An observation device for observing a light emission (14, 15) of a sample in a medium with a refractive index n L, the sample being arranged against a surface of a transparent support of refractive index n s, which is greater than n L, the light emission comprising luminous components which have each an amplitude and a phase, oriented toward the support and forming an angle θ with a direction perpendicular to the surface, among which, on the one hand, supercritical luminous components for which the angle θ is strictly greater than a critical angle θ c = arcsin(n L /n s) and, on the other hand, critical or subcritical luminous components for which the angle θ is less than or equal to the critical angle θ c, the observation device being capable of: - capturing at least part of the light emission from a region of interest of the sample and obtaining a captured luminous signal which comprises luminous components originating from the supercritical luminous components of the light emission; - applying filters to the captured luminous signal in order to selectively decrease the amplitude and/or change the phase of certain luminous components of the captured luminous signal to obtain a filtered light signal; and - transforming the filtered luminous signal into an image zone of the region of interest of the sample; the observation device being characterized in that: - it allows producing a modulation of the filtered luminous signal, while luminous components which originate from the critical or subcritical luminous components of the light emission are allowed to pass through, in order to obtain image zones (6a, 6b) of one and same region of interest of the sample, the modulation being effective onto all or some of the luminous components of the captured luminous signal which originate from the supercritical luminous components of the light emission; and - it allows producing at least one useful image zone of the sample by combining the image zones (6a, 6b), the combination evidencing differences between the image zones (6a, 6b) due to the modulation. - capturing at least part of the light emission from a region of interest of the sample and obtaining a captured luminous signal which comprises luminous components originating from the supercritical luminous components of the light emission; - applying filters to the captured luminous signal in order to selectively decrease the amplitude and/or change the phase of certain luminous components of the captured luminous signal to obtain a filtered light signal; and - transforming the filtered luminous signal into an image zone of the region of interest of the sample; - it allows producing a modulation of the filtered luminous signal, while luminous components which originate from the critical or subcritical luminous components of the light emission are allowed to pass through, in order to obtain image zones (6a, 6b) of one and same region of interest of the sample, the modulation being effective onto all or some of the luminous components of the captured luminous signal which originate from the supercritical luminous components of the light emission; and - it allows producing at least one useful image zone of the sample by combining the image zones (6a, 6b), the combination evidencing differences between the image zones (6a, 6b) due to the modulation.