In the investigations of inhomogeneous media, availability of methods to study the interior of the material without affecting it is valuable. Optical coherence tomography provides such a functionality, by providing depth resolved images of semi-transparent objects non-invasively. This is especially useful in medicine, and is used not only in research, but also in clinical practice. Optical coherence tomography characterizes each cross-section by its reflectance. It is clearly desirable to obtain more detailed information regarding each cross-section, if available. We have developed a system which measures the fluctuation spectrum of all the cross-sections in optical coherence tomography. By providing more information for each cross-section, this can in principle be effective in tissue characterization and pathological diagnosis. The system uses the time dependence of the optical coherence tomography data, to obtain the fluctuation spectrum of each cross-section. Additionally, noise reduction is applied to obtain the spectra without unwanted noise, such as shot-noise, which can swamp the signal. The measurement system is applied to samples with no external stimuli, and depth resolved thermal fluctuation spectra of the samples are obtained. These spectra are compared with their corresponding theoretical expectations, and are found to agree. The measurement system requires dualizing the detectors in the optical coherence tomography, but otherwise requires little additional equipment. The measurements were performed in ten to a hundred seconds.
|Publication status||Published - 2017 Dec 24|
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