Optical component (100; 500; 600A; 600B) for an attenuated total reflection multispectral imaging device, characterised in that it comprises a support substrate (110; 510) and at least two planar waveguides (120 1 , 120 2 , 120 3 ; 520 1 , 520 2 , 520 3 ), and in that : - each of the planar waveguides (120 1 , 120 2 , 120 3 ; 520 1 , 520 2 , 520 3 ) extends in a respective plane, with said respective planes parallel to each other and parallel to a plane of the optical component; - the planar waveguides (120 1 , 120 2 , 120 3 ; 520 1 , 520 2 , 520 3 ) and the support substrate (110; 510) are superimposed together along an axis orthogonal to the plane of the optical component, with the support substrate which covers the planar waveguides; - each of the planar waveguides comprises at least one diffraction grating (130 1 , 130 2 , 130 3 ), to extract light out of said planar waveguide; - at least two of the planar waveguides have their respective diffraction gratings (130 1 , 130 2 , 130 3 ) which have values of the average pattern distribution pitch which are distinct from each other; - the support substrate (110; 510) comprises, on one side opposite the planar waveguides (120 1 , 120 2 , 120 3 ; 520 1 , 520 2 , 520 3 ), a face configured to form an exchange interface with a sample and to be incident to the light extracted from the planar waveguides (120 1 , 120 2 , 120 3 ; 520 1 , 520 2 , 520 3 ); and - an exit face (113; 513; 613A; 613B) of the optical component (100; 500; 600A; 600B) corresponds to a lateral face of the support substrate (110; 510) arranged so that the light extracted from the planar waveguides (120 1 , 120 2 , 120 3 ; 520 1 , 520 2 , 520 3 ) and reflected by total reflection in the support substrate (110; 510) at the face configured to form the exchange interface emerges from the optical component (100; 500; 600A; 600B) through this exit face (113; 513; 613A; 613B). - each of the planar waveguides (120 1 , 120 2 , 120 3 ; 520 1 , 520 2 , 520 3 ) extends in a respective plane, with said respective planes parallel to each other and parallel to a plane of the optical component; - the planar waveguides (120 1 , 120 2 , 120 3 ; 520 1 , 520 2 , 520 3 ) and the support substrate (110; 510) are superimposed together along an axis orthogonal to the plane of the optical component, with the support substrate which covers the planar waveguides; - each of the planar waveguides comprises at least one diffraction grating (130 1 , 130 2 , 130 3 ), to extract light out of said planar waveguide; - at least two of the planar waveguides have their respective diffraction gratings (130 1 , 130 2 , 130 3 ) which have values of the average pattern distribution pitch which are distinct from each other; - the support substrate (110; 510) comprises, on one side opposite the planar waveguides (120 1 , 120 2 , 120 3 ; 520 1 , 520 2 , 520 3 ), a face configured to form an exchange interface with a sample and to be incident to the light extracted from the planar waveguides (120 1 , 120 2 , 120 3 ; 520 1 , 520 2 , 520 3 ); and - an exit face (113; 513; 613A; 613B) of the optical component (100; 500; 600A; 600B) corresponds to a lateral face of the support substrate (110; 510) arranged so that the light extracted from the planar waveguides (120 1 , 120 2 , 120 3 ; 520 1 , 520 2 , 520 3 ) and reflected by total reflection in the support substrate (110; 510) at the face configured to form the exchange interface emerges from the optical component (100; 500; 600A; 600B) through this exit face (113; 513; 613A; 613B). <EOS>