OPTICAL DEVICE FOR ASSESSING OPTICAL DEPTH IN A SAMPLE

• US 20100113941A1
• Filed: 02/18/2008
• Published: 05/06/2010
• Est. Priority Date: 02/20/2007
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Van Gogh, Antonius T.M., Zou, Hans, Hendriks, Bernardus H.W.
• Granted Patent: US 8,175,690 B2
• Time in Patent Office: Days
• US Class Current: 600/478
• CPC Class Codes: A61B 2562/0242 for varying or adjusting the optical path length in the tissue
• CPC Class Codes: A61B 5/0075 by spectroscopy, i.e. measuring spectra, e.g. Raman spectroscopy, infrared absorption spectroscopy A61B5/0071 takes precedence
• CPC Class Codes: A61B 5/0084 for introduction into the body, e.g. by catheters A61B5/1459 takes precedence
• CPC Class Codes: A61B 5/444 Evaluating skin marks, e.g. mole, nevi, tumour, scar
• CPC Class Codes: G01N 2021/4792 Polarisation of scatter light
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B

Abstract

The present invention relates to an optical device for assessing optical depth (D) in a sample (100) illuminated by polarized radiation (20) from a source (10). A first and a second radiation guide have their end portions (3Oa′, 30b′) arranged for capturing reflected radiation (25a, 25b) from the sample. A detector (40) measures a first polarization (P1) and a second polarization (P_—2) of the reflected radiation (25), and a first and a second intensity (II, 12) of the reflected radiation (25a, 25b) in the first (30a) and the second (30b) radiation guide, respectively. Processing means (60) then calculates a first (f) and a second (g) spectral function, both spectral functions (f, g) being indicative of single scattering events in the sample. The processing means (60) is further arranged to calculate a measure of the correlation (C) between the first (f) and a second (g) spectral function so as to assess whether the single scattering events originate from substantially the same optical depth (D) within the sample. Thus, the causal relation between the first and second spectral functions can be used for assessing whether the single scattering events giving rise to the two spectral functions come from substantially the same optical depth (D) within the sample. The invention is particular advantageous for optically probing an epithelial layer of a patient.

Claims

1. An optical device for assessing optical depth (D) in an associated sample (100), the device comprising:

a radiation source (10) capable of emitting radiation (20) with an initial polarization (P_0),

a first (30a) and a second (30b) radiation guide, the first radiation guide (30a) being optically connected to the radiation source for emitting radiation (20) to the sample,

the first and the second radiation guide having their respective end portions (30a′

, 30b′

) substantially aligned with each other, the end portions further being arranged for capturing reflected radiation (25a, 25b) from the sample,

a detector (40) being optically connected to the first and the second radiation guide, the detector being arranged for measuring, within an optical subband, an indication of;

a first polarization (P_1) of the reflected radiation (25),

a second polarization (P_2) of the reflected radiation (25), said second polarization (P_2) being different from the first polarization (P_1), and

a first and a second intensity (I_1, I_2) of the reflected radiation (25a, 25b) in the first (30a) and the second (30b) radiation guide, respectively, and

processing means (60) operably connected to the detector, the processing means being adapted to calculate a first (f) and a second (g) spectral function within the optical subband, both spectral functions (f, g) being substantially indicative of single scattering events in the sample;

the first spectral function (f) being a measure of the difference in polarization between the first (P_1) polarization of the reflected radiation (25) and the second (P_2) polarization of the reflected radiation (25), and

the second spectral function (g) being a measure of the difference in intensity between the first and second intensities (I_1, I_2) of the reflected radiation,

wherein the processing means (60) is further arranged to calculate a measure of the correlation (C) between the first (f) and a second (g) spectral function so as to assess whether the single scattering events originate from substantially the same optical depth (D) within the sample.

2. An optical device according to claim 1, wherein the first spectral function (f) is a polarized light scattering spectroscopy (PLSS) function.

3. An optical device according to claim 1, wherein the second spectral function (g) is a measure of the differential path length (DPL) between the first (30a) and the second (30b) radiation guide.

4. An optical device according to claim 1, wherein the detector is arranged for measuring, within the optical subband, the first polarization (P_1) and the second polarization (P_2) of the reflected radiation (25) captured by the first radiation guide (30a).

5. An optical device according to claim 1, wherein a third radiation guide (30c) is arranged for transmitting radiation (20) with the initial polarization (P_0) to the sample, the third radiation guide having an end portion (30c′

) substantially aligned with the end portions (30a′

, 30b′

) of the first and the second radiation guide.

6. An optical device according to claim 5, wherein the third radiation guide (30c) is arranged for capturing reflected radiation (25c) from the sample, the third radiation guide (30c) being optically connected to the detector.

7. An optical device according to claim 1, wherein the detector is arranged for measuring the first (P_1) and the second (P_2) polarization of the reflected radiation (25a, 25b, 25c) in two substantially orthogonal directions.

