An optical vital signs sensor comprises a light source (110) having alight unit (111, 112) generating light which is directed towards a skin (1000) of a user, at least one photo detector unit (120) having a plurality of photo diodes (121-12n) detecting light from the skin (1000), and an adjusting unit (140, 150) configured to adjust an effective distance which the light travels between the light unit (111, 112) and the photo diode (12-12n).
