A micro-pyramid structured thin film with a broad-band infrared antireflection property is designed and fabricated by using the single-point diamond turning (SPDT) technique and combined with nano-imprint lithography (NIL). A structure with dimensions of 10 μm pitch and 5 μm height is transferred from the copper mold to the silicon nitride optical film by using NIL and proportional inductively-coupled plasma (ICP) etching. Reflectance of the micro-optical surface is reduced below 1.0% over the infrared spectral range (800–2500 nm). A finite-difference-time-domain (FDTD) analysis indicates that this micro-structure can localize photons and enhance the absorption inside the micro-pyramid at long wavelengths. As described above, the micro-pyramid array has been integrated in an optical film successfully. Distinguishing from the traditional micro-optical components, considering the effect of refraction and diffraction, it is a valuable and flexible method to take account of the interference effect of optical film.

In this paper, synthetically using refraction, diffraction, and interference effects to achieve free manipulation of the focused optical field, we firstly present a photonic nanojet (PNJ) generated by a micropyramid, which is combined with multilayer thin films. The theory of total internal reflection (TIR) was creatively used to design the base angle of the micropyramid, and the size parameters and material properties of the microstructure were deduced via the expected optical field distribution. The as-designed bilayer micropyramid array was fabricated by using the single-point diamond turning (SPDT) technique, nanoimprint lithography (NIL), and proportional inductively coupled plasma (ICP) etching. After the investigation, the results of optical field measurement were highly consistent with those of the numerical simulation, and they were both within the theoretical calculation range. The bilayer micropyramid array PNJ enhanced the interference effect of incident and scattered fields; thus, the intensity of the focused light field reached 33.8-times that of the initial light, and the range of the focused light field was extended to 10.08$\lambda$. Moreover, the full width at half maximum (FWHM) of the focal spot achieved was 0.6$\lambda$, which was close to the diffraction limit.

Freeform surface optical components have gained increasing attention in recent years, and higher requirements have been put forward for economical and efficient fabrication techniques. Single point diamond turning with fast tool servo is the method to process nonrotational symmetric surface with high quality. However, the surface quality of different areas is not always the same in this way. In this paper, a microlens array is fabricated by fast tool servo cutting. The reason of surface difference is analyzed theoretically, and the Position-Velocity-Time interpolation method is used to improve the surface quality and reduce the difference between different regions. A microlens array consisting of 900 spherical lenslets was machined, the size of each spherical lenslet is 1.08 mm×0.5 mm. The form error of lenslet is about 1.5 um at the edge and 1 um at the center respectively, and the roughness value of Sa are 11 nm and 8.6 nm, the results show that the theory and simulation are correct, and the ability of fast tool servo technology to realize freeform processed with high precision is demonstrated.

The freeform surface quality is limited by the measurement, and form error cannot be convergent via compensation machining. This paper proposed a surface matching measurement strategy based on the least squares principle and iterative precision adjustment to precisely obtain surface form error after manufacturing by single point diamond turning. Through the coordinate transformation of translation and rotation, the measured surface was aligned with theoretical surface at the same coordinate system. The corresponding simulation was carried out to verify the performance of the proposed method, and the simulation results indicated that this method can achieve accurate alignment in a sub-nanometer range. Finally, with XY polynomial freeform surface as the ideal surface, compensation experiments were undertaken. The form error of freeform converged continuously after compensation machining for three times, during which the form accuracy of PV and RMS were down to 335 nm and 34 nm respectively from 1.4 um and 173 nm. The results showed that capability of the proposed compensation method was verified and the form accuracy could be improved effectively.

To realize a multi-channel integrated filter on a single substrate, a new preparation method is proposed in this paper, which was to adjust the thickness of the space layer based on the Fabry–Pérot interferometer theory. Optical thickness adjustment is achieved by integrating multispectral channels on a single substrate that is fabricated combined with coating, nanoimprinting, and single point diamond turning. A multi-channel filter is integrated on a mold and machined once, and three kinds of multi-channel array filter molds are fabricated utilizing fast tool servo turning. The accuracy of each channel is analyzed for the machine accuracy of the mold, which affords the key to this method. Although there exists a slight oscillation error on the surface of each channel, the maximum error is less than 4 nm and the ratio of error and differentials designed is less than 7%. The results indicate that the processing method of the multi-channel filter mold is feasible. As far as this technology is concerned, it provides technical support for mass manufacturing of large-scale multi-channel array filters.