Analysis by photo acoustic displacement and interferometryl

• US 20110125004A1
• Filed: 07/24/2009
• Published: 05/26/2011
• Est. Priority Date: 07/31/2008
• Status: Abandoned Application

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Von Basum, Golo, Moeskops, Bastiaan Wilhelmus Maria, Liu, Yan, Thumma, Kiran Kumar
• Application Number:
  US13/055,531
• Publication Number:
  US 20110125004A1
• Time in Patent Office: Days
• US Class Current: 600/407
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/0064 Body surface scanning
• CPC Class Codes: A61B 5/0095 by applying light and detecting acoustic waves, i.e. photoacoustic measurements
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/1455 using optical sensors, e.g. spectral photometrical oximeters

Abstract

A device for analyzing a material, the device having a photo acoustic generator (40) for generating pressure waves in the material by pulsed illumination by a light source, and a sensor (20, 30, 50) for producing a signal using self mixing interferometry, the signal representing displacements of the material due to the pressure waves, and a signal processor (60) for processing the signal to analyze the material. This combination of photo acoustic stimulation and self mixing interferometry sensing helps reduce or avoid errors or distortions caused by sensor contact on the material, and can provide a better ratio of sensitivity for a given degree of compactness of the device.

Claims

1. A device for analyzing a material, the device having a photo acoustic generator (40) for generating pressure waves in the material by pulsed illumination by a light source, and a sensor (30, 50) for producing a signal using self mixing interferometry, of displacements of the material due to the pressure waves, and a signal processor (60) for processing the signal to analyze the material.

2. The device of claim 1, the sensor comprising a laser diode (30) for outputting light which is directed towards the material so that a proportion is reflected so as to mix in a cavity (20) of the laser diode to form a modulation, the sensor also having an analyzer (50) for generating a signal representing the displacements by analyzing the modulation.

3. The device of claim 1 having an opto mechanical arrangement for scanning the sensor over an area of the material.

4. The device of claim 1, having an array of sensors for simultaneously generating signals for an area of the material.

5. The device of claim 1 having a near infra red spectroscope sensor for generating a further measurement of the material.

6. The device of claim 1, the sensor being arranged to sense parts of the material below a surface of the material.

7. The device of claim 1, the sensor being arranged to sense parts of the material on a surface of the material.

8. The device of claim 1, arranged as a non invasive monitor for monitoring concentration of constituents of blood in a human or animal body.

9. A method of analyzing a material, having the steps of photo acoustically generating pressure waves in the material by pulsed illumination by a light source, producing a signal using self mixing interferometry, of displacements of the material due to the pressure waves, and processing the signal to analyze the material.

10. The method of claim 9, having the step of generating an image of the material.

11. The method of claim 9 for non invasive monitoring of blood in a human or animal body, having the step of processing the signal to determine the concentration of given constituents of the blood.

12. The method of claim 9 having the steps of processing the signal to provide alignment information, and aligning the device on the material on the basis of the information before processing the signal to analyze the material.

13. A controller for controlling a device for analyzing a material, the controller having means for controlling photo acoustic generation of pressure waves in the material by pulsed illumination by a light source, and means for processing a signal to analyze the material, the signal being of displacements of the material due to the pressure waves obtained from self mixing interferometry.

14. The controller of claim 13 for use with a device for non invasive monitoring of blood in a human or animal body, the means for processing the signal outputting a value related the concentration of given constituents of the blood.

15. The controller, claim 13 having means for processing the signal to provide alignment information before processing the signal to analyze the material.