Optical angle measurement

Patent metadata

Field	Value
Publication number	US-9435641-B2
Application number	US-201313924797-A
Country	US
Kind code	B2
Filing date	Jun 24, 2013
Priority date	Jun 20, 2013
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

An optical detector may include an epitaxial layer having a continuous surface provided on a surface of a substrate. Two or more electrodes may be arranged at different positions in the epitaxial layer so that the electron-hole pairs generated in the epitaxial layer from incident light passing through the aperture and reaching the epitaxial layer have a varying probability of being collected by each of the electrodes as the angle of the incident light changes. The electrodes may be arranged at different depths in the epitaxial layer. The epitaxial layer may be continuous and have a continuous aperture-facing surface between each of the electrodes associated with a particular aperture to ensure that more light passing through the aperture is absorbable in the epitaxial layer and subsequently detectable by the electrodes. This may result in improved light detection capabilities.

First claim

I claim:

1. An optical detector comprising:
a periphery having an aperture;
a substrate having a continuous epitaxial layer with a continuous surface receiving light passing through the aperture; and
a plurality of electrodes, each contacting the epitaxial layer to detect a quantity of the received light;
wherein one of the plurality of electrodes is: (a) positioned at a shallower depth in the epitaxial layer than other ones of the plurality of electrodes and (b) aligned with respect to the aperture to receive the light passing through the aperture.

2. The optical detector of claim 1 , wherein the plurality of electrodes includes two electrodes positioned at equal distances from the aperture and opposite each other.

3. The optical detector of claim 1 , wherein the aperture is a slit.

4. The optical detector of claim 3 , wherein at least two of the electrodes are rectangularly shaped and positioned parallel to the slit aperture at equal distances from the slit aperture.

5. The optical detector of claim 3 , wherein a plurality of the electrodes are point electrodes positioned along a plurality of imaginary lines oriented parallel to the slit aperture.

6. The optical detector of claim 3 , further comprising:
a plurality of slit apertures; and
a pair of electrodes arranged side-by-side on either side of each slit aperture, each electrode detecting a change in its detected quantity of light as the angle of light incident to its respective slit aperture changes.

7. The optical detector of claim 6 , wherein electrodes arranged on a same side of each slit aperture are coupled together to increase light detection efficiency.

8. The optical detector of claim 7 , wherein each of the slit apertures have beveled edges pointing away from the epitaxial layer.

9. The optical detector of claim 7 , wherein each pair of electrodes is centered with a center of its corresponding slit aperture.

10. The optical detector of claim 6 , wherein at least one pair of electrodes is offset from a center of its corresponding slit aperture.

11. The optical detector of claim 1 , wherein each edge of the aperture is beveled.

12. The optical detector of claim 11 , wherein the beveled edges of the aperture are directed away from the epitaxial layer.

13. The optical detector of claim 1 , wherein the aperture is a section of the periphery permeable to light.

14. The optical detector of claim 1 , wherein the periphery is positioned at a height less than 30 microns above the epitaxial layer.

15. The optical detector of claim 1 , wherein the periphery is positioned at a height less than 10 microns above the epitaxial layer.

16. The optical detector of claim 1 , wherein the periphery is positioned directly on top of the epitaxial layer.

17. The optical detector of claim 1 , wherein the periphery has a plurality of apertures, the continuous surface of the epitaxial layer receives light passing through each of the apertures, and the plurality of electrodes includes a set of electrodes for each of the plurality of apertures, each set of electrodes arranged in the epitaxial layer to detect a respective quantity of the received light passing through each respective aperture.

18. The optical detector of claim 17 , wherein at least two of the apertures are slit apertures arranged perpendicular to each other in the optical detector.

19. The optical detector of claim 17 , wherein at least two of the apertures are slit apertures arranged parallel to each other in the optical detector.

20. The optical detector of claim 1 , wherein at least two sections of the periphery are not co-planar with each other.

21. The optical detector of claim 1 , wherein the aperture includes at least three non-parallel and non-perpendicular aperture segments, and the plurality of electrodes includes at least three electrodes, each positioned between different adjacent segments of the aperture.

22. The optical detector of claim 1 , wherein the aperture includes a rhombus aperture and the plurality of electrodes include at least four electrodes, each aligned with a respective side of the rhombus aperture.

23. The optical detector of claim 1 , further comprising a calculation device calculating an angle of the light passing through the aperture from the respective quantities of light detected at each of the electrodes.

24. The optical detector of claim 1 , further comprising a voltage source coupled to the substrate and applying a bias voltage to the epitaxial layer changing a light detection sensitivity of the electrodes.

25. The optical detector of claim 1 , wherein the epitaxial layer is a germanium epitaxial layer.

26. The optical detector of claim 1 , further comprising an isolator to isolate the quantity of light detected by each electrode to only the light passing through the aperture.

27. The optical detectors of claim 26 , wherein the isolator is a trench encompassing the plurality of electrodes.

28. The optical detector of claim 1 , further comprising a medium between the periphery and the epitaxial layer that does not focus light passing through it.

29. The optical detector of claim 28 , wherein the medium is a glass or a polymer.

30. The optical detector of claim 1 , wherein the one of the plurality of electrodes is a central electrode.

31. The optical detector of claim 1 , wherein the one of the plurality of electrodes is positioned in the epitaxial layer at an absorption depth of visible light and the plurality of electrodes are positioned in the epitaxial layer at an absorption depth of near infrared light.

32. The optical detector of claim 1 , further comprising a calculation device calculating a quantity of ambient light from photocurrents obtained from the plurality of electrodes.

33. The optical detector of claim 32 , wherein the calculation device further calculates a characteristic of the received light from the photocurrents obtained from the plurality of electrodes.

34. The optical detector of claim 33 , wherein the characteristic of the received light is a color temperature.

35. The optical detector of claim 1 , further comprising a calculation device calculating a quantity of ambient light from photocurrents obtained from the plurality of electrodes and calculating an angle of the light passing through the aperture from the respective quantities of light detected at each of the plurality of electrodes.

36. An optical detector comprising:
a periphery having a plurality of slit apertures at least two of which are oriented orthogonally to each other;
a substrate having an epitaxial layer receiving light passing through each of the slit apertures; and
a set of electrodes associated with each slit aperture, each electrode in each set arranged in the epitaxial layer to detect a quantity of the received light passing through the respective slit aperture, wherein the epitaxial layer has a continuous surface at least for each set of electrodes that encompasses the electrodes in each respective set of electrodes;
wherein one of the set of electrodes is: (a) positioned at a shallower depth in the epitaxial layer than other electrodes of the set of electrodes and (b) aligned with respect to the slit aperture corresponding to the one of the set of electrodes t

Assignees

• Analog Devices Inc

Inventors

• Deliwala Shrenik

Classifications

• G01C15/004

  Reference lines, planes or sectors · CPC title

• G01C15/002

  Active optical surveying means (optical plumbing G01C15/105) · CPC title

• G01B11/272

  using photoelectric detection means · CPC title

• G01B11/27

  for testing the alignment of axes {(means for centering or aligning a light guide within a ferrule G02B6/3834)} · CPC title

• G01B11/26 Primary

  for measuring angles or tapers; for testing the alignment of axes · CPC title