Inverse method
The concept behind the inverse method described in this chapter
is straightforward (Figure 6.1): (a) guess a set of optical
properties; (b) calculate the reflection and transmission; (c)
compare the calculated values with the measured reflection and
transmission; (d) if the calculated and measured values are not
equal then repeat the process with a new guess.
Three measurements are required to determine three unknowns.
Two possible sets of measurements are the diffuse reflection
Rdiffusemeas, the total transmission
Ttotalmeas, and the collimated transmission
Tcollmathrmmeas, or
alternatively,
Rdiffusemeas,
Ttotalmeas, and the anisotropy of the phase function
gHG.
The first set requires removal of the integrating sphere assembly
in the spectrophotometer and the second set requires an independent
measurement of the anisotropy of the tissue with a goniophotometer.
In Section 6.1.1 below the uniqueness of the optical properties
obtained from such measurements is discussed. Section 6.1.2
contains details of the inversion process.
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