The invention provides a system (1) comprising a sensor (100) for measuring a skin parameter, the sensor (100) comprising (i) a plurality of spatially separated light sources (110) configured to provide light source light (111), and (ii) a detector (120) configured at a first distance (d1) from each of the light sources (110), wherein the first distance (d1) is selected from the range of 5-80 mm, wherein the sensor (100) is configured to provide the light source light (111) with optical axes (OL) under an angle (α) relative to an optical axis (O2) of the detector (120) selected from the range of 10-80°, wherein the sensor (100) comprises at least three light sources (110), wherein the light sources (110) are configured to provide unpolarized light source light (111), wherein the sensor (100) further comprises (iii) a sensor opening (107) downstream of the light sources (110) and upstream of the detector (120) for propagation of the light source light (111) out of the sensor (100) and for entrance of reflected sensor light (111) into the sensor (100), and (iv) a sensor window (150), of a material (151) transmissive for the light source light (111), configured downstream of the light sources (110), configured upstream of the sensor opening (107), and configured upstream of the detector (120) with a second distance (d2) to the sensor opening (107) of at least 3 mm.