Determining a flow characteristic of an object being movable in an element

• US 9,091,573 B2
• Filed: 05/22/2012
• Issued: 07/28/2015
• Est. Priority Date: 06/01/2011
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Van Der Lee, Alexander Marc, Veen, Jeroen
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): Rahman, Md
• Application Number:
  US14/117,635
• Publication Number:
  US 20140085635A1
• Time in Patent Office: 1,162 Days
• Field of Search: 356/342
• US Class Current: 1/1
• CPC Class Codes: A61B 2562/0233 Special features of optical sensors or probes classified in A61B5/00
• CPC Class Codes: A61B 2562/146 for optical coupling
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/6801 specially adapted to be attached to or worn on the body surface
• CPC Class Codes: G01F 1/00 Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow measuring a proportion of the volume flow G01F5/00
• CPC Class Codes: G01N 21/53 within a flowing fluid, e.g. smoke
• CPC Class Codes: G01P 3/366 by using diffraction of light for measuring speed of fluids G01P5/26
• CPC Class Codes: G01P 5/26 by measuring the direct influence of the streaming fluid on the properties of a detecting optical wave
• CPC Class Codes: G01S 17/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 17/88 Lidar systems specially adapted for specific applications
• CPC Class Codes: G01S 7/4916 using self-mixing in the laser cavity
• CPC Class Codes: G01S 7/4917 superposing optical signals in a photodetector, e.g. optical heterodyne detection

Abstract

A sensor device (340) for determining a flow characteristic of an object (341) being movable in an element (342) comprises a light emitting unit (344) configured for emitting light towards the element (342) and a light detecting unit (344) configured for detecting light scattered back from the element (342). The sensor device (340) comprises an optical unit (346) configured for spatially separating a light incidence element portion (348) of the element (342) and a light detection element portion (350) of the element (342) from one another, wherein the light incidence element portion (348) is associated with the emitted light inciding on the element (342) and the light detection element portion (350) is associated with the back-scattered light scattered back from the element (342) for detection. The sensor device (340) comprises a determining unit (358) configured for determining the flow characteristic of the object (341) being movable in the element (342) based on light indicative of the emitted light and the detected back-scattered light. The sensor device (340) allows for an accurate and easy determination of the flow characteristic of the object (341).

Claims

1. A sensor device for determining a flow characteristic of an object being movable in an element, the sensor device comprising:

a light emitting unit configured for emitting light towards the element,

a light detecting unit configured for detecting light scattered back from the element,

an optical structure including a light incidence lens portion and a light detection lens portion, the light incidence lens portion and the light detection lens portion being displaced from one another, wherein the light incidence lens portion is configured to emit light incident on the a first portion of the element and the light detection lens portion is configured to receive back-scattered light which is scattered back from a second portion of the element for detection, the first and second element portions being separated from each other, wherein the optical structure blocks any back-scattered light received by the light incident lens portion, and

a unit configured for receiving light indicative of the emitted light and the detected back-scattered light such that the flow charactistics of the moveable object are determinable by self-mixing interferometry.

2. The sensor device according to claim 1, wherein the light emitting unit and the light detecting unit are integrally formed.

3. The sensor device according to claim 1, wherein the optical unit comprises a light path separation element configured for separating a light path of the emitted light towards the light incidence element portion from a light path of the back-scattered light scattered back from the light detection element portion.

4. The sensor device according to claim 3, wherein the light path separation element is configured as a polarizing beam splitter, wherein a polarization direction of the emitted light emitted by the light emitting unit is oriented under an angle of 45 degrees with respect to a polarization axis of the polarizing beam splitter.

5. The sensor device according to claim 3, wherein the optical unit comprises a light redirecting element configured for redirecting the emitted light received from the light path separation element towards the light incidence element portion.

6. The sensor device according to claim 5, wherein a distance between the light incidence element portion and the light detection element portion is adjustable by a relative arrangement of the light path separation element and the light redirecting element.

