A device for analyzing the surface structure of an object, the device comprising a touchable Lambertian light diffusing surface that covers a cavity containing a light source and an image sensor. The image detector senses the contact of the outer Lambertian surface of the device by a contacting object, for example a finger-tip, by means of light from the light source reflecting back to the image detector. At the same time, ambient light from objects external to the device is diffusely scattered by the Lambertian surface as it enters the cavity and does not affect the ability of the image detector to clearly determine the surface structure of the contacting object. Thus, for example, the surface contours of a fingerprint may be determined with a high signal-to-noise ratio.