Single element hemispherical light detector

• US 5,886,351 A
• Filed: 02/20/1998
• Issued: 03/23/1999
• 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.
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): PYO, KEVIN K
• Application Number:
  US09/027,200
• Time in Patent Office: 396 Days
• Field of Search: 250/228, 250/216, 356/236
• US Class Current: 250/228
• CPC Class Codes: G01J 1/04 Optical or mechanical part supplementary adjustable parts
• CPC Class Codes: G01J 1/0437 using masks, aperture plates, spatial light modulators, spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 2001/0481 Preset integrating sphere or cavity
• 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 3/781 Details
• 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

A single element hemispherical light detector that employs the concept of constructed occlusion to improve its uniformity of detection response across a large range of incident angles, and that incorporates a deflector to provide detection response to low incidence angles. The hemispherical light detector uses one active element or photodiode to achieve a substantially uniform response within a sector of a hemisphere.

Claims

1. A light detector that provides a response signal based on the intensity of light incident from any direction within a predetermined sector, comprising:

a base having a surface formed of a diffusely reflective material that defines a reflective region that faces the predetermined sector;

a mask spaced a predetermined distance from the reflective region and located between the base and the predetermined sector such that, when light is incident at an angle normal to the base surface, the mask occludes a portion of the reflective region; and

a sensor, responsive to incident light, that generates the response signal based on the intensity of light that it receives and that is located to intercept light reflections from the base surface,

wherein the base surface, the mask and the sensor are configured such that response of the light detector is substantially uniform independent of the cosine of the angle of incidence of light received from within the predetermined sector.

2. A light detector as defined in claim 1, wherein the reflective region further includes a hemispherical cavity and the reflective region is defined by the cavity'"'"'s aperture.

3. A light detector as defined in claim 2, wherein the mask is a circular disk having at least one flat surface and an axis through the flat surface'"'"'s center that is aligned with an axis through the center of the hemispherical cavity such that the disk'"'"'s flat surface is parallel with the cavity'"'"'s aperture.

4. A light detector as defined in claim 2, further comprising a deflector that reflectively directs light incident from a direction nearly parallel with the aperture toward the reflective region.

5. A light detector that provides a response signal based on the intensity of light incident from any direction within a predetermined sector, comprising:

a base having a surface formed of a diffusely reflective material, the surface having a cavity formed therein, wherein an aperture of the cavity defines a reflective region that faces the predetermined sector; and

a mask spaced a predetermined distance from the reflective region and located between the base and the predetermined sector such that, when light is incident at an angle normal to the base'"'"'s surface, the mask occludes a portion of the reflective region;

a sensor, responsive to incident light, that generates the response signal based on the intensity of light that it receives and that is located to intercept light reflections from the base surface, wherein the base, mask and sensor are configured such that the light detector is substantially uniformly responsive to light from any direction within the predetermined sector,

wherein the mask is configured as a disk whose diameter is about 90% of the diameter of the reflective region.

6. A light detector that provides a response signal based on the intensity of light incident from any direction within a predetermined sector, comprising:

a base having a diffusely reflective cavity, an aperture of the cavity defining a reflective region that faces the predetermined sector;

a mask spaced a predetermined distance from the reflective region and located between the base and the predetermined sector such that, when light is incident at an angle normal to the base'"'"'s surface, the mask occludes a portion of the reflective region; and

a sensor, responsive to incident light, that generates the response signal based on the intensity of light that it receives and that is located to intercept light reflections from the base surface, wherein the base, mask and sensor are configured such that the light detector is substantially uniformly responsive to light from any direction within the predetermined sector,

wherein the mask is spaced away from the reflective region at a distance that is about 10% to 15% of the diameter of the reflective region.

7. A light detector detecting light incident from any direction within a predetermined sector, comprising:

a base configured with a cavity having an aperture defining a light passage region facing the predetermined sector;

a mask spaced a predetermined distance from said light passage region such that, when light is incident at an angle ranging between substantially normal and approaching parallel to said light passage region, the mask occludes a portion of the light passage region;

a deflector positioned between said mask and the aperture defining said light passage region, to redirect light from an angle nearly parallel with said light passage region through the aperture defining said light passage region; and

a sensor responsive to at least a portion of light passing through said light passage region, wherein the light detector is substantially uniformly responsive to light from any direction with the predetermined sector.

