Tuning optical cavities

• US 20080186508A1
• Filed: 02/05/2007
• Published: 08/07/2008
• Est. Priority Date: 02/05/2007
• Status: Active Grant

• Current Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Original Assignee: Palo Alto Research Center, Inc. (Xerox Holdings Corp.)
• Inventors: Kiesel, Peter, Bassler, Michael, Schmidt, Oliver, Srinivasan, Uma
• Granted Patent: US 7,633,629 B2
• Time in Patent Office: Days
• US Class Current: 356/519
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G01N 2021/451 for determining the optical absorption
• CPC Class Codes: G01N 21/45 using interferometric methods; using Schlieren methods
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26

Abstract

A tunable optical cavity can be tuned by relative movement between two reflection surfaces, such as by deforming elastomer spacers connected between mirrors or other light-reflective components that include the reflection surfaces. The optical cavity structure includes an analyte region in its light-transmissive region, and presence of analyte in the analyte region affects output light when the optical cavity is tuned to a set of positions. Electrodes that cause deformation of the spacers can also be used to capacitively sense the distance between them. Control circuitry that provides tuning signals can cause continuous movement across a range of positions, allowing continuous photosensing of analyte-affected output light by a detector.

Claims

1. A device comprising:

a tunable optical cavity structure that includes a light-transmissive region between first and second inward reflection surfaces and whose optical cavity operation can be tuned by relative movement between the first and second inward reflection surfaces;

the optical cavity structure including;

an analyte region that can contain analyte within the light-transmissive region, presence of the analyte in the analyte region affecting the optical cavity'"'"'s output light when the optical cavity structure'"'"'s operation is tuned to a set of relative positions of the inward reflection surfaces; and

a tuning structure that can tune the tunable optical cavity structure to at least one of the set of relative positions.

2. The device of claim 1 in which the optical cavity structure further includes:

first and second light-reflective components that include the first and second reflection surfaces, respectively;

the tuning structure including;

one or more deformable components connected to move the first and second light-reflective components, moving the first and second reflection surfaces between relative positions in the set.

3. The device of claim 2 in which each deformable component is elastically deformable.

4. The device of claim 1 in which the set of relative positions includes a range of continuously varying relative positions;

the tuning structure being capable of tuning the optical cavity structure continuously across the range.

5. The device of claim 4 in which the optical cavity provides analyte-affected output light while the tuning structure tunes the optical cavity structure continuously across the range, the output light indicating continuous values of an optical characteristic of the analyte across a range of photon energies.

6. The device of claim 5 in which the optical characteristic is one of refractive index and absorption coefficient.

7. A system comprising the device of claim 1 in which the tuning structure can change the relative positions of the reflection surfaces at a tuning frequency, the system further comprising:

a photosensing component that, in response to control signals, photosenses the optical cavity'"'"'s output light and provides sensing results with a readout frequency; and

control circuitry that provides tuning signals to the tuning structure and control signals to the photosensing component that lock in the tuning frequency and the readout frequency.

8. A method of using the device of claim 1, the method comprising:

tuning the device'"'"'s tunable optical cavity structure;

the act of tuning the tunable optical cavity structure comprising;

tuning the optical cavity continuously across a range of relative positions in the set.

9. The method of claim 8, further comprising:

fluidically carrying the analyte into the analyte region using at least one of a liquid, a gas, and an aerosol.

10. A method of producing a device as in claim 1, the method comprising:

producing the optical cavity structure so that it includes an analyte region that can contain analyte within the light-transmissive region, presence of the analyte in the analyte region affecting the optical cavity'"'"'s output light when the tuning structure tunes the optical cavity structure within the set of relative positions.

11. An optical cavity device comprising:

first and second light-reflective components with a light-transmissive region between them, each of the light-reflective components being able to reflect light into the light-transmissive region;

a tuning structure that, in response to tuning signals, can move the first and second reflective components to any of a set of positions relative to each other;

the tuning structure including;

one or more deformable components connected so that deformation of at least one of the deformable components causes the first and second reflective components to move within the set of positions; and

at least one signal-responsive component that receives the tuning signals and, in response, causes deformation of at least one of the deformable components;

the light-transmissive region including an analyte region, the analyte region being capable of having an analyte in it;

the set of positions including a subset of one or more positions in which the first and second reflective components and the light-transmissive region with analyte in the analyte region can operate as an optical cavity that provides analyte-affected output light, the analyte-affected output light including information about one or more optical characteristics of the analyte.

