With the continuous development of new infrared optoelectronic detection methods, the computational imaging based on encoding mask has received attention due to its ability to obtain spatiotemporal synchronous multidimensional information including intensity, spectrum, and polarization. However, the research results of this technology in the infrared band are relatively scarce at present. As is well known, one of the challenges in infrared computing imaging technology is information modulation and calibration. Only by obtaining a multidimensional information calibration dictionary can subsequent system integration and information recovery be completed. This paper focuses on multi-dimensional information modulation and high-precision calibration technology, and simultaneously conducts research on optimization schemes for multi-dimensional information calibration. Finally, performance indicators are verified using speckle field autocorrelation algorithm. The simulation results indicate that the multi-dimensional information modulation and calibration technology adopted in this paper can effectively obtain the multi-dimensional information calibration dictionary, laying the foundation for the subsequent integration of infrared computing imaging systems.
Traditional mid-infrared optical devices are characterized by complex structures, large volumes, and high prices, which impede the advancement of future multidimensional, multifunctional, and miniaturized integration. However, metasurfaces comprising planar and ultra-thin nanostructures have emerged as a promising alternative. By manipulating the interaction between light and materials at subwavelength scales, metasurfaces exhibit remarkable control over optical fields and offer multifunctional capabilities. Consequently, they provide new avenues for integrating infrared systems in a miniaturized form. In this paper, an efficient metalens based on Pancharatnam-Berry (PB) phase working in the mid-infrared range(3.7μm-4.8μm) is proposed and numerically demonstrated. The proposed metalens enables precise control of incident light phase, thereby converge the incident light into two focal spots within spectral-band ranges: 3.7μm-4.0μm (with a focal length of 150μm) and 4.5μm-4.8μm (with a focal length of 250μm). The bifocal metalens is space division multiplexing designed using alternately arranged a-Si nanobricks, facilitating a high polarization conversion efficiency exceeding 80% and achieving achromatic behavior within the two spectral-band ranges. This work demonstrates the potential application of metalens for addressing complex tasks in infrared optical detection.
Thermal radiation of the normal temperature optical system coinciding with the target radiation spectrum is the main background noise source for long-distance infrared detection of weak targets. It will reduce the detection sensitivity and detection distance of the system and increase the difficulty of target detection and recognition. Reducing the temperature of the optical system is the most direct and effective way to reduce its own radiation, which can reduce the background noise of the system. The cooling time and temperature characteristics of the lens under different optical-mechanical structures are simulated. The simulation results show that the cryogenic lens assembly with copper material optical-mechanical structure has a heat leakage of 0.2W at 180K, and the temperature difference between the center points of the two lenses is 0.8K. A miniaturized ultra-high frequency pulse tube cryocooler is used as a cold source to cool the lens assembly of 30 g optical-mechanical thermal mass. The temperature characteristics of the lens under different input power of the cryocooler are tested. By optimizing the temperature control strategy, the lens temperature can be stabilized at 180 K in 15 minutes, the temperature fluctuation is ± 0.2K, and the temperature difference between the two lenses is less than 1K, which is a useful exploration for the infrared detection system directly integrated with cryogenic optics.
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