8. Alight detector in accordance with claim 7, wherein said base has a surface formed of a diffusely reflective material.

9. A light detector in accordance with claim 7, wherein said deflector is configured with a center portion and said sensor is positioned in said center portion.

10. A light detector in accordance with claim 7, wherein said sensor is positioned to be responsive to light reflected through said light passage region.

11. A light detector in accordance with claim 7, wherein said sensor is positioned to be responsive to light from said light passage region.

12. A radiation detector that provides a response signal based on the intensity of radiation incident from any direction within a predetermined sector, comprising:

a base comprising a diffusely reflective cavity with an aperture configured to define a radiation passage region facing the predetermined sector;

a mask spaced a predetermined distance from and being of a predetermined dimension relative to said radiation passage region defined by the aperture such that, when radiation is incident at an angle ranging between substantially normal and approaching parallel to said radiation passage region, the mask occludes a portion of the radiation passage region defined by the aperture;

a sensor that generates a response signal based on the intensity of radiation that it receives, said sensor responsive to at least a portion of radiation passing through said radiation passage region,

wherein the occlusion of the radiation passage region by the mask causes the radiation detector to be substantially uniformly responsive to radiation received from within the predetermined sector independent of the cosine of the angle of incidence of the received radiation.

13. A radiation detector in accordance with claim 12, wherein said sensor is positioned to respond to radiation reflecting from said cavity through said aperture.

14. A light detector for providing a response signal based on the intensity of light incident from any direction within a predetermined field of view, comprising:

a base having a surface formed of a reflective material that defines a reflective region for facing toward the predetermined sector;

a mask spaced a predetermined distance from the reflective region of the base, said mask comprising a reflective surface substantially facing toward the reflective region of the base;

a cavity comprising at least one diffusely reflective surface, the cavity being formed in one of the reflective region of the base and the reflective surface of the mask; and

a sensor responsive to incident light for generating the response signal based on the intensity of light that it receives, the sensor being coupled to the cavity so as to receive light from within the cavity,

wherein the mask is located between the base and the predetermined field of view such that the mask constructively occludes light incident to the detector from within the field of view with respect to the reflective region of the base and with respect to the cavity, so as to tailor response of the light detector to the incident light in a predetermined manner.

15. A light detector as in claim 14, wherein the cavity comprises a segment of a sphere, and an edge of the segment defines said one of the reflective region of the base and the reflective surface of the mask.

16. A light detector as in claim 15, wherein the segment comprises a hemisphere.

17. A light detector as in claim 14, wherein the base, the mask and the cavity are arranged such that the tailored response of the light detector to the incident light is substantially uniform with respect to angle of incidence over a range of angle within the field of view and around a central axis of the detector.

18. A light detector as in claim 17, wherein the base, the mask and the cavity are arranged such that the tailored response of the light detector to the incident light is substantially uniform independent of the cosine of the angle of incidence of light received from within the range of angels in the predetermined field of view.

19. A light detector as in claim 14, further comprising a deflector positioned between the reflective region of the base and the reflective surface of the mask, for directing light through an opening of the cavity from angles of incidence extending out nearly parallel to the opening.

20. A radiant energy detector for providing a response signal based on the intensity of radiant energy incident from within a predetermined field of view, comprising:

a base having a first surface having a characteristic that is reflective with respect to the radiant energy, the first reflective surface facing substantially toward the predetermined field of view;

a mask having a second surface having a characteristic that is reflective with respect to the radiant energy, the second reflective surface facing substantially toward the first reflective surface;

a cavity comprising a diffusely reflective surface characteristic with respect to the radiant energy and having a defined opening, the cavity being formed in one of the first and second reflective surfaces; and

a sensor, coupled to the cavity to receive radiant energy from within the cavity, for generating a response signal based on intensity of the received radiant energy,

wherein the mask is arranged outside the base in such a position as to occluded the opening of the cavity with respect to the radiant energy incident from within the predetermined field of view and in such a manner that the radiant energy detector exhibits a predetermined response characteristic with respect to the incident radiant energy over a range of angles of incidence.

21. A detector as in claim 20, wherein the cavity comprises a segment of a sphere and an edge of the segment defines the opening.

22. A detector as in claim 21, wherein the segment comprises a hemisphere.

23. A detector as in claim 20, wherein the opening is substantially circular, the mask is substantially circular, and a central axis of the substantially circular mask is aligned with a central axis of the substantially circular opening.