In the method of and apparatus for measuring a spectral absorption in an opaque specimen, a scattering specimen is illuminated with highly directional light of variable wavelength from a specific direction, thereby removing scattered rays as much as possible, and thus detecting the intensity of only...http://www.google.de/patents/US5345306?utm_source=gb-gplus-sharePatent US5345306 - Method and apparatus for measuring spectral absorption in an opaque specimen and method and apparatus for measuring the microscopic absorption distribution