12. The device of claim 11 in which each deformable component is elastically deformable.

13. The device of claim 11 in which the analyte region is defined in one of the deformable components.

14. The device of claim 11 in which the first and second light-reflective components include first and second facing surfaces, respectively, the first and second facing surfaces each having a respective reflective coating.

15. The device of claim 11 in which the deformable component includes one or more elastomer spacers between the first and second light-reflective components.

16. The device of claim 15 in which the elastomer spacers include poly-di-methyl-siloxane.

17. The device of claim 15 in which the elastomer spacers include electroactive elastomer material.

18. The device of claim 15 in which the analyte region is bounded by the elastomer spacers.

19. The device of claim 15 in which the analyte region is a channel through which analyte can be fluidically carried.

20. The device of claim 11 in which the tuning structure further includes:

one or more sensing components that can provide shape sense signals indicating shape of one of the deformable components.

21. The device of claim 11 in which the signal-responsive components include:

first and second electrodes connected to opposite surfaces of one of the deformable components.

22. The device of claim 11 in which the analyte-affected output light has a laterally varying intensity distribution.

23. The device of claim 11 in which the optical cavity provides output light at an exit surface, the device further comprising:

a photosensing component with a photosensitive surface;

the exit surface being on or over the photosensitive surface.

24. A system comprising the device of claim 11, the system further comprising:

control circuitry connected to the signal-responsive component, the control circuitry providing the tuning signals.

25. The system of claim 24 in which the tuning structure further includes:

one or more sensing components that can provide shape sense signals indicating shape of one or more of the deformable components;

the control circuitry receiving the shape sense signals and providing the tuning signals based on the shape sense signals.

26. The system of claim 24 in which the signal-responsive components include:

first and second electrodes connected to opposite surfaces of the deformable component;

the control circuitry measuring capacitance between the first and second electrodes to sense the deformable component'"'"'s shape.

27. A method of operating the system of claim 24, the method comprising:

operating the control circuitry to provide a series of tuning signals so that the tuning structure moves the first and second reflective components continuously across a range of relative positions within the set of relative positions.

28. A method of producing an optical cavity device, the method comprising:

producing an optical cavity device that includes;

first and second light-reflective components with a light-transmissive region between them, each of the light-reflective components being able to reflect light into the light-transmissive region; and

a tuning structure that, in response to tuning signals, can move the first and second light-reflective components to any of a set of positions relative to each other;

the tuning structure including;

one or more deformable components connected so that deformation of at least one of the deformable components causes the first and second light-reflective components to move within the set of positions; and

at least one signal-responsive component that receives the tuning signals and, in response, causes deformation of at least one of the deformable component;

the act of producing the optical cavity device comprising;

producing the optical cavity device with an analyte region within the light-transmissive region, the analyte region being capable of having an analyte in it, the set of positions including a subset of one or more positions in which the first and second light-reflective components and the light-transmissive region with analyte in the analyte region can operate as an optical cavity that provides analyte-affected output light, the analyte-affected output light including information about one or more optical characteristics of the analyte.

29. The method of claim 28 in which the act of producing the optical cavity device further comprises:

depositing and patterning a layer of elastomer to produce the deformable components.

30. The method of claim 29 in which the act of producing the optical cavity device further comprises:

before the act of depositing and patterning the layer of elastomer, producing an underlying structure that includes the first light-reflective component on a photosensitive surface of a photosensing component; and

after the act of depositing and patterning the layer of elastomer, attaching an overlying structure over the deformable components, the overlying structure including the second light-reflective component.

31. The method of claim 30 in which the signal-responsive component includes first and second electrodes on opposite sides of one of the deformable components, the act of producing the optical cavity device further comprising:

producing the first electrode on an upper surface of the underlying structure before the act of depositing and patterning the layer of elastomer material; and

producing the second electrode on upper surfaces of the deformable components before the act of attaching the overlying structure.

32. The method of claim 28 in which the act of producing the optical cavity device further comprises:

providing a sequence of tuning signals to the signal-responsive component to cause one or more of the deformable components to be deformed into a sequence of shapes; and

during the sequence of tuning signals, when output light from the optical cavity meets a criterion, fixing the deformable component'"'"'s shape.