Method and apparatus for determination of optical properties of light scattering material

• US 5,867,807 A
• Filed: 10/25/1996
• Issued: 02/02/1999
• Est. Priority Date: 10/26/1995
• Status: Expired due to Term

• Current Assignee: Hamamatsu Photonics KK, Kabushiki Kaisha Square Enix
• Original Assignee: Hamamatsu Photonics KK, Kabushiki Kaisha Square Enix
• Inventors: Araki, Ryuichiro, Yamada, Yukio, Yamashita, Yutaka
• Primary Examiner(s): Trammell, James P.
• Assistant Examiner(s): KEMPER, MELANIE A
• Application Number:
  US08/738,110
• Time in Patent Office: 830 Days
• Field of Search: 364/525, 600/310, 600/300, 356/442, 356/301, 356/433, 702/30, 702/22, 702/23, 250/306, 250/307, 250/341.1
• US Class Current: 702/30
• CPC Class Codes: G01N 21/49 within a body or fluid

Abstract

A method for determination of optical properties of light scattering material, includes calculating temporal changes in output light intensity with respect to a large number of combinations of reduced scattering coefficients μs'"'"' and absorption coefficients μa of a light-scattering material sample, storing the results, irradiating the sample with picosecond pulses of light and measuring temporal changes in the intensity of light coming out from the sample. When a measured temporal change in output light intensity is the same as or similar to a stored temporal change in intensity, the reduced scattering coefficient μs'"'"' and absorption coefficient μa of the stored temporal change in output light intensity are determined as the μs'"'"' and μa of the sample.

Claims

1. A method for determination of optical properties of light scattering material, comprising:

a step of numerically calculating and storing beforehand time response characteristics at a prescribed point on a scattering material sample in respect of numerous combinations of reduced scattering coefficients and absorption coefficients;

a step of irradiating light pulses at the sample and measuring time response characteristics of output light at a prescribed point;

a step in which agreement or similarity between a measured time response characteristic and any stored time response characteristic is analyzed by comparing the characteristics including calculating a log of a ratio of measured time response characteristics of output light to calculated time response characteristics for each time, and selecting a calculated time response characteristic at which the calculation outcome is linear or can be regarded as linear relative to time; and

a step in which a reduced scattering coefficient and absorption coefficient of the sample are determined from an outcome of the analysis.

2. The method according to claim 1, wherein the numerical calculation is by a Monte Carlo method.

3. The method according to claim 1, wherein the numerical calculation is by a numerical analysis method.

4. The method according to claim 1, wherein wavelength of the light pulses is from a wavelength of visible light to 2 μ

m.

5. A method for determination of optical properties of light scattering material, comprising:

a step of numerically calculating and storing beforehand time response characteristics at a prescribed point on a scattering material sample in respect of numerous equivalent scattering coefficients and an absorption coefficient of zero;

a step of irradiating light pulses at the sample and measuring time response characteristics of output light at a prescribed point;

a step of calculating a log of a ratio of measured time response characteristics to stored time response characteristics for each time, and selecting a time response characteristic at which the calculation outcome is linear or can be regarded as linear relative to time; and

a step in which a stored equivalent scattering coefficient that provides the time response characteristic at which the calculation outcome is linear or can be regarded as linear is determined as a reduced scattering coefficient of the sample, and an absorption coefficient of the sample is determined from a slope of temporal change in the calculation outcome that is linear or can be regarded as linear.

6. The method according to claim 5, wherein the numerical calculation is by a Monte Carlo method.

7. The method according to claim 5, wherein the numerical calculation is by a numerical analysis method.

8. The method according to claim 5, wherein wavelength of the light pulses is from a wavelength of visible light to 2 μ

m.

9. An apparatus for determining optical properties of light scattering material, comprising:

means for numerically calculating and storing beforehand time response characteristics at a prescribed point on a scattering material sample in respect of numerous combinations of reduced scattering coefficients and absorption coefficients;

means of irradiating light pulses at the sample and measuring time response characteristics of output light at a prescribed point;

means of analyzing agreement or similarity between a measured time response characteristic and any stored time response characteristic by comparing the characteristics including means of calculating a log of a ratio of measured time response characteristics to stored time response characteristics for each time and selecting a time response characteristic at which the calculation outcome is linear or can be regarded as linear relative to time; and

means of determining a reduce scattering coefficient and absorption coefficient of the sample from an outcome of the analysis.

10. The method according to claim 9, wherein the numerical calculation is by a Monte Carlo method.

11. The method according to claim 9, wherein the numerical calculation is by a numerical analysis method.

12. An apparatus for determining optical properties of light scattering material, comprising:

means for numerically calculating and storing beforehand time response characteristics at a prescribed point on a scattering material sample in respect of numerous reduced scattering coefficients and an absorption coefficient of zero;

means of irradiating light pulses at the sample and measuring time response characteristics of output light at a prescribed point;

means of calculating a log of a ratio of measured time response characteristics of output light to calculated time response characteristics for each time and selecting a stored time response characteristic at which the calculation outcome is linear or can be regarded as linear relative to time;

means that determines a stored reduced scattering coefficient that provides the time response characteristic at which the calculation outcome is linear or can be regarded as linear, as a reduced scattering coefficient of the sample, and determines an absorption coefficient of the sample from a slope of temporal change in the calculation outcome that is linear or can be regarded as linear.

13. The method according to claim 12, wherein the numerical calculation is by a Monte Carlo method.

14. The method according to claim 12, wherein the numerical calculation is by a numerical analysis method.