Chromatic confocal sensor
A sensing device includes an aperture structure having an aperture and imaging optics configured to direct polychromatic light toward the aperture. The imaging optics separates the light according to spectral range longitudinally along a first axis The aperture substantially transmits a spectral range of the light and substantially blocks other spectral ranges of the light. An optical detector is arranged to receive the spectral range of the light that is transmitted through the aperture. The optical detector generate an electrical output that corresponds to a centroid of the spectral range of the light.
1. An optical device, comprising:
an aperture structure having an aperture;
imaging optics configured to direct polychromatic light toward the aperture and to separate the light according to spectral range longitudinally along a first axis, the aperture substantially transmitting a spectral range of the light and substantially blocking other spectral ranges of the light;
an optical detector configured to receive the spectral range of the light that is transmitted through the aperture and to generate an electrical output that corresponds to a centroid of the spectral range of the light.
2. The device of claim 1 , wherein the optical detector comprises:
an optical filter having a laterally varying transmission characteristic with respect to wavelength along a second axis perpendicular to the first axis; and
a photosensor configured to sense a lateral position of the spectral range of the light transmitted through the optical filter and to generate the electrical output, wherein the electrical output is responsive to the lateral position of the spectral range of the light and indicative of the centroid of the spectral range of the light.
3. The device of claim 1 , further comprising a light source that emits the polychromatic light, wherein:
the light source is configured to be attached to a first structural component;
the imaging optics, aperture, and optical detector are attached to a second structural component in a fixed relationship; and
the output of the optical detector varies according to distance between the first member and the second member.
4. The device of claim 1 , further comprising a light source that emits the polychromatic light, wherein:
the light source and the imaging optics are configured to be attached to a first structural component in a fixed relationship;
the aperture, and optical detector are attached to a second structural component in a fixed relationship; and
the output of the optical detector varies according to distance between the first structural component and the second structural component.
5. The device of claim 1 , further comprising a beam splitter disposed between the aperture structure and the imaging optics, the beam splitter arranged to direct the polychromatic light toward the imaging optics, the polychromatic light passing through the imaging optics and to an object, the beam splitter arranged to direct light reflected from the object and passing through the imaging optics toward the aperture structure.
6. The device of claim 1 , wherein distances between two or more of the light source, the imaging optics, and aperture structure change responsive to strain.
7. The device of claim 6 , wherein a length of the imaging optics changes in response to the strain.
8. The device of claim 7 , wherein the imaging optics is a graded index (GRIN) lens.
9. The device of claim 8 , further comprising a light source that emits the polychromatic light, wherein the light source is optically coupled to the GRIN lens by a first light guide.
10. The device of claim 9 , wherein the GRIN lens is optically coupled to the optical filter by a second light guide.
11. The device of claim 10 , wherein at least one of the first and second light guides is an optical fiber.
12. The device of claim 1 , further comprising a light source that emits the polychromatic light, wherein:
the imaging optics comprises a mirror with a lens disposed thereon, the imaging optics arranged such that the polychromatic light is reflected by the mirror and toward the aperture structure; and
the imaging optics is configured to be fixedly attached to a first member;
the light source is configured to be fixedly attached to a second member; and
the output of the optical detector varies according to distance between the first member and the second member.
13. The device of claim 1 , wherein the device is an integrated optoelectronic device.
14. The device of claim 13 , wherein the imaging optics comprises a film comprising:
a first layer having an unstructured surface and a structured surface that includes a first array of lenslets; and
a second layer having an unstructured surface and a structured surface that includes a second array of lenslets, the first and second layers spaced apart from each other.
15. The device of claim 14 , wherein the optical detector is disposed on the film.
16. The device of claim 14 , further comprising a polychromatic light source that generates the polychromatic light, the polychromatic light source disposed on the film.
17. A method, comprising:
separating polychromatic light according into a plurality of spectral ranges longitudinally along a first axis;
transmitting a spectral range of the light through an aperture; and
generating an electrical output that corresponds to a centroid of the spectral range of the light.
18. The method of claim 17 , further comprising measuring a distance between a first structural component and a second structural component based on the electrical output.
19. The method of claim 17 , further comprising measuring vibration of a structural component based on the electrical output.
20. The method of claim 17 , further comprising measuring strain based on the electrical output.