| Cancer has been one of the most serious threats to human life. However, there is no substantial improvement in overall treatment of cancer patients. One of the key reasons is the unavailability of convenient method to detect cellular alterations in ultra-early stage of carcinogenesis processes, where genetic aberrations at nano-scale have not yet resulted in histological changes. The process of carcinoma formation involves stepwise accumulation of genetic and epigenetic alterations in epithelial cells over a time period of many years. Dysplasia, or structural alterations detectable by microscopy, is a relatively late event in this process. From a cancer-research perspective, it is important to recognize the earlier stages of carcinogenesis that precede histological changes.In this paper, we described an optical method based on reflective mesoscopic spectroscopy. for nano-scale refractive index alternations detection. The proposed method might be useful in probing statistical structural changes at nano-scale which are unperceivable up to now, and hence avoiding the limitation due to optical diffraction in far field.According to analysis of the model of biological cell, the conditions and methods to make sure the one-dimensional optical transmission in cell were confirmed. These provided the basis to the design of Reflective Mesoscopic Spectroscopy acquisition and processing system, and also provided guidance to the high signal to noise detection of reflective spectrum and the correct separation of spectral fluctuation components. According to mesoscopic light transport theory, the mechanism of mesoscopic spectroscopy for perceiving reflective index fluctuations at length scale of nanometers is revealed, and the feasibility of taking disorder strength as the optical fingerprint of a cancerous cell is analyzed.Based on simulation by finite difference time domain method, light propagation in one-dimensional refractive-index variable medium and resulting reflective spectral characteristics are analyzed. Through precise control of the standard deviation and spatial correlation length of the refractive index fluctuations along the one-dimensional channel, simulated disorder strengths and their relation to theoretical settings are quantitatively analyzed. The results show that reflective spectrum are highly sensitive to disorder strength and thus it is feasible for the refractive index fluctuations at nano-scale within the one-dimensional channel to be perceived through reflective spectrum. Under certain approximating conditions, disorder strength is proportionally enlarged with increasing variance and spatial correlation length describing the refractive index fluctuations.Based on the above theory, Reflective Mesoscopic Spectroscopy acquisition and processing system was established. Building the lighting unit and imaging unit, making a trade-off between the mesoscopic channel's lateral scale, diffraction limited lateral scale, the degree of beam collimation and spatial coherence. According to the optimization of design of experiment system, ensure the implementation of quasi-one-dimensional optical transmission and spatially incoherent inhibition, to achieve the far-field detection of reflective meoscopic spectrum. A series experiments of glass slide and film coating slide were carried out, the experimental results showed that the imaging technique of reflective mesoscopic spectroscopy can effectively distinguish the difference of disorder strength on sample which is impossible for traditional microscopic techniques.This thesis made some exploratory research on the detection of ultra-early stage of tumor cell which is vary urgent and challenging in nowadays. In order to develop a totally new imaging modality which can be used to diagnosis the ultra-early stage of tumor. This study was also expected to provide some reference to future development of new method which one's resolution may overstep the traditional optical diffraction limitation.
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