A device and method for observing an object, in particular a biological object, includes a light source able to illuminate a sample, and a screen lying between the light source and the object. The screen includes an aperture, through which propagates the illuminating beam produced by the light source and propagating toward the screen. Under the effect of the illumination, the object emits back-scattered radiation that propagates to the screen, the area of which is preferably larger than 100 cm2. The projection of the back-scattered radiation onto the screen forms an image representative of the back-scattered radiation, called a scattergram. An image sensor allows an image representative of the scattergram formed on the screen to be acquired.