Abstract: Methods and apparatus are provided for determining a characteristic of a sample of a material by the interaction of electromagnetic radiation with the sample. The apparatus includes a source of electromagnetic radiation, an optical assembly and a detector. The optical assembly sequentially illuminates a plurality of volume elements in the sample with an intensity distribution in the sample that drops off substantially monotonically from a first region in a first optical path and collects electromagnetic radiation emanating from each of the volume elements. The optical assembly collects the electromagnetic radiation emanating from each of the volume elements with a collected distribution that drops off substantially monotonically from a second region in a second optical path. The first and second regions at least partially overlap in each of the volume elements.

Abstract: An optical probe collects light emanating from a specimen that selectively andpreferentially represents a localized volume element within the sample, with illuminationintensity and collection efficacy both dropping off away from the localized volume element to limit the integrated contribution from outside the element. For example, the optics provide high peak illumination and high collection efficiency which both overlap in volume elements of a limited size corresponding to a structure or process of the specimen. The resulting collected signal comprising one or more spectral segments is highly correlated with optical characteristics, such as absorbance, scattering or fluorescence characteristics of material in the small volume elements. A processor may apply a previously-derived vector or matrix transform to the collected responses to produce an output.

Abstract: An optical probe collects light responses from a specimen that selectively and preferentially emanates from a localized volume element within the sample, with illumination irradiance and collection efficiency both dropping off away from the localized volume element, and a processor applies a vector or matrix transform to collected responses to produce an output. The optics provide high peak illumination and high collection efficiency which both overlap in small volume elements that are limited in length, width or depth to correspond to a structure or process of the specimen so that the collected spectra or other responses have high signal strength and enhanced correlation values to small or otherwise inaccessible or masked effects present in macroscopic or submacroscopic regions.