Device for the Direct Optical Recording of Skin Prints

A device for direct optical recording of skin prints, the device comprising:

• a layer body comprising a placement surface formed by a cover layer of the layer body;
• a sensor layer having light-sensitive elements arranged in a sensor grid and transparent areas;
• a light source unit formed as a light guide layer and arranged below the sensor layer;
• the light guide layer having at least one LED for coupling in of light at a narrow side and being provided with light out-coupling structures permitting directed coupling out of light from the light guide layer at a defined angle based on an inclination angle of the light out-coupling structures and on differences in refractive indices between the neighboring layers of the light guide layer up to the cover layer;
• the light out-coupling structures having an inclination angle coupling light out from the light guide layer at the defined angle in such a manner that the out-coupled light, after having passed through all layers up to the cover layer, undergoes a total internal reflection (TIR) at an air interface of the placement surface and has a divergence angle range of ≤+/−15°;
• and
• a first adhesion layer between the cover layer and the sensor layer and a second adhesion layer between the sensor layer and the light guide layer, wherein the second adhesion layer has a refractive index which is at least 1% lower and at most 30% lower than refractive indices of the light guide layer and of the sensor layer which are between 1.45 and 1.8, and wherein the first adhesion layer has a refractive index which is at least as high as that of the second adhesion layer.