Method for optically detecting biomarkers in a biosensor, comprising: - illuminating a multidielectric substrate of the biosensor at grazing angle with a broadband continuous spectrum; - acquiring, by an optical detector which is one camera or one array of photodetectors, resolved images from at least one sample of the biosensor, the optical detector capturing scattered light from the at least one sample simultaneously with spatial and spectral resolution in a single one resolved image; - performing an image analysis in parallel to the image acquisition, wherein the image analysis comprises: - reading data of the acquired images from storage means; - correcting the read data to reduce inhomogeneities and noise of the acquired images; - generating at least one test pattern which represents a nano-particle shape, - localizing nano-particles in the acquired images by calculating a cross-correlation image between the corrected data and the generated test pattern to obtain a position for each nano-particle; - characterizing each nano-particle individually to obtain an intermediate analysis result which comprises the position and characterization parameters for each nano-particle; - classifying the nano-particles based on the characterization parameters of each nano-particle to obtain classification groups of nano-particles; - counting a number of nano-particles per classification group for each acquired image; - calculating an overall analysis result which comprises at least one statistical value, which is calculated for each biomarker attached to the multidielectric substrate of the biosensor using the number of nano-particles per classification group for all the images acquired from the same sample, wherein the at least one statistical value per sample is correlated with an indication of the presence of a biomarker in the sample. - illuminating a multidielectric substrate of the biosensor at grazing angle with a broadband continuous spectrum; - acquiring, by an optical detector which is one camera or one array of photodetectors, resolved images from at least one sample of the biosensor, the optical detector capturing scattered light from the at least one sample simultaneously with spatial and spectral resolution in a single one resolved image; - performing an image analysis in parallel to the image acquisition, wherein the image analysis comprises: - reading data of the acquired images from storage means; - correcting the read data to reduce inhomogeneities and noise of the acquired images; - generating at least one test pattern which represents a nano-particle shape, - localizing nano-particles in the acquired images by calculating a cross-correlation image between the corrected data and the generated test pattern to obtain a position for each nano-particle; - characterizing each nano-particle individually to obtain an intermediate analysis result which comprises the position and characterization parameters for each nano-particle; - classifying the nano-particles based on the characterization parameters of each nano-particle to obtain classification groups of nano-particles; - counting a number of nano-particles per classification group for each acquired image; - calculating an overall analysis result which comprises at least one statistical value, which is calculated for each biomarker attached to the multidielectric substrate of the biosensor using the number of nano-particles per classification group for all the images acquired from the same sample, wherein the at least one statistical value per sample is correlated with an indication of the presence of a biomarker in the sample. - reading data of the acquired images from storage means; - correcting the read data to reduce inhomogeneities and noise of the acquired images; - generating at least one test pattern which represents a nano-particle shape, - localizing nano-particles in the acquired images by calculating a cross-correlation image between the corrected data and the generated test pattern to obtain a position for each nano-particle; - characterizing each nano-particle individually to obtain an intermediate analysis result which comprises the position and characterization parameters for each nano-particle; - classifying the nano-particles based on the characterization parameters of each nano-particle to obtain classification groups of nano-particles; - counting a number of nano-particles per classification group for each acquired image; - calculating an overall analysis result which comprises at least one statistical value, which is calculated for each biomarker attached to the multidielectric substrate of the biosensor using the number of nano-particles per classification group for all the images acquired from the same sample, wherein the at least one statistical value per sample is correlated with an indication of the presence of a biomarker in the sample.