OFFSET PROJECTION LENS FOR USE WITH REFLECTIVE SPATIAL LIGHT MODULATORS
 Inventors: John A. Tejada, Garland; Douglas W.
Anderson, Richardson; Patrick A.
Trotta, Piano, all of Tex.
 Assignee: Texas Instruments Incorporated,
 Appl. No.: 08/972,646  Filed: Nov. 18, 1997
 Int. CI. G02B 13/22
 U.S. CI 359/663; 359/745; 359/749
 Field of Search 359/663, 649,
359/648, 745, 749, 750, 751, 752, 753
 References Cited
FOREIGN PATENT DOCUMENTS
4-13108 1/1992 Japan 359/663
Primary Examiner—Hung Xuan Dang
US005914818A [ii] Patent Number: 5,914,818  Date of Patent: Jun. 22,1999
Attorney, Agent, or Firm—Charles A. Brill; Frederick J. Telecky, Jr.; Richard L. Donaldson
An offset reverse telephoto projection lens that is telecentric in modulator space and has an air equivalent back focal distance of at least 3.3 inches and preferably at least 4.0 inches. The lens comprising, from the image side, a first objective lens group 408 having a negative power and a second telecentric lens group having a positive power. The second telecentric lens group 410 is telecentric in object space such that the image of the aperture is focused at infinity and light converges on the object plane perpendicular to the axis of the lens. Embodiments of the lens have a back focal distance to effective focal length ratio of at least 0.86:1, preferably at least 1.2:1, more preferably at least 1.3:1, still more preferably at least 4.08:1, and most preferably 5.0:1. The embodiments described have a field of view between 14 degrees and 73 degrees, have throw ratios of 1.2:1 to 7:1, and an overall length ranging from less than 5 inches to 12.5 inches.
30 Claims, 4 Drawing Sheets