Spherical illuminator

• US 5,628,559 A
• Filed: 06/07/1995
• Issued: 05/13/1997
• Est. Priority Date: 11/10/1994
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Anderson, Charles H.
• Primary Examiner(s): LEE, Y MY QUACH
• Application Number:
  US08/482,055
• Time in Patent Office: 706 Days
• Field of Search: 362/32, 362/300, 362/355, 362/362, 362/363, 362/298, 362/216, 362/311, 362/346, 356/394, 356/236
• US Class Current: 362/363
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/956 Inspecting patterns on the surface of objects contactless testing of electronic circuits G01R31/308; testing currency G07D; manufacturing processes per se of semiconductor devices implementing a measuring step H01L22/10

Abstract

A spherical illuminator (10, 40, 50, 60) having an upper diffuser (17, 47, 56, 62) with a concave surface, and having either an opposing reflector (18, 41) or an opposing lower diffuser (57, 63) with a concave surface. The two concave surfaces are placed so that their concavities form a substantially spherical viewing area into which the object under inspection is placed. The upper diffuser (10, 40, 50, 60) has a viewing aperture. It transmits light uniformly to the object from approximately two-pi steradians. The reflector (18, 41) or the lower diffuser (57, 63) provides light to the object in another two-pi steradians, resulting in nearly four-pi steradians of illumination.

Claims

1. A spherical illuminator for shadowless illumination of an object under inspection, comprising:

an upper diffuser having a substantially hemispherical surface that is concave such that said surface forms an inner viewing area, said upper diffuser providing transmitted illumination from substantially all of said inner viewing area, and said diffuser having an aperture permitting said object under said diffuser to be viewed from outside said diffuser;

a lower diffuser associated with said upper diffuser having a substantially hemispherical surface that is concave and that opposes the concave surface of said upper diffuser, said lower diffuser providing transmitted illumination from substantially all of said lower diffuser concave surface; and

a housing surrounding said upper diffuser and said lower diffuser.

2. The illuminator of claim 1, wherein said upper diffuser and said lower diffuser are each a hollow hemispherical shell having a diffusive attribute.

3. The illuminator of claim 2, further comprising a reflector opposing at least part of an outer surface of one of said upper and said lower diffusers, said reflector directing light from a source to said one of said lower and upper diffuser.

4. The illuminator of claim 1, wherein said housing comprising an upper housing and a lower housing, said housing having reflective innerwalls so as to reflect light to said concave surfaces.

5. The illuminator of claim 1, further comprising at least one light source providing light to be transmitted through said upper diffuser and said lower diffuser.

6. The illuminator of claim 1, further comprising at least one fiber optic cable ring for providing light to be transmitted through one of said upper diffuser and said lower diffuser.

7. The illuminator of claim 1, further comprising an annular lamp providing light to be transmitted through one of said upper and said lower diffusers.

8. The illuminator of claim 1, wherein said housing has a viewing area.

9. A method of providing shadowless illumination of an object, comprising the steps of:

providing an upper diffuser having a concave and substantially hemispherical surface;

placing a lower diffuser having a concave and substantially hemispherical surface such that said concave surface of said lower diffuser opposes the concave surface of said upper diffuser forming a viewing area;

positioning an object to be illuminated into said viewing area;

directing radiation through said upper diffuser and said lower diffuser so as to distribute radiation within said viewing area from substantially all of the area of said concave surface of said upper diffuser and from substantially all of the area of said concave surface of said lower diffuser.