METHOD OF MANUFACTURING A DIFFRACTIVE OPTICAL ELEMENT AND DIFFRACTIVE OPTICAL ELEMENT

A method of manufacturing a diffractive optical element effective at an operating wavelength, comprising the following steps: providing a first substrate (SUB1) made of a first substrate material; depositing a layer of a first material on a free surface of the first substrate (SUB1) or one a free surface of an auxiliary layer (AL) formed on the free surface of the first substrate; patterning the layer of the first material to generate a patterned structure comprising a plurality of ridges of the first material and intermediate spaces between the ridges; filling the intermediate spaces with a second material (M2) differing from the first material (M1) to form a patterned layer comprising adjacent portions alternately consisting of the first material (M1) and the second material (M2) to form a multilayer unit (MU) comprising the first substrate (SUB1) and the patterned layer (PL) on the first substrate, the multilayer unit comprising a free surface opposite to the first substrate; providing a second substrate (SUB2) made of a second substrate material (MS2), the second substrate (SUB2) comprising a free surface (FS2) prepared as a contact surface; bonding the multilayer unit (MU) to the free surface (FS2) of the second substrate (SUB2) so that the free surface of the multilayer unit is adjacent to the free surface (FS2) of the second substrate. The diffractive optical element may be designed as a computer generated hologram for use in an interferometric measuring device for interferometrically measuring a shape of a surface of a test object.