Zheyuan Fan

The research of the high precision universal stable reconnaissance platform in near space

The appliance of military was recognized more and more ,It is important that pod can bear the weight of the availability payload achieve the observation to the earth in 20km-100km area and work in the all-weather. The stable platform can load high imaging spectrometer, the thermal infrared imager, the infrared radiometer, the millimeter waves radar, the laser weapon and so on,in order to realize reconnaissance and attacking integrative and warning the long-distant missile. The stabilization accuracy of platform is prior to 20μrad and burden heavy load to the best of ones abilities. It used high precision velocity and acceleration gyroscope to fulfill the stabilization of the platform. Light-weight design by using new composite material and optimizing design. It was adapt to the near space environment better by structure design and simulation analysis.Enhance its basic frequency and sure the rigid of the frame platform .In addition, the structure of platform apply the two-axis and four-frame and use the method of FEA to fulfill the optimum design in order to attain the object of light-weight.In consider to the precision of the platform I establish the math model and make use of the monte carlo method to appraise and analysis the error that affect the precision of the platform. After emulating by the software of the Matlab to verify the results. It is apply the method that link the platform and aerocraft by mounting the no angular displacement shock absorbers on the elevator mechanism. This kind of design insulate the angular vibration and minish the linear vibration to ensure the image quality.

Design of high ratio middle infrared continuous zoom optical system

In recent years, the demand for infrared zoom systems is increasing in proportion with the development of infrared technology and its applications. To meet this demand a variety of zoom lenses have been designed. Infrared cameras operating in the 3-5μm spectral band are used in a wide variety of applications such as targeting, rescue, guidance and surveillance systems as well as other equipment. This paper using cool 320×240 detector with staring focal plane array and secondary imaging, a mid-wave optical system using mechanical-compensated with large-aperture and a zoom range of 10:1 is designed. The Pixel Dimensions of the detector is 30μm, and the wavelength between 3.7μm ~4.8μm.The system adopts negative group variable times and positive group of compensation which can realize 33mm~330mm continuous zoom and FOV =20.61°~2.08° ,it consists of 7 lenses including 3 aspheric surface. The length of the system is 262mm with the reflection mirror multipass optical path. The results show that the modulation transfer function(MTF)are above 0.4 within the whole focal range at spatial frequency of 17 lp/mm, and Root Mean Square (RMS) value of spot diameter were smaller than the Pixel Dimensions. After the image quality being optimized, the narcissus analysis is done and 100% cold shield efficiency is obtained. Finallythe monotonic and smooth Cam curve is given. The curve shows that the imaging plane is stable and the cam is easy to process. The system has advantages of simple structure, high image quality and short zoom path etc.

Design of the segmented primary optical telescope

Following with the “high-resolution upsurge” appeared in many counties in recent few years, it is an inevitable trend to increase the size of the Optical Telescope. However, because of the volume constrains of space-borne astronomical instruments, segmented reflector is thought as the main measure of future astro-physical missions by many scientists. In this paper, a coaxial three-mirror anastigmatic system (TMA) with a segmented primary mirror is modeled in optical software. The optical system, which has 2.4m aperture, 48m focal length and the field-view angle of 0.3°×0.06°, works in the 450nm~900nm wave band. The ‘1+6’ aperture-stiching model is applied. Firstly, the initial structure of the system is inputted to the CODEV, and a certain constraint functions are set, and then the system automatically optimizes. Finally, designing results show that the Modulation Transfer Function (MTF) is really very near to the limit of diffraction. We get a good image quality of the optical system design results.

An automatic multi-spectral infrared sea surface temperature radiometer

Sea surface temperature (SST) is an important parameter in many operational and research activities, ranging from weather forecasting to climate research. A multi-spectral infrared sea surface temperature radiometer is a self-calibrating instrument capable of measuring in situ sea surface temperature to an accuracy of better than 0.1 K. This paper describes an instrument with special design features that double channel radiometer with four spectral band pass of 3µm∼5µm and 8µm∼12µm adapts for autonomous use. The entire instrument infrared optical path is calibrated by viewing two blackbody reference cavities at different temperatures. In this case, the high accuracy of an infrared radiometer is maintained although optical components are moderately contaminated by salt deposition. An newly designed protection shutter that is triggered by a sensitive rain gauge automatically seals the instrument from the external environment in foul weather.

Catadioptric dual-zone Fresnel Condenser with super relative Aperture

The paper introduces a kind of super relative aperture condenser which has the strcuture of spherical Fresnel surface with catadioptric projection optical system, it would improve the condensing capacity and light efficiency substantially. The condenser is composed of two sections with a center and an outer ring, the center region adopted the basic structure of the Fresnel lens with the Fresnel of laplace domain continuous curve transmission type, and the outer structure which achieve light collimating or focusing by total reflection is stepped. The paperstudies the parameter and alforithm of this catadioptric dual-zone Fresnel condenser and gives the surface data of total reflection region. Based on the method of establishing the entity model, we design a set of lens with the relative aperture F=0.3, simulate the condensing ability of the lens by the simulation software, and verify that the lens have a very good effect on focusing.