Axio 10

For the optical characterisation of the microprints of the 3D-integrated metasurfaces, we used an optical microscope (Carl-Zeiss AXIO-10) with ×5 (0.13NA), ×10 (0.25NA), ×50 (0.75NA), and ×100 (0.85NA) objective lenses. The different magnifications of the devices at each process step were captured with an incoherent white-light source under transmission mode. The microprint display performance was optimised by modifying the exposure time and contrast of the CCD. Then, the fabricated integrated devices were characterised for hologram projection by the experimental setup shown in Fig. S7. The three laser diodes emitting at 450 nm (Thorlabs CPS450), 532 nm (Thorlabs CPS532), and 633 nm (Thorlabs CPS633S) were exploited to generate R, G, and B channels. The polarizers were used to manipulate the source power to achieve a suitable RGB component ratio due to the polarisation-independent property of the proposed metasurfaces. Then, two dichroic lenses (DMLP567T and DMLP490T) were used to combine the three lasers. The hologram images were projected on a screen and captured by an SLR camera. To characterise the diffraction efficiency for each wavelength, we put an optical power metre in position 1 and position 2 as Fig. S7b shows to measure the transmission power and the diffraction power of the hologram image.

The transmittance spectra under normal incidence were acquired by Olympus microscope (BX-51) equipped with a spectrometer through a 100 × objective (MPlan-FLN, NA = 0.9). An optical microscope (Carl-Zeiss AXIO-10) with ×5 (0.13 NA), ×10 (0.25 NA), ×20 (0.4 NA), ×50 (0.75 NA), and ×100 (0.85 NA) objective lens is used to obtain the transmission optical micrographs with different magnifications.