Microelectronic sensor device with a modulated light source

Abstract

The invention relates to a microelectronic sensor device and a method for making optical examinations at a carrier (11), e.g. for the detection of magnetic particles (1) at a contact surface (12) of the carrier (11) by frustrated total internal reflection (FTIR). A light source (21), particularly a laser light source, with a laser modulator (22) are used for emitting an input light beam (L1) into the carrier (11) which is modulated such that optical interferences with reflections (L1′) of the input light beam (L1) from the entrance window (14) or other components of the carrier (11) are reduced/minimized. This can for example be achieved by a pulsed on/off modulation in which the first relaxation minimum of a currently emitted pulse (PN) coincides in the light source (21) with the first relaxation maximum of a reflected pulse (PN-1′). By reducing the effect of interferences, the setup is less prone to disturbances from dimensional variations that are e.g. induced by thermal extension.

Dependencies are inferred from the claim text.