Refractometric detector for liquid phase chromatograph

A refractometric detector for high performance liquid chromatography comprising:

• a monochromatic light source for emitting a base;
• an optical dividing means for splitting said beam into two parallel beams;
• an optical system having a first mirror and a second mirror disposed perpendicular to the path of said two parallel beams;
• a piezoelectric device which moves said first mirror perpendicularly to its plane;
• a first cuvette containing a reference liquid, and a second cuvette containing a measurement liquid;
• a system having a semi-reflecting surface at 45.degree. for receiving said two beams and reflecting a first part of said beams toward said cuvettes and a second part of said beams to said first mirror, said second part of said two beams being reflected by said first mirror so as to pass through said cuvettes, said second mirror being disposed so as to reflect said first part of said two beams after it passes through said cuvettes toward said semi-reflecting surface along a reverse path, said first and second parts being reflected by said first and second mirrors toward said semi-reflecting surface where said reflected first and second parts are joined together;
• a photodiode detection unit for receiving the joined beams from said semi-reflecting surface and for emitting measurement signals which excite the piezoelectric device, said unit comprising a photodiode means for each beam, said photodiode means sending the emitted signals to a phasemeter which measures the phase shift and the number of cycles of phase shift between the beams.