System for frontal illumination

• US 5,367,439 A
• Filed: 12/24/1992
• Issued: 11/22/1994
• Est. Priority Date: 12/24/1992
• Status: Expired due to Term

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: Mayer, Ralph D., Fitzgerald, Clifford T., Picard, Len L.
• Primary Examiner(s): Jones, Larry
• Application Number:
  US07/997,767
• Time in Patent Office: 698 Days
• Field of Search: 362/32, 362/302, 362/804, 362/252, 362/33, 362/5, 362/18, 356/1, 356/376
• US Class Current: 362/551
• CPC Class Codes: F21V 7/04 Optical design
• CPC Class Codes: F21W 2131/402 for working places
• CPC Class Codes: G02B 6/0008 the light being emitted at the end of the fibre
• CPC Class Codes: Y10S 362/804 Surgical or dental spotlight

Abstract

A frontal illumination system includes a light source and a finite plurality of reflecting surfaces. The reflecting surfaces can be characterized as the inner surfaces of a set of conical frustums arranged to approximate the illumination coming from the inner surface of a hemisphere. The light source is located within or adjacent to at least one of the reflecting surfaces. It emits light that is reflected off opposing portions of at least one, and preferably all, of the surfaces. The system is capable of illuminating the object from a very large solid angle, even though it is disposed in a substantially short axial space.

Claims

1. An optical-mechanical apparatus for reflecting illuminating radiation onto an object, said apparatus comprising

A. a finite plurality of reflecting surfaces arranged for reflecting at least a portion of said radiation onto said object,

B. each said reflecting surface being characterized as an inner surface of a conical frustum, or portion thereof, opening toward said object, the cross-sectional centers of which are substantially aligned along an axis perpendicular to a viewing plane of said object, and

C. light source means, disposed substantially adjacent to a cross-sectional plane of at least one of said reflecting surfaces, for generating illuminating radiation for reflection off at least a portion of at least one of said reflecting surfaces.

2. An apparatus according to claim 1, wherein each respective conical frustum surface, or portion thereof, is characterized by each said respective surface being sequentially characterized by a respective increasing distance relative to said object, and a respective decreasing angle of reflection with respect to said viewing plane of said object.

3. An apparatus according to claim 2, wherein each said reflecting surface comprises an inner surface of substantially an entire conical frustum.

4. An apparatus according to claim 3, wherein said light source means is disposed within at least one of said reflecting surfaces.

5. An apparatus according to claim 4, wherein said light source means comprises a plurality of illuminating radiation-generating portals, each arranged for generating illuminating radiation for reflection off an opposing portion of at least one of said reflecting surfaces.

6. An apparatus according to claim 5, wherein said reflecting surfaces are arranged to subtend a dispersion angle of said light source means.

7. An apparatus according to claim 6, comprising

A. remote radiation-generating means for generating said illuminating radiation, and

B. fiber optic means, coupled to said remote radiation-generating means, for transmitting that radiation to said light source means.

8. An apparatus according to claim 1, wherein said reflecting surfaces are arranged to define an aperture through which radiation reflected off said object may be detected.

9. An apparatus according to claim 8, comprising central illuminating means for passing radiation through said aperture for further illumination of said object.

10. An apparatus according to claim 9, wherein said central illuminating means illuminates said object at an angle not otherwise illuminated by said reflecting surfaces.

11. An apparatus according to claim 1, wherein

A. said central illuminating means is displaced from said plural reflecting surfaces, and wherein said plural reflecting surfaces are disposed between said central illuminating means and said object,

B. said apparatus further comprises beam-splitter means, disposed between said central illuminating means and said plural reflecting surfaces, for

i) passing at least a portion of the radiation generated by said central illuminating means to said object, and

ii) reflecting at least a portion of the radiation reflected from said object for detection.

12. An apparatus according to claim 11, wherein said light source means generates radiation in the visible spectrum.

13. An apparatus according to claim 11 wherein said detection means comprises a photoreceptor.

14. An optical-mechanical apparatus for large-angle, close-quarters illumination of an object, said apparatus comprising

A. first light source means for generating illuminating radiation,

B. a finite plurality of reflecting surfaces arranged for reflecting at least a portion of that radiation onto said object,

said reflecting surfaces being characterized as inner surfaces of respective conical frustums opening toward said object, the cross-sectional centers of which are substantially aligned along an axis perpendicular to a viewing plane of said object,

C. said reflecting surfaces being arranged to define an aperture through which radiation reflected off said object may be detected,

D. second light source means, comprising an extended illumination source, for passing radiation through said aperture for further illumination of said object, and

E. whereby said object is illuminated as if by a spatially continuous, large-angle source approaching a 180°

included solid angle.

15. An optical-mechanical apparatus for reflecting illuminating radiation onto an object, said apparatus comprising

A. a finite plurality of reflecting surfaces arranged for reflecting at least a portion of said radiation onto said object, said reflecting surfaces being arranged to define an aperture through which radiation reflected off said object may be detected,

B. each said reflecting surface being characterized as an inner surface of a conical frustum, or portion thereof, the cross-sectional centers of which are substantially aligned along an axis perpendicular to a viewing plane of said object,

C. light source means, disposed substantially adjacent to a cross-sectional plane of at least one of said reflecting surfaces, for generating illuminating radiation for reflection off at least a portion of at least one of said reflecting surfaces,

D. central illuminating means for passing radiation through said aperture for further illumination of said object at an angle not otherwise illuminated by said reflecting surfaces, and

E. beam-splitter means, disposed between said central illuminating means and said plural reflecting surfaces, for

i) passing at least a portion of the radiation generated by said central illuminating means to said object, and

ii) reflecting at least a portion of the radiation reflected from said object for subsequent detection.

16. An apparatus according to claim 15, wherein said light source means generates radiation in the visible spectrum.

17. An apparatus according to claim 15 wherein said detection means comprises a photoreceptor.