Optical concentration measuring device

An optical concentration measuring device comprising:

• a substrate;
• a light emitter on a main surface of the substrate and configured to emit light;
• a light receiver on the main surface and configured to receive at least a portion of the light emitted by the light emitter;
• and
• a light guide configured to guide at least a portion of the light emitted by the light emitter to the light receiver, wherein the light guide comprises a first reflector and a second reflector,
• the first reflector and the second reflector are on the main surface of the substrate opposite each other in an overhead view looking directly at the main surface of the substrate,
• the first reflector comprises a main reflective surface and two secondary reflective surfaces, at least a portion of each of which is a quadric surface,
• the second reflector comprises two quadric surfaces,
• light spots occur on the main reflective surface in a lateral view looking from the second reflector to the front of the main reflective surface,
• the first reflector comprises a correction surface configured to correct at least one of the light spots, and
• the correction surface is provided between the main reflective surface and at least one of the two secondary reflective surfaces, and extends in a direction along which the first reflector and the second reflector face each other.