Yuan Hu

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed 《中国光学》的前身是1985年创办的《中国光学与应用光学文摘》，当时是国内光学领域唯一的检索刊物。2008年底《中国光学与应用光学文摘》转型更名为《中国光学与应用光学》期刊，刊载内容突破了文摘的限制，正式成为学术刊物。

The predecessor of China Optics was China Optics and Applied Optics Digest, which was founded in 1985. At that time, it was the only retrieval journal in the field of optics in China. At the end of 2008, China Optics and Applied Optics Digest was renamed 《中国光学》的前身是1985年创办的《中国光学与应用光学文摘》，当时是国内光学领域唯一的检索刊物。2008年底《中国光学与应用光学文摘》转型更名为《中国光学与应用光学》期刊，刊载内容突破了文摘的限制，正式成为学术刊物。

Traditional broadband UV optical designs often have complex structural problems and cannot meet the current requirements of light and miniaturization. In this study, we first design the substrate material of double-layer diffractive optical elements (DOEs) in the 0.23–0.8 μm band, optimize the diffraction efficiency and analyze the effect of the angle of incidence on the diffraction efficiency of double-layer DOEs. Second, we design a refractive lens system and a refractive/diffractive hybrid lens system with double-layer DOEs designed for a wide UV wavelength range of 0.23–0.8 μm, a half field of view of 15 mm, an objective aperture of 0.1 and a magnification of 1. The refractive/diffractive hybrid lens system designed with seven lenses produces a higher image quality than the refractive lens system. The novel design is an effective solution to the problem of the low transmission rate of traditional UV refractive lens systems.

Aiming at the problem that diffraction effect of digital micro-mirror device (DMD) has serious influence on system imaging, the stray light generated by DMD device was studied. Firstly, based on the rigorous coupled wave theory, the DMD diffraction model was constructed and the effects of different bands and incident angles on its diffraction efficiency were analyzed. It was concluded that the diffraction effect of DMD was more obvious in the long-wave infrared band, and the diffraction effect of DMD was more significant with the increase of incident angle. Secondly, the generation methods of diffracted stray light of DMD in the projection system was analyzed. By changing the number of F in the system, the incident angle was controlled, and then the energy proportion of stray light generated by the diffraction effect of DMD was calculated. Finally, the curve of the optical system with different number of F at different wavelengths along with the diffraction effect was obtained. The results show that the larger the F number, the smaller the influence of DMD diffraction effect on stray light.

Terahertz time-domain spectroscopy (THz-TDS) is an effective coherent detection technique for deeply understanding the structures and functions of biomolecules. However, generally not full information in the whole THz range can be obtained due to the limited detection bandwidth (usually less than 5 THz) of the traditional THz-TDS systems. In this paper, effective THz absorption spectra in 0.5–10 THz range of five typical nucleobases of DNA/RNA are characterized with a super broadband THz detection technique, called the air-biased- coherent-detection (THz-ABCD) technique. Few unexpected characteristic absorption peaks appeared in the low-frequency region and meanwhile a series of anticipated characteristic absorption peaks are found in the high-frequency region. The fingerprint spectra of these nucleobases are helpful for further analysis on the vibration and twisting behavior of hydrogen bonds, van der Waals and electrostatic forces etc. between and within DNA/RNA biomolecules.

For a long communication distance, the divergence angle of laser transmission by a space laser communication system must be sufficiently narrow to solve the energy problem. However, it needs to be magnified during the ground test before the satellite launches. This way, the two communication terminals can be constantly in the coverage of each other’s laser beam even when the tracking accuracy decreases because of the atmosphere. This Letter presents methods to magnify the divergence angle for laser transmission. The diffraction intensity distributions with different methods and their influence on communication are discussed. We provide the optimal scheme in the ground test of a certain space laser communication. The result represents the accumulated experience for the space laser communication ground test.