Lens-less optical position measuring sensor

• US 9,702,690 B2
• Filed: 12/19/2011
• Issued: 07/11/2017
• Est. Priority Date: 12/19/2011
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Deliwala, Shrenik
• Primary Examiner(s): LUU, THANH X
• Application Number:
  US13/329,510
• Publication Number:
  US 20130155396A1
• Time in Patent Office: 2,031 Days
• Field of Search: 2502031-2036, 2502061, 356138, 356154
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01B 11/26 for measuring angles or tapers; for testing the alignment of axes
• CPC Class Codes: G01J 1/0242 Control or determination of height or angle information of sensors or receivers; Goniophotometry
• CPC Class Codes: G01J 1/0437 using masks, aperture plates, spatial light modulators, spatial filters, e.g. reflective filters
• CPC Class Codes: G01J 1/1626 Arrangements with two photodetectors, the signals of which are compared

Abstract

An optical detector may include an aperture, at least two photodetectors, and a measuring arrangement to quantify light detected at the photodetectors after passing through the aperture without the need for a lens. The aperture may be positioned between a light source and the two photodetectors to allow light from a light source to pass through the aperture to the photodetectors. The photodetectors may include PIN junction photodiodes and may be electrically isolated from each other, positioned next to each other in a side-by-side configuration, and then aligned with the aperture so that a proportion of the quantified light detected at the photodetectors changes as an angle of light from the light source incident to the aperture changes. Optical detectors and methods are provided.

Claims

1. An integrated circuit for detecting an angle of incident light, comprising:

a surface having apertures;

a plurality of photodetectors arranged in at least three pairs of photodetectors and separated from each other by trenches, each of the pairs of the photodetectors is aligned underneath a respective one of the apertures; and

an optically transparent solid medium disposed between the surface and the plurality of photodetectors,

wherein at least two pairs of the pairs of photodetectors are aligned in a first direction and wherein outputs of corresponding photodetectors of each of the at least two pairs of photodetectors are electrically coupled together in parallel so as to generate aggregated photocurrents that depend on the angle of the incident light in relation to the first direction, with the angle of incident light in relation to the first direction being detectable based on a ratio of the aggregated photocurrents generated by the corresponding photodetectors of the at least two pairs of photodetectors; and

a plurality of opaque barriers disposed in the optically transparent solid medium, wherein each of the at least three pairs of photodetectors is separated from each adjacent pair of photodetectors by one of the plurality of opaque barriers and the pairs of photodetectors that are adjacent to each another are collinear.

2. The integrated circuit of claim 1, wherein the trenches that separate the photodetectors within each pair of the photodetectors are aligned with respective centers of the apertures.

3. The integrated circuit of claim 1, wherein each aperture is a slit.

4. The integrated circuit of claim 1, wherein the apertures have edges and each edge of the apertures is beveled.

5. The integrated circuit of claim 4, wherein the beveled edges are directed away from the photodetectors.

6. The integrated circuit of claim 1, wherein the apertures are sections of the surface that are permeable to light.

7. The integrated circuit of claim 1, wherein the surface is disposed less than 30 microns above the pairs of photodetectors.

8. The integrated circuit of claim 1, wherein the optically transparent solid medium comprises a polymer or a glass.

9. The integrated circuit of claim 1, wherein each of the plurality of opaque barriers is configured to prevent reflected light from reaching photodetectors in an adjacent pair of photodetectors, wherein photodetectors within each pair of photodetectors are optically connected.

10. The integrated circuit of claim 1, further comprising at least two additional pairs of photodetectors aligned in a second direction substantially perpendicular to the first direction.

11. The integrated circuit of claim 10, wherein outputs of corresponding photodetectors of the at least two additional pairs of photodetectors are electrically coupled together in parallel so as to generate an aggregated photocurrent depending on the angle of the incident light in relation to the second direction, with the angle of incident light in relation to the second direction being detectable based on a ratio of the aggregated photocurrents generated by the corresponding photodetectors of the at least two additional pairs of photodetectors.

