Imaging Performance Of Optical Systems Research Articles

Computational imaging with randomness

AbstractImaging is a longstanding research topic in optics and photonics and is an important tool for a wide range of scientific and engineering fields. Computational imaging is a powerful framework for designing innovative imaging systems by incorporating signal processing into optics. Conventional approaches involve individually designed optical and signal processing systems, which unnecessarily increased costs. Computational imaging, on the other hand, enhances the imaging performance of optical systems, visualizes invisible targets, and minimizes optical hardware. Digital holography and computer-generated holography are the roots of this field. Recent advances in information science, such as deep learning, and increasing computational power have rapidly driven computational imaging and have resulted in the reinvention these imaging technologies. In this paper, I survey recent research topics in computational imaging, where optical randomness is key. Imaging through scattering media, non-interferometric quantitative phase imaging, and real-time computer-generated holography are representative examples. These recent optical sensing and control technologies will serve as the foundations of next-generation imaging systems in various fields, such as biomedicine, security, and astronomy.

Quantitative evaluation of refractive index inhomogeneity and its effect on the imaging performance of high-precision injection molded optical lens

High-precision injection molded plastic lenses are gradually substituting the application of glass lenses in advanced imaging and illumination optical systems for their high efficiency and reproducibility. Despite the surface deviation of the plastic lenses having been reduced to micron dimension, the imaging performance of the systems could not be guaranteed. More and more investigations demonstrated that the inhomogeneity of refractive index (RI) variation of plastic lenses was much higher than that of glass lenses. However, the effect of refractive index inhomogeneity on imaging performance is still not well understood, and is not fully considered in the optical design and injection molding process. Thus, an integrated analytical approach was proposed to quantitatively evaluate the inhomogeneity of the refractive index and to reveal its effect on the imaging performance of the optical system. It was found that the inhomogeneity reached 3.44 × 10−3, which was three orders of magnitude higher than that of the glass blank (2.80 × 10−6). Both the magnitude and distribution of refractive index variation significantly degraded the quality and homogeneity of the modulation transfer function (MTF) and spot diagram, from calculated imaging performance considering the inhomogeneity. The maximum MTF was reduced by 60 % compared with the design value. Comparative investigation also demonstrated that refractive index inhomogeneity had an equivalent effect on the imaging performance in comparison with the micron order surface deviation. Reducing the degradation of refractive index inhomogeneity provides an efficient way to improve the imaging performance of advanced optical systems.

THIẾT KẾ HỆ THỐNG QUANG HỌC HOẠT ĐỘNG TRONG HAI VÙNG PHỔ NHÌN THẤY VÀ HỒNG NGOẠI BƯỚC SÓNG DÀI

This article demonstrates how to select an appropriate combination of materials based on the requirement of simultaneously chromatic aberration reduction in two spectral bands: visible and long-wave infrared. Then proceed to design the optical system for the objective of the camera operating in both of the above mentioned spectral regions by using an aspherical/diffractive surface to improve the imaging performance of optical system. The designed optical system has a simple structure, consisting of only 3 elements, and high image quality, modulation transfer function (MTF) at Nyquist frequency is higher than 0.28. It is suitable for imaging system in unmanned aerial vehicle.

Integrated Optomechanical-Thermal Analysis of Aeronautic Camera Window

In order to improve the imaging performance of aeronautic camera optical system, an analysis of the influence of window glass optical performance caused by the flying environment was conducted. Based on the theory of aerodynamics, the Mach number and Reynolds number were calculated. The flying environment of window was gotten. The heat-transfer model of the camera was established. The heat flow on surface of window was calculated. The temperature distribution was simulated with the Workbench Software. Combined with the force on the window, the surface deformation of the window glass was calculated under the thermal-force coupling conditions. Zernike polynomial was used to fit the surface deformation of window glass with the Sigfit Software. Putting the Zernike polynomial coefficients into optical software, taking MTF as assessment indexes, the influence of deformation of window glass on the imaging performance of optical system was analyzed. The results show that the optical window meets optical performance requirements.