8. An optical device according to claim 1, wherein the radiation source (10) is arranged for emitting radiation having the initial polarization (P_0) linearly polarized in a plane substantially parallel to a polarization plane of the measured first (P_1) or the measured second (P_2) polarization.

9. An optical device according to claim 1, wherein the first, the second and/or the third radiation guide are optical fibres having a diameter of maximum 200 micrometer, preferably maximum 100 micrometer, or even more preferably maximum 50 micrometer

10. An optical device according to claim 1, wherein the processing means are further arranged for determining the correlation (C) for more than one region within the optical subband, the processing means being adapted to subsequently select a region of optimum correlation (C) for subsequent optical measurements.

11. An optical device according to claim 1, wherein the processing means are further arranged for changing the optical subband in dependency on the found correlation (C).

12. An optical device according to claim 1, wherein the optical device comprises actuation means arranged for changing at least the distance (d) of the respective end portions (30a′

, 30b′

) between the first and second radiation guide in dependency of the correlation (C).

13. An optical device according to claim 1, wherein the first, the second and/or the third radiation guide forms part of a catheter.

14. A catheter arranged for cooperation with an associated optical device, the catheter comprising:

a first (30a) and a second (30b) radiation guide, the first radiation guide (30a) being optically connectable to an radiation source for emitting radiation (20) to a sample (100),

the first and the second radiation guide having their respective end portions (30a′

, 30b′

) substantially aligned with each other, the end portions further being arranged for capturing reflected radiation (25a, 25b) from the sample,

the associated optical device comprising;

a radiation source (10) capable of emitting radiation (20) with an initial polarization (P_0),

a detector (40) being optically connected to the first and the second radiation guide, the detector being arranged for measuring, within an optical subband, an indication of;

a first polarization (P_1) of the reflected radiation (25),

a second polarization (P_2) of the reflected radiation (25), said second polarization (P_2) being different from the first polarization (P_1), and

a first and a second intensity (I_1, I_2) of the reflected radiation (25a, 25b) in the first (30a) and the second (30b) radiation guide, respectively, and

processing means (60) operably connected to the detector, the processing means being adapted to calculate a first (f) and a second (g) spectral function within the optical subband, both spectral functions (f, g) being substantially indicative of single scattering events in the sample;

the first spectral function (f) being a measure of the difference in polarization between the first (P_1) polarization of the reflected radiation (25) and the second (P_2) polarization of the reflected radiation (25), and

the second spectral function (g) being a measure of the difference in intensity between the first and second intensities (I_1, I_2) of the reflected radiation,

the processing means (60) further being arranged to calculate a measure of the correlation (C) between the first (f) and a second (g) spectral function so as to assess whether the single scattering events originate from substantially the same optical depth (D) within the sample.

15. A catheter according to claim 14, wherein a third radiation guide (30c) is arranged for transmitting radiation (20) with the initial polarization (P_0) to the sample, the third radiation guide having an end portion (30c′

) substantially aligned with the end portions (30a′

, 30b′

) of the first and the second radiation guide.

16. A catheter according to claim 15, wherein the third radiation guide (30c) is arranged for capturing reflected radiation (25c) from the sample, the third radiation guide (30c) being optically connectable to the detector.

17. A catheter according to claim 14, wherein the first (25a), the second (25b) and/or the third (25c) radiation guide have polarization conserving properties.

18. A method for operating an optical device for assessing optical depth (D) in a sample (100), the method comprising:

emitting radiation (20) with an initial polarization (P_0) with a radiation source (10),

arranging a first (30a) and a second (30b) radiation guide in relation to the sample, the first radiation guide (30a) being optically connected to the radiation source for emitting radiation (20) to the sample, the first and the second radiation guide having their respective end portions (30a′

, 30b′

) substantially aligned with each other, the end portions further being arranged for capturing reflected radiation (25a, 25b) from the sample,

providing a detector (40) in optical connection to the first and the second radiation guide, the detector being arranged for measuring, within an optical subband, an indication of;

a first polarization (P_1) of the reflected radiation (25),

a second polarization (P_2) of the reflected radiation (25), said second polarization (P_2) being different from the first polarization (P_1), and

a first and a second intensity (I_1, I_2) of the reflected radiation (25a, 25b) in the first (30a) and the second (30b) radiation guide, respectively, and

providing processing means (60) operably connected to the detector, the processing means being adapted to calculate a first (f) and a second (g) spectral function within the optical subband, both spectral functions (f, g) being substantially indicative of single scattering events in the sample;

the first spectral function (f) being a measure of the difference in polarization between the first (P_1) polarization of the reflected radiation (25) and the second (P_2) polarization of the reflected radiation (25), and

the second spectral function (g) being a measure of the difference in intensity between the first and second intensities (I_1, I_2) of the reflected radiation,

calculating by the processing means (60) a measure of the correlation (C) between the first (f) and a second (g) spectral function so as to assess whether the single scattering events originate from substantially the same optical depth (D) within the sample.

19. A computer program product being adapted to enable a computer system comprising at least one computer having data storage means associated therewith to control an optical device according to claim 18.