Remote position sensing apparatus and method

• US 5,757,478 A
• Filed: 06/03/1996
• Issued: 05/26/1998
• Est. Priority Date: 06/03/1996
• Status: Expired due to Fees

• Current Assignee: Chris Chen-Hsing Ma
• Original Assignee: Chris Chen-Hsing Ma
• Inventors: Ma, Chris Chen-Hsing
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US08/655,082
• Time in Patent Office: 722 Days
• Field of Search: 356/141.2, 356/141.3, 356/141.5
• US Class Current: 356/141.2
• CPC Class Codes: G01S 3/781 Details
• CPC Class Codes: G01S 3/784 using a mosaic of detectors

Abstract

A sensor for determining a one-dimensional component of the angular orientation of a radiation source relative to the sensor has a radiation sensitive element which produces an electrical signal representative of radiation incidence upon the element. A radiation-opaque mask is mounted between the element and the radiation source. A first plurality of parallel slit apertures are provided in the mask. The slits are spaced relative to one another, and the element is aligned relative to the mask, such that radiation emitted by the source through at least one of the slits is simultaneously incident upon at least two independent radiation-sensitive points on the element while the source is within an intended operational range of the sensor; and, the points are displaced from the one slit by different distances.

Claims

1. A sensor for determining a one-dimensional component of the angular orientation of a radiation source relative to said sensor, comprising:

(a) a radiation sensitive element for producing an electrical signal representative of radiation incidence upon said element;

(b) a radiation-opaque mask mounted between said element and said radiation source, said mask having a first plurality of parallel rows of one or more longitudinally aligned, narrow width apertures;

wherein;

(i) said rows of apertures are spaced relative to one another, and said element is aligned relative to said mask, such that radiation emitted by said source through at least one of said rows of apertures is simultaneously incident upon at least two independent radiation-sensitive points on said element while said source is within an intended operational range of said sensor; and

,

(ii) said points are displaced from said one of said rows of apertures by different distances.

2. A sensor as defined in claim 1, wherein said rows of apertures lie in a first plane.

3. A sensor as defined in claim 2, wherein said rows of apertures are equally spaced.

4. A sensor as defined in claim 1, wherein said parallel rows of apertures lie in a symmetric rectilinear surface shaped to intersect a plurality of planes perpendicularly, said planes extending from a radiation sensitive point on said element through said rows of apertures.

5. A sensor as defined in claim 4, wherein:

(a) said surface is hemi-cylindrical; and

,

(b) adjacent rows of said apertures on said surface are spaced apart by amounts which vary in inverse proportion to distance along said surface between said adjacent rows and an arc centre of said surface.

6. A sensor as defined in claim 1, wherein said radiation source is a point light source, and said radiation sensitive element is a position sensitive photo-sensor.

7. A sensor as defined in claim 1, wherein:

(a) said radiation sensitive element comprises first and second radiation sensitive segments respectively extending in separate, non-intersecting planes which do not intersect said mask; and

,

(b) at least one of said points is on said first segment and at least one of said points is on said second segment.

8. A sensor as defined in claim 1, wherein said element lies in a plane inclined with respect to said rows of apertures about an axis perpendicular to said rows of apertures.

9. A sensor as defined in claim 8, wherein:

(a) said element comprises first and second non-intersecting, radiation sensitive segments; and

,

(b) at least one of said points is on said first segment and at least one of said points is on said second segment.

10. A sensor as defined in claim 7, wherein said parallel rows of apertures lie in a symmetric rectilinear surface shaped to intersect a plurality of planes perpendicularly, said planes extending from a radiation sensitive point on said element through said rows of apertures.

11. A sensor as defined in claim 10, wherein adjacent rows of said apertures on said surface are spaced apart by amounts which vary in inverse proportion to distance along said surface between said adjacent rows and an arc centre of said surface.

12. A sensor for determining a one-dimensional component of the angular orientation of a radiation source relative to said sensor, comprising:

(a) a radiation sensitive element for producing an electrical signal representative of radiation incidence upon said element;

(b) a radiation-opaque mask mounted between said element and said radiation source, said mask having a first plurality of parallel rows of one or more longitudinally aligned, narrow width apertures;

(c) a high refractive index cover overlying at least a portion of said element;

wherein;

(i) said element lies in a plane parallel to said rows of apertures and separated from said mask;

(ii) said element and said cover are aligned, relative to said mask, such that radiation emitted by said source through at least one of said rows of apertures is simultaneously incident upon at least two independent radiation-sensitive points on said element while said source is within an intended operational range of said sensor;

(iii) at least one of said points is under said cover; and

,

(iv) at least one of said points is not under said cover.

13. A sensor as defined in claim 12, wherein said parallel rows of apertures lie in a symmetric rectilinear surface shaped to intersect a plurality of planes perpendicularly, said planes extending from a radiation sensitive point on said element through said rows of apertures.

14. A sensor as defined in claim 13, wherein adjacent rows of said apertures are spaced apart by amounts which vary in inverse proportion to distance along said surface between said adjacent rows and an arc centre of said surface.

