Optical computing device and method for manufacturing optical computing device

An optical computing device comprising:

• a substrate;
• and
• planar light diffraction elements, wherein
• each of the planar light diffraction elements is fixed to the substrate and includes microcells that have respective thicknesses or refractive indices set independently,
• each of the planar light diffraction elements is fixed to the substrate such that an entrance surface of each of the planar light diffraction elements and an exit surface of each of the planar light diffraction elements intersect a main surface of the substrate,
• the optical computing device further comprises an optical element that folds back an optical path of signal light in a plane which intersects the main surface of the substrate, and
• the planar light diffraction elements include:
• a planar light diffraction element directly fixed to the substrate and disposed on one of the optical path which has not been folded back and the optical path which has been folded back;
• and
• a planar light diffraction element indirectly fixed to the substrate via the directly fixed planar light diffraction element and disposed on the other of the optical path which has not been folded back and the optical path which has been folded back.