Road surface meteorological conditions are very important for traffic safety. According to the statistics, the ratio of traffic accidents that occur on icy, wet and dry road surface is about 4.2:1.6:1. A remote road surface meteorological condition sensor based on multi-wavelength light was developed in this paper which could identify the road surface condition including dry, wet, icy and snow, that may be vital for preventing traffic accidents. By using multi-wavelength optical remote sensing technology and near infrared light source, the diffuse reflectance spectrum of road surface can be detected. The four road surface states of dry, wet, ice and snow can be measured with non-contact method, and the thickness of pavement water film can also be measured. Such road sensors were used on G50 highway in Chongqing, China. Experiment results show that the system could meet the requirements well.
Large-aperture telescope with its high spatial resolution and high light gathering capability plays an important role in military, astronomy and other fields. The demand for large aperture imaging telescope is increasingly urgent, the aperture becomes larger and larger, and the splicing main mirror has become the development trend of large-aperture telescope which brings great challenges to the optical processing and testing. This paper proposes phase-diversity phase retrieval technology which can provide a strong basis for the online testing of the future larger diameter astronomical telescope optical system and solve the difficulties in the detection of optical systems in large-aperture telescopes. Therefore, this study has important practical significance and application value in the online testing of the large-aperture telescope optical system.
Measuring optical wave-fronts precisely is a difficult task because detectors directly sense intensity, not phase. The most common method of measuring the phase uses an interferometer that creates an intensity distribution from which the phase of the field can be determined more easily. In order to overcome the wave-front distortion caused by atmosphere turbulence and optical system aberration, the system of wave-front solutions based on the focal plane image information can be used in the optical system in-line detection. The realizations of phase solver technology mainly include phase diversity and phase retrieval. So, this paper mainly explains phase diversity and phase retrieval.