12. A method for detecting an angle of light incident on an integrated circuit that includes a plurality of electrically isolated photodetectors arranged in at least three pairs, with at least two pairs of the at least three pairs of photodetectors being aligned in a first direction and outputs of corresponding photodetectors of each of the at least two pairs of photodetectors being electrically coupled together in parallel so as to generate aggregated photocurrents, each of the at least three pairs of photodetectors is separated from each adjacent pair of photodetectors by different ones of a plurality of opaque barriers, and the pairs of photodetectors that are adjacent to each another are collinear, the method comprising:

receiving the incident light at the at least two pairs of photodetectors through respective apertures along an optical path without passing through a lens;

combining currents generated by corresponding photodetectors of each of the at least two pairs of photodetectors to produce aggregated photocurrents that depend on the angle of the incident light in relation to the first direction; and

determining the angle of incident light in relation to the first direction based on a ratio of the aggregated photocurrents generated by the corresponding photodetectors of the at least two pairs of photodetectors.

13. The method of claim 12, wherein the integrated circuit comprises at least two additional pairs of photodetectors aligned in a second direction substantially perpendicular to the first direction and wherein outputs of corresponding photodetectors of the at least two additional pairs of photodetectors are electrically coupled together in parallel so as to generate aggregated photocurrents depending on the angle of the incident light relative to the second direction, the method further comprising:

receiving the incident light at the at least two additional pairs of photodetectors through respective apertures along an optical path without passing through a lens;

combining currents generated by corresponding photodetectors of each of the at least two additional pairs of photodetectors to produce aggregated photocurrents that depend on the angle of the incident light relative to the second direction; and

determining the angle of incident light relative to the second direction based on a ratio of the aggregated photocurrents generated by the corresponding photodetectors of the at least two additional pairs of photodetectors.

14. The method of claim 12, further comprising:

blocking, with an opaque barrier disposed in an optically transparent solid medium between adjacent pairs of photodetectors, light reflected from a first pair of photodetectors from reaching an adjacent second pair of photodetectors, and light reflected from the second pair of photodetectors from reaching the first pair of photodetectors.

15. The method of claim 12, wherein the apertures are sections of a surface of the integrated circuit that are permeable to light.

16. The method of claim 12, wherein the apertures are formed as slits.

17. The method of claim 15, wherein the surface is disposed less than 30 microns above the pairs of photodetectors.

18. A lens-less apparatus for detecting an angle of incident light, comprising:

means for electrically isolating photodetectors from each other, the photodetectors being arranged in at least three pairs of photodetectors,

means for optically isolating each of the at least three pairs of photodetectors from adjacent pairs of photodetectors, wherein pairs of photodetectors that are adjacent to each another are collinear;

means for generating aggregated photocurrents from the photodetectors of at least two pairs of photodetectors aligned in a first direction in response to the incident light; and

means for permitting the incident light to reach the means for generating along an optical path without a lens, said optical path extending through an optically transparent solid medium, wherein the angle of incident light in relation to the first direction is detectable based on a ratio of the aggregated photocurrents from the at least two pairs of photodetectors.

19. The apparatus of claim 18, wherein the means for permitting comprise an aperture.

20. The apparatus of claim 19, wherein the aperture is a section of a surface that is permeable to light.

21. The apparatus of claim 19, wherein the aperture is formed as a slit extending perpendicular to the first direction.

22. The apparatus of claim 18, further comprising:

second means for generating aggregated photocurrents from the photodetectors of at least two additional pairs of photodetectors aligned in a second direction in response to the incident light; and

means for permitting the incident light to reach the second means for generating along a second optical path without a lens, said second optical path extending through the optically transparent solid medium, wherein the angle of incident light in relation to the second direction is detectable based on a ratio of the aggregated photocurrents from the at least two additional pairs of photodetectors.

23. The apparatus of claim 20, wherein the means for optically isolating comprises an opaque barrier disposed between the at least two pairs of photodetectors in an optically transparent solid medium arranged between the surface and the photodetectors and configured to prevent reflected light from reaching photodetectors in an adjacent pair of photodetectors.