15. A sensor for determining two one-dimensional components of the angular orientation of a radiation source relative to said sensor, comprising:

(a) a radiation sensitive element for producing an electrical signal representative of radiation incidence upon said element;

(b) a radiation-opaque mask mounted between said element and said radiation source, said mask having a first plurality of parallel rows of one or more longitudinally aligned, narrow width apertures lying in a first plane and, a second plurality of parallel rows of one or more longitudinally aligned, narrow width apertures lying in said first plane and extending perpendicular to said first plurality of rows of apertures;

wherein;

(i) said element lies in a second plane inclined with respect to said first plane about an axis perpendicular to said first plurality of rows of apertures and further inclined with respect to an axis perpendicular to said second plurality of rows of apertures;

(ii) said first plurality of rows of apertures are spaced relative to one another, said second plurality of rows of apertures are spaced relative to one another, and said element is aligned relative to said mask, such that;

(A) radiation emitted by said source through at least one of said first plurality of rows of apertures is simultaneously incident upon at least two independent radiation-sensitive first points on said element while said source is within an intended operational range of said sensor;

(B) radiation emitted by said source through at least one of said second plurality of rows of apertures is simultaneously incident upon at least two independent radiation-sensitive second points on said element while said source is within an intended operational range of said sensor;

(iii) said first points are displaced from said one first plurality row by different distances; and

,

(iv) said second points are displaced from said one second plurality row by different distances.

16. A sensor for determining two one-dimensional components of the angular orientation of a radiation source relative to said sensor, comprising:

(a) a radiation sensitive element lying in a first plane, said element notionally divided into four quadrants by first and second mutually perpendicular axes, said element for producing an electrical signal representative of radiation incidence upon said element;

(b) a radiation-opaque mask mounted between said element and said radiation source, said mask having a first plurality of parallel rows of one or more longitudinally aligned, narrow width apertures extending parallel to said first axis and lying in a second plane, and a second plurality of parallel rows of one or more longitudinally aligned, narrow width apertures extending perpendicular to said first plurality of rows of apertures;

(c) a high refractive index cover overlying at least one of said quadrants;

wherein;

(i) said first and second planes are parallel;

(ii) said first plurality of rows of apertures are spaced relative to one another and said element is aligned relative to said mask, such that radiation emitted by said source through at least one of said first plurality of rows of apertures is simultaneously incident upon at least two independent radiation-sensitive first points on said element while said source is within an intended operational range of said sensor, with at least one of said first points under said cover and at least one of said first points not under said cover; and

,

(iii) said second plurality of rows of apertures are spaced relative to one another and said element is further aligned relative to said mask, such that radiation emitted by said source through at least one of said second plurality of rows of apertures is simultaneously incident upon at least two independent radiation-sensitive second points on said element while said source is within an intended operational range of said sensor, with at least one of said second points under said cover and at least one of said second points not under said cover.

17. A sensor for determining two one-dimensional components of the angular orientation of a radiation source relative to said sensor, comprising:

(a) first and second radiation sensitive elements respectively lying in first and second non-intersecting planes, said elements for producing electrical signals representative of radiation incidence upon said respective elements;

(b) a radiation-opaque mask mounted between said elements and said radiation source, said mask having a first plurality of parallel rows of one or more longitudinally aligned, narrow width apertures lying in a third plane not interesecting said first or second planes, and a second plurality of parallel rows of one or more longitudinally aligned, narrow width apertures lying in said third plane and extending perpendicular to said first plurality of rows of apertures;

wherein;

(i) said first and second planes are separated from said third plane by different distances;

(ii) said first plurality of rows of apertures are spaced relative to one another and said elements are aligned relative to said mask, such that radiation emitted by said source through at least one of said first plurality of rows of apertures is simultaneously incident upon at least two independent radiation-sensitive first points while said source is within an intended operational range of said sensor, with at least one of said first points on said first element and at least one of said first points on said second element; and

,

(iii) said second plurality of rows of apertures are spaced relative to one another and said element are further aligned relative to said mask, such that radiation emitted by said source through at least one of said second plurality of rows of apertures is simultaneously incident upon at least two independent radiation-sensitive second points while said source is within an intended operational range of said sensor, with at least one of said second points on said first element and at least one of said second points on said second element.

18. A sensor for determining a one-dimensional component of the angular orientation of a radiation source relative to said sensor, comprising:

(a) a radiation sensitive element lying in a first plane, said element for producing an electrical signal representative of radiation incidence upon said element;

(b) a radiation-opaque mask mounted between said element and said radiation source, said mask having a plurality of parallel rows of one or more longitudinally aligned, narrow width apertures lying in a second plane;

wherein;

(i) said first plane is parallel to said rows of apertures;

(ii) said element is aligned relative to said mask, and adjacent ones of said rows of apertures are separated, such that radiation emitted by said source through at least three adjacent ones of said rows of apertures is simultaneously incident upon at least three independent radiation-sensitive points on said element while said source is within an intended operational range of said sensor; and

,

(iii) for any adjacent three of said rows of apertures, the ratio of;

(A) distance between a first outward and a central one of said three rows;

to,

(B) distance between a second outward and said central one of said three rows;

is different than said ratio for any other adjacent three of said rows.

