Patent ID: 8730466

Claim:
An optical device comprising: a converging lens device mounted to receive light from at least one light source that comprises: a first light source configured to emit first light approximately centered at a first wavelength, wherein the first wavelength is selected for analysis of the sample; a second light source configured to emit second light approximately centered at a second wavelength, wherein the second wavelength is selected for analysis of the sample, and further wherein the second wavelength is different from the first wavelength and from the baseline wavelength; a baseline light source configured to emit baseline light approximately centered at a baseline wavelength, wherein the baseline wavelength is different from the first wavelength and is selected to be centered in a region of the electromagnetic spectrum that is not used for analysis of the sample, wherein the received light is substantially collimated, and further wherein the converging lens device is configured to focus the received light onto a transmitting optical fiber; the transmitting optical fiber comprising an entrance face and an exit face, wherein the transmitting optical fiber is mounted to receive the focused light through the entrance face and to transmit the received, focused light from the exit face, through a sample and onto a receiving optical fiber; a beamsplitter; a reference detector, wherein the beamsplitter is mounted between the first light source and the converging lens device and is configured to reflect a baseline portion of the baseline light, a first portion of the first light, and a second portion of the second light towards the reference detector, wherein the reference detector is configured to generate a first reference signal indicating a first intensity of the first portion of the first light, a second reference signal indicating a second intensity of the second portion of the second light, and a third reference signal indicating a third intensity of the baseline portion of the baseline light; a sample holder configured to hold the sample for analysis; and the receiving optical fiber comprising an entrance face and an exit face, wherein the receiving optical fiber is mounted to receive the transmitted light through the entrance face of the receiving optical fiber after transmission through the sample, wherein the converging lens device is positioned to focus the received light onto the entrance face of the transmitting optical fiber such that a half-angle of the angular distribution of the focused light that reaches the entrance face of the transmitting optical fiber is selected to underfill an entrance aperture of the entrance face of the receiving optical fiber in both a spatial dimension and an angular dimension.