Re-imaging optical system including refractive and diffractive optical elements

• US 5,287,218 A
• Filed: 04/07/1992
• Issued: 02/15/1994
• Est. Priority Date: 04/07/1992
• Status: Expired due to Fees

• Current Assignee: Hughes Aircraft Company (Rtx Corporation)
• Original Assignee: Hughes Aircraft Company (Rtx Corporation)
• Inventors: Chen, Chungte W.
• Primary Examiner(s): Arnold, Bruce Y.
• Assistant Examiner(s): PARSONS, DAVID
• Application Number:
  US07/864,858
• Time in Patent Office: 679 Days
• Field of Search: 359/362, 359/364, 359/365, 359/399, 359/423, 359/434, 359/558, 359/565, 359/566, 359/569, 359/724, 359/726, 359/727, 359/730, 359/857, 359/858, 359/861, 359/864
• US Class Current: 359/365
• CPC Class Codes: G02B 17/0812 off-axis or unobscured systems in which all of the mirrors share a common axis of rotational symmetry
• CPC Class Codes: G02B 17/0832 off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements
• CPC Class Codes: G02B 17/0852 having a field corrector only
• CPC Class Codes: G02B 27/0037 with diffracting elements G02B27/0056 takes precedence; holographic optical elements G02B5/32; zone systems G02B5/1876
• CPC Class Codes: G02B 27/4211 correcting chromatic aberrations G02B27/0056, G02B27/4222, G02B27/4227 take precedence
• CPC Class Codes: G02B 27/4216 correcting geometrical aberrations

Abstract

A re-imaging optical system (10) has a ref lective objective (12) providing an intermediate image of the object being viewed and a relay (14) including refractive (32, 62) and diffractive (34, 72) optical elements. The system is capable of re-imaging the intermediate image onto an image plane (16) with the characteristic advantages of reflective and refractive systems while eliminating their deficiencies.

Claims

1. A re-imaging optical system comprising:

an objective including a primary and secondary mirror, said primary and secondary mirrors having conic or higher order aspheric surfaces, said primary mirror receiving and projecting a radiation beam of a viewed object, said secondary mirror positioned to receive and reflect said radiation beam from said primary mirror, said primary mirror forming an intermediate image of said viewed object;

a relay means including a refractive optical element and a diffractive optical element positioned to receive said radiation beam from said secondary mirror to re-image said intermediate image onto an image plane.

2. The system according to claim 1 wherein a fold mirror is positioned between said primary and secondary mirrors for relaying said radiation beam to said secondary mirror.

3. The system according to claim 1 wherein said primary mirror and said secondary mirror are each positive power mirrors.

4. The ssytem according to claim 1 wherein said refractive and diffractive optical elements have positive optical power.

5. The system according to claim 1 wherein said refractive and diffractive optical elements are a single hybrid optical element.

6. The system according to claim 1 wherein said refractive optical element includes a pluraliyt of lenses.

7. The system according to claim 6 wherein said plurality of lenses includes positive and negative power lenses, the overall power of said plurality of lenses being positive.

8. The system according to claim 7 wherein an exit pupil is positioned between said secondary mirror and said plurality of lenses.

9. The system according to claim 6 wherein the combination of a group of crown-flint lenses and a refractive-diffractive hybrid optical element corrects primary and the secondary axial chromatic aberrations.

10. The system according to claim 6 wherein the combination of a group of crown-flint lenses and a refractive-diffractive hybrid optical element corrects primary and secondary lateral chromatic aberrations.

11. The system according to claim 1 wherein an exit pupil is positioned between said imaging plane and said diffractive optical element.