19. A sensor for determining two one-dimensional components of the angular orientation of a radiation source relative to said sensor, comprising:

(a) a radiation sensitive element lying in a first plane, said element for producing an electrical signal representative of radiation incidence upon said element;

(b) a radiation-opaque mask mounted between said element and said radiation source, said mask having a first plurality of parallel rows of one or more longitudinally aligned, narrow width apertures lying in a second plane and, a second plurality of parallel rows of one or more longitudinally aligned, narrow width apertures lying in said first plane and extending perpendicular to said first plurality of rows of apertures;

wherein;

(i) said first and second planes are parallel;

(ii) said element is aligned relative to said mask, and adjacent ones of said first plurality of rows of apertures are separated, such that radiation emitted by said source through at least three adjacent ones of said first plurality of rows of apertures is simultaneously incident upon at least three independent radiation-sensitive first points on said element while said source is within an intended operational range of said sensor;

(iii) said element is further aligned relative to said mask, and adjacent ones of said second plurality of rows of apertures are separated, such that radiation emitted by said source through at least three adjacent ones of said second plurality of rows of apertures is simultaneously incident upon at least three independent radiation-sensitive second points on said element while said source is within an intended operational range of said sensor;

(iv) for any adjacent three of said first plurality of rows of apertures, the ratio of;

(A) distance between a first outward and a central one of said three first plurality rows;

to,

(B) distance between a second outward and said central one of said three first plurality rows;

is different than said ratio for any other adjacent three of said first plurality rows; and

,

(v) for any adjacent three of said second plurality of rows, the ratio of;

(A) distance between a first outward and a central one of said three second plurality rows;

to,

(B) distance between a second outward and said central one of said three second plurality rows;

is different than said ratio for any other adjacent three of said second plurality rows.

20. A method of identifying, within a plurality of parallel rows of one or more longitudinally aligned, narrow width apertures in a radiation-opaque mask separating a radiation source from a reference plane, one of said rows through which radiation emitted by said source is incident upon at least two independent points on a radiation sensitive element positioned between said mask and said reference plane, said points at different distances from said reference plane, said method comprising the steps of:

(a) for each one of said rows, predetermining a range of angles for which radiation emitted by said source passes through said one row and is incident upon said element;

(b) for any two of said points;

(i) deriving an angle θ

=arctan(SID/HT) where SID is the distance vector between said points in a direction parallel to said reference plane and perpendicular to said rows of apertures, and HT is the distance vector between said points in a direction perpendicular to said reference plane;

(ii) comparing said deduced angle θ

with said predetermined range of angles; and

,

(iii) selecting, as said one row through which radiation emitted by said source is incident upon said element, that one of said rows for which said predetermined range of angles contains said deduced angle θ

.

21. A method of identifying, within a plurality of parallel rows of one or more longitudinally aligned, narrow width apertures in a radiation-opaque mask separating a radiation source from a reference plane, one of said rows through which radiation emitted by said source is incident upon at least two independent points on a radiation sensitive element positioned between said mask and said reference plane, said method comprising the steps of:

(a) for each one of said rows, predetermining a range of values of distance vectors in a direction parallel to said reference plane and perpendicular to said rows of apertures for which radiation emitted by said source passes through said one row and is incident upon said element; and

,

(b) for any two of said points;

(i) deriving the distance vector between said points in a direction parallel to said reference plane and perpendicular to said rows;

(ii) comparing said derived distance vector with said predetermined range of values; and

,

(c) selecting, as said one row through which radiation emitted by said source is incident upon said element, that one of said rows for which said predetermined range of values contains said derived distance vector.

22. A method of identifying, within a plurality of parallel rows of one or more longitudinally aligned, narrow width apertures in a radiation-opaque mask separating a radiation source from a reference plane, three of said rows through which radiation emitted by said source is incident upon at least first, second and third independent points on a radiation sensitive element positioned between said mask and said reference plane, said mask constructed such that for any adjacent three of said rows, the ratio of:

(i) distance between a first outward and a central one of said three rows;

to,

(ii) distance between a second outward and said central one of said three rows;

is predetermined and different than said ratio for any other adjacent three of said rows, said method comprising the steps of;

(a) determining the distance D_1-2 between said first and second points in a direction parallel to said reference plane and perpendicular to a longitudinal axis of said rows of apertures;

(b) determining the distance D_2-3 between said second and third points in said direction parallel to said reference plane and perpendicular to a longitudinal axis of said rows of apertures;

(c) deriving a distance ratio R=D_1-2 /D_2-3 ;

(d) selecting, as said three rows through which radiation emitted by said source is incident upon said element, those three of said rows for which said predetermined ratio is closest to said ratio R.