly configured to reflect light received from a document, wherein the mirror assembly includes a plurality of mirrors having concave surfaces, wherein the mirrors directly reflect the received light between the concave surfaces, wherein each of the mirrors includes short edges and long edges, and wherein the short edges curve to form the concave surface for at least one of the mirrors and the long edges curve to form the concave surface for at least another one of the mirrors; and        an optical sensor positioned at a focal point and configured to receive light reflected from the mirror assembly.     
     
     
       8. The apparatus of  claim 7 , wherein the mirror assembly comprises a first concave mirror having a concave surface to reflect the received light to a concave surface of a second concave mirror, wherein the first concave mirror is configured to receive the light directly from the document. 
     
     
       9. The apparatus of  claim 8 , wherein the mirror assembly further comprises a third concave mirror having a concave surface to focus light reflected from the concave surface of the second concave mirror. 
     
     
       10. The apparatus of  claim 9 , wherein the third concave mirror comprises a first long edge and a second long edge, and wherein the first long edge and the second long edge curve to form the concave surface of the third concave mirror. 
     
     
       11. The apparatus of  claim 8 , wherein the first concave mirror and the second concave mirror each include a first short edge and a second short edge, and wherein the first short edge and the second short edge curve to form the corresponding concave surfaces. 
     
     
       12. The apparatus of  claim 8 , wherein the first concave mirror and the second concave mirror are substantially the same. 
     
     
       13. The apparatus of  claim 7 , wherein the optical sensor comprises a charge couple device ( CCD ). 
     
     
       14. The apparatus of  claim 7 , wherein the optical sensor comprises a contact image sensor ( CIS ). 
     
     
       15. A system, comprising:
   a first mirror comprising a concave surface configured to, at least in part, reflect incident light;        a second mirror comprising a concave surface configured to, at least in part, reflect incident light received from the first mirror; and        a third mirror comprising a concave surface configured to, at least in part, reflect incident light received from the second mirror and, at least in part, focus the received reflected light on an optical sensor, wherein the first mirror, the second mirror, and the third mirror each include short edges and long edges, wherein the short edges of the first mirror and the second mirror curve to form corresponding concave surfaces, and wherein the long edges of the third mirror curve to form the concave surface of the third mirror.     
     
     
       16. The system of  claim 15 , wherein the first mirror and the second mirror are substantially the same. 
     
     
       17. The system of  claim 15 , wherein the first mirror and the second mirror each include a first short edge and a second short edge, and wherein the first short edge and the second short edge curve to form the respective concave surfaces. 
     
     
       18. The system of  claim 15 , wherein the third mirror comprises a first long edge and a second long edge, and wherein the first long edge and the second long edge curve to form the concave surface of the third mirror. 
     
     
       19. A method, comprising:
   reflecting light received directly from a document with a first concave surface, wherein the first concave surface includes one or more short edges and one or more long edges, and wherein the one or more short edges curve to form the first concave surface;        reflecting light received from and reflected by the first concave surface with a second concave surface, wherein the second concave surface includes one or more short edges and one or more long edges, and wherein the one or more short edges curve to form the second concave surface;        focusing the light received from and reflected by the second concave surface with a third concave surface, wherein the third concave surface includes one or more short edges and one or more long edges, and wherein the one or more long edges curve to form the third concave surface; and        sensing the light focused by the third concave surface.     
     
     
       20. The method of  claim 19 , wherein said sensing is performed at a focus of the light from the third concave surface. 
     
     
       21. The method of  claim 19 , wherein said sensing is performed by a charge couple device ( CCD ). 
     
     
       22. The method of  claim 19 , wherein said sensing is performed by a contact image sensor ( CIS ). 
     
     
       23. A system, comprising:
   means for reflecting light received from a document with a first concave surface, wherein the first concave surface includes one or more short edges and one or more long edges, and wherein the one or more short edges curve to form the first concave surface;        means for reflecting light received from and reflected by the first concave surface with a second concave surface, wherein the second concave surface includes one or more short edges and one or more long edges, and wherein the one or more short edges curve to form the second concave surface;        means for focusing the light received from and reflected by the second concave surface with a third concave surface, wherein the third concave surface includes one or more short edges and one or more long edges, and wherein the one or more long edges curve to form the third concave surface; and        means for sensing the light focused from the third concave surface.     
     
     
       24. The system of  claim 23 , wherein the means for reflecting light with a first concave surface and the means for reflecting the light with a second concave surface are substantially identical.