Apparatus for projecting electromagnetic radiation with a tailored intensity distribution

• US 6,238,077 B1
• Filed: 09/16/1999
• Issued: 05/29/2001
• Est. Priority Date: 01/23/1996
• Status: Expired due to Term

• Current Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Original Assignee: Advanced Optical Technologies, LLC
• Inventors: Rains, Jack C. Jr., Ramer, David P., Crowley, George David III, Bagwell, Richard S.
• Primary Examiner(s): CARIASO, ALAN B
• Application Number:
  US09/397,141
• Time in Patent Office: 621 Days
• Field of Search: 362/551, 362/153, 362/153.1, 362/298, 362/300-305, 362/346, 362/560
• US Class Current: 362/560
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 5/16 using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 5/163 Determination of attitude using inertial means G01C9/00; control of attitude G05D1/49
• CPC Class Codes: G01S 7/4816 of receivers alone

Abstract

The optical system of the present invention efficiently projects electromagnetic radiation such as visible light over a predetermined field of illumination with a tailored intensity distribution. The system includes a base having an optical area that faces the area to be illuminated. The apparatus further includes a mask spaced over the optical area of the base. The system also includes a cavity with an aperture, formed in either the optical area of the base or in a surface of the mask facing toward the base. The base and mask are arranged so that the mask constructively occludes the optical area of the base and/or the aperture of the cavity, with respect to the field of illumination. The system further includes a baffle. The baffle may be between the mask and the base. The baffle may extend into or be within the cavity. The base, the mask, and the baffle have outer surfaces that are reflective, and preferably exhibit a significant diffuse, reflective characteristic. A source emits electromagnetic radiation (e.g., visible light) into the cavity, and the base, mask and baffle redirect this radiation, for illumination of the intended footprint with the tailored intensity distribution. One example of a tailored distribution is a uniform distribution over a hemisphere, or 2π steradians. In another example, the system uniformly illuminates a designated planar surface.

Claims

1. A system for projecting electromagnetic radiation, comprising:

a) a base having a first defined area substantially facing a region to be illuminated with the electromagnetic radiation, the first defined area having a reflective characteristic with respect to the electromagnetic radiation;

b) a mask between the base and the region to be illuminated at a predetermined distance from the defined area of the base, said mask having a defined area substantially facing the defined area of the base and having a reflective characteristic with respect to the electromagnetic radiation;

c) a cavity formed in one of the defined areas, wherein the base, the mask and the cavity define an axis directed toward the area to be illuminated, said cavity comprising an inner surface with a reflective characteristic with respect to the electromagnetic radiation and an opening, a perimeter of the opening of the cavity forming an aperture, wherein the mask is positioned relative to the base and configured so as to occlude electromagnetic radiation emerging from the aperture of the cavity with respect to illumination of the region;

d) a source configured to emit the electromagnetic radiation into the cavity; and

e) a baffle, having a highly diffusely reflective characteristic with respect to the electromagnetic radiation, located between the base and the mask, for increasing intensity of radiation distributed toward peripheral portions of the region to be illuminated.

2. A system as in claim 1, wherein the baffle comprises a cone extending from a broad end adjacent the defined area of the mask to a narrow end towards the defined area of the base.

3. A system as in claim 2, wherein the cavity is formed in the base, and the narrow end of the cone extends substantially to the aperture of the cavity.

4. A system as in claim 1, wherein the baffle comprises a plurality of walls extending radially from the axis dividing a region between base and the mask into sections.

5. A system as in claim 4, wherein the walls divide the region between base and the mask into quadrants.

6. A system as in claim 4, wherein the cavity is formed in the base, and the walls extend substantially from the defined area of the mask to the aperture of the cavity.

7. A system as in claim 4, wherein at least a portion of the walls of the baffle are within the cavity.

8. A system as in claim 1, wherein the baffle is substantially located within the cavity.

9. A system as in claim 8, wherein the baffle comprises a planar surface extending parallel to the aperture about the axis.

10. A system as in claim 9, wherein the baffle further comprises an annular surface, formed at an angle with respect to the planar surface and extending from the planar surface to the inner wall of the cavity.

11. A system as in claim 1, wherein the base, the mask and the aperture are substantially circular.

12. A system as in claim 11, wherein the baffle is substantially circular and has a circular surface generally parallel to the aperture.

13. A system as in claim 11, wherein the base comprises a ring-shaped shoulder surrounding the defined area of the base facing substantially toward the region to be illuminated, the ring-shaped shoulder having a reflective characteristic with respect to the electromagnetic radiation.

