The present application is directed to a device for inspecting a keratinous surface of a user, preferably a hair sample, comprising a housing in which an image sensor is arranged to receive measurement light emitted from a measuring area configured to accommodate the keratinous surface, through a measurement window in a front wall of the housing, over a corresponding imaging light path, the device being further equipped with an illumination ring arranged in the housing rear of the measurement window around the imaging light path, said illumination ring having two opposed partially peripheral illumination portions separated by two opposed complementary partially peripheral non-illuminating portions, the illuminating portions being further configured to illuminate the measuring area through the measurement window over a illumination light path, said illumination light path having an angle of incidence comprised between 30 to 60°, preferably about 45°
