Apparatus and method for direct measurement of absorption and scattering coefficients in situ

A method for measuring an absorption coefficient, comprising:

• introducing light into a cavity between a first diffusive material and a second diffusive material, wherein at least some of the light in the cavity passes into the first and second diffusive material and at least some of the light passing into the second diffusive material passes through a transparent material proximate to the second diffusive material and into an absorptive material;
• measuring a first intensity comprising the intensity of the light in the first diffusive material;
• measuring a second intensity comprising the intensity of the light in the second diffusive material;
• and
• determining an absorption coefficient for the absorptive material based on the first and second intensity measurements.

An apparatus, comprising:

• a first diffusive material;
• a second diffusive material inside the first diffusive material separated from the first diffusive material by a cavity;
• a transparent material proximate to an inner surface of the second diffusive material operable to hold an absorptive material;
• first light detectors operable to measure a first light intensity in the first diffusive material;
• and
• second light detectors operable to measure a second light intensity in the second diffusive material, wherein an absorption coefficient for the absorptive material in the transparent material may be determined based on the first and second light intensities measured when the cavity is illuminated by a light source.

A method for measuring a scattering coefficient, comprising:

• illuminating an absorptive material with a collimated beam having an incident light intensity, wherein the absorptive material is within a transparent material substantially surrounded by a diffusive material;
• measuring a diffused light intensity in the diffusive material;
• and
• determining a scattering coefficient for the absorptive material based on diffused light intensity and the incident light intensity.

An apparatus, comprising:

• a transparent material operable to hold an absorptive material;
• a diffusive material substantially surrounding the transparent material;
• light detectors operable to detect a diffused light intensity in the diffusive material;
• a light source operable to illuminate an absorptive material with a collimated beam having an incident light intensity, wherein a scattering coefficient for the absorptive material may be determined based on the incident light intensity and the diffused light intensity.