7. The sensor device according to claim 1, the sensor device further comprising:

a polarization alternation element arranged between the optical unit and the element, wherein the polarization alternation element is configured for altering a polarization of the emitted light received from the optical unit and a polarization of the back-scattered light scattered back from the element.

8. The sensor device according to claim 7, wherein the optical unit and the polarization alternation element are configured and are arranged relative to one another such that a polarization of the back-scattered light detected by the light detecting unit and a polarization of the light indicative of the emitted light are orthogonal to one another.

9. The sensor device according to claim 1, the sensor device further comprising:

a first lens arranged between the optical unit and the light incidence element portion, wherein the first lens is configured for focusing the emitted light towards the light incidence element portion, and/or

a second lens arranged between the optical unit and the light detection element portion, wherein the second lens is configured for focusing the back-scattered light scattered back from the light detection element portion.

10. The sensor device according to claim 1, the sensor device further comprising:

a first optical fiber arranged between the optical unit and the light incidence element portion, wherein the first optical fiber is configured for directing the emitted light from the optical unit towards the light incidence element portion, and/or

a second optical fiber arranged between the optical unit and the light detection element portion, wherein the second optical fiber is configured for directing the back-scattered light from the light detection element portion to the optical unit.

11. The sensor device according to claim 1, the sensor device further comprising:

a third lens arranged between the light detecting unit and the optical unit, wherein the third lens is configured for focusing the back-scattered light towards the light detecting unit.

12. The sensor device according to claim 1, wherein the flow characteristic of the object comprises at least one of a flow velocity of the object and a flow direction of the object, and/or wherein the object comprises a blood cell and the element comprises a skin.

13. A method of determining a flow characteristic of an object being movable in an element, the method comprising:

emitting light towards the element by a light source,

detecting light scattered back from the element by a light detector, and

receiving light indicative of the emitted light and the detected back-scattered light with a unit to enable the flow characteristics of the moveable object to be determined by self-mixing interferometry,

wherein a light incidence element portion of the element and a light detection element portion of the element are spatially separated from one another by an optical structure, wherein the optical structure channels emitted light from the light source to the light incidence element portion, channels backscattered light from the light detection element portion to the receiving unit, and prevents back-scattered light from the incident element portion from reaching the determining unit.

14. The method of claim 13, further comprising:

separating a light path of the emitted light towards the light incidence element portion from a light path of the back-scattered light scattered back from the light detection element portion with a light path separation element.

15. The method of claim 14, further comprising:

redirecting the emitted light received from the light path separation element towards the light incidence element portion with a light redirecting element; and

adjusting a distance between the light incidence element portion and the light detection element portion by a relative arrangement of the light path separation element and the light redirecting element.

16. The method of claim 13, further comprising:

altering a polarization of the emitted light received from the optical device and a polarization of the back-scattered light scattered back from the element with a polarization alternation element.

17. A sensor device for determining a flow characteristic of blood flowing in skin, the sensor device comprising:

a light source;

an optical element including;

a light path separation element,

a first optical element portion extending from adjacent the light source to the light path separation element,

a second optical element portion extending from the light path separation element to a light output end adjacent an incident light region of the skin to receive incident light from the light source,

a third optical element portion extending from a light receiving end adjacent another region of the skin displaced from the incident light region of the skin to receive backscattered light from the another region of the skin to convey the reeived backscattered light to the light path separation element;

wherein the light separation element is configured to;

pass light from the first optical element portion to the second optical element portion and block light from passing from the first optical element portion to the third optical element portion, and

pass the backscattered light from the third optical element portion to the first optical element portion; and

a means for determining a flow characteristic of the blood from backscattered light received from the third optical element portion and the light from the light source.

18. The sensor device according to claim 17, wherein the light path separation element includes a polarizing beam splitter.

19. The sensor device according to claim 18, further including:

a polarizing plate disposed adjacent the outlet end of the second optical element portion, the polarizing plate and the polarizing beam splitter being polarized such that backscattered light from the incident light region of the skin is blocked from passing into the first optical element portion.

20. The sensor device according to claim 19, wherein the flow determining means includes an interferometer.