14. A system as in claim 1, wherein the defined area of the base, the defined area of the mask and the inner surface of the cavity exhibit a highly diffuse reflectivity with respect to the electromagnetic radiation.

15. A system as in claim 14, wherein the source emits visible light and the highly diffuse reflectivity is with respect to visible light.

16. A system as in claim 1, wherein the base, the mask, the cavity and the baffle are arranged so that the system provides substantially uniform intensity distribution over a range of angles with respect to the axis.

17. A system as in claim 16, wherein the range of angles substantially corresponds to illumination of a hemispherical region.

18. A system as in claim 1, wherein the base, the mask, the cavity and the baffle are arranged so that the system illuminates a predetermined area of a planar surface with a substantially uniform intensity.

19. A system as in claim 1, wherein the cavity is formed in the base and the defined area of the base corresponds to the aperture of the cavity.

20. A system as in claim 1, wherein the inner surface of the cavity corresponds in contour to a segment of a sphere.

21. A system as in claim 20, wherein the inner surface of the cavity is substantially hemispherical.

22. A system as in claim 1, wherein the source comprises an optical fiber coupled to the cavity for supplying the electromagnetic radiation into the cavity.

23. A system as in claim 1, wherein the source comprises a lamp positioned between the mask and the base.

24. A system as in claim 23, wherein the mask comprises a reflector formed around the lamp to reflect electromagnetic radiation from the lamp toward the defined area of the base.

25. A system as in claim 24, wherein the cavity is formed in the defined area of the base.

26. Apparatus for projecting electromagnetic radiation over a predetermined field of illumination with a tailored intensity distribution, comprising:

a base;

a cavity formed in the base, a surface of the cavity having a diffuse reflective characteristic with respect to the electromagnetic radiation, an aperture of the cavity facing toward the predetermined field of illumination;

a mask positioned between the cavity aperture and the predetermined field of illumination to occlude a substantial portion of the cavity aperture with respect to the predetermined field of illumination, a surface of the mask facing the cavity aperture having a diffuse reflective characteristic with respect to the electromagnetic radiation;

a baffle located between the surface of the cavity and the mask surface facing the cavity aperture, having a diffuse reflective characteristic with respect to the electromagnetic radiation, for increasing amount of the electromagnetic radiation projected to outer regions of the predetermined field of illumination; and

a source arranged to emit the electromagnetic radiation substantially into the cavity,

wherein the mask, the cavity and the baffle are configured to tailor an intensity distribution of radiation projected from the system over the field of illumination.

27. An apparatus as in claim 26, wherein the baffle comprises a cone extending from a large end adjacent the mask surface facing the cavity aperture to a narrow end near the aperture.

28. An apparatus as in claim 26, wherein the baffle comprises a plurality of walls extending radially from an axis of the aperture dividing a region between the inner surface of the cavity and the facing surface of the mask into sections.

29. An apparatus as in claim 28, wherein the walls divide the region into quadrants.

30. An apparatus as in claim 28, wherein the walls extend substantially from the facing surface of the mask to the aperture of the cavity.

31. An apparatus as in claim 28, wherein at least a portion of the walls of the baffle are within the cavity.

32. An apparatus as in claim 26, wherein a substantial portion of the baffle is within the cavity.

33. An apparatus as in claim 32, wherein the baffle comprises a diffusely reflective planar surface extending parallel to the aperture.

34. An apparatus as in claim 33, wherein the baffle further comprises a diffusely reflective annular surface, formed at an angle with respect to the planar surface and extending from the planar surface toward the inner wall of the cavity.

35. A lighting system, comprising:

a base having a reflective cavity formed therein, an aperture of the reflective cavity facing toward an area to be illuminated by the system;

a source arranged to emit visible light for reflection within the cavity;

a mask between the aperture and the area to be illuminated by the system, the mask positioned with respect to the aperture to occlude a substantial portion of the aperture with respect to the area to be illuminated by the system, the mask having a surface facing toward the cavity aperture that exhibits a substantially diffuse reflectivity with respect to visible light; and

a baffle positioned at least partially within the cavity, the baffle having a substantially diffuse reflectivity with respect to visible light, wherein the baffle directs at least some of the visible light outward for increasing light projected from the system to outer regions of the area to be illuminated.

36. A lighting system as in claim 35, wherein the baffle comprises a reflective central surface about a central axis of the cavity and the aperture.

37. A lighting system as in claim 36, wherein the central surface is substantially planar and is parallel to the cavity aperture.

38. A lighting system as in claim 36, wherein the baffle further comprises a reflective annular bevel around at least a portion of the central surface.