Waveguide and associated automotive-vehicle-borne spectrometer

A vehicle-borne spectrometer for measuring a spectrum of a light beam in a pre-determined wavelength range, the spectrum being generated by a fluid to be analyzed, said spectrometer comprising:

• at least one light source defining an orthogonal coordinate system;
• a waveguide configured to shape an incident optical beam emitted by the at least one light source, and divide said optical beam into a measurement beam and a reference beam;
• a measurement cell, comprising at least two walls comprising the fluid to be analyzed, wherein a flow direction of the fluid into the measurement cell defines a longitudinal axis Z, a transverse axis Y that is normal to said at least two walls, and an axis X that is orthogonal to both the axis Z and the axis Y;
• a measurement detector, placed on an optical pathway taken by the measurement optical beam, encountering the measurement cell;
• and
• a reference detector, placed on an optical pathway taken by the reference optical beam, not encountering the measurement cell,
• characterized in that the waveguide consists of a single unit, the single unit comprising:
• a first volume, which has a thickness (e) along the axis X, for forming and separating the incident beam emitted by the light source into two substantially parallel and identical beams, said light source being pressed against a first end of the first volume;
• a second volume having a thickness equal to that of the first volume for guiding the measurement beam towards the measurement detector, said second volume being pressed, via a free end, against a first wall of the measurement cell;
• and
• a third volume having a thickness equal to that of the first volume for guiding the reference beam towards the measurement detector, said third volume being pressed, via a free end, against the reference detector.