The invention relates to an optical sensor module (1) for a measuring device. Said module comprises at least one optical sensor (2) including a diode laser (3) having a laser cavity for generating a measuring beam, the diode laser being attached to a substrate (12), converging means (5) (such as a lens). During measuring, such converging means (5) converges the measuring beam in an action plane and converges in the laser cavity the measuring beam radiation that has been back-scattered by an object to generate a self-mixing effect and means for measuring the self-mixing effect. Later means comprise a photo diode (4) and an associated signal processing circuitry. According to an essential aspect of the invention, that the diode laser (3) is configured to emit laser radiation of a wavelength for which the substrate (12) being attached to the diode laser (3) is transparent. This configuration leads to an essentially simple (and therefore cheap) sensor module.
