Research And Analysis Of Optical Characteristic On New Type Aerial Lens Shutter

The shutter is an important part of the aerial camera, it has an important impacton the quality and accuracy of image. Denpending on the different location of shutterinstalled in aerial camera, the shutter can be divided into two categories lens shutterand focal plane shutter. The aerial camera with lens shutter has the advantages of eachimage point exposure time at the same time to start and end. Now, it is widely used inaerial mapping camera. In this paper, the digitial aerial camera lens shutter as aresearch object combined with the structure and installed sized requirements of aerialcamera design a new type lens shutter, moreover, analysis the dynamic characteristicsas well as its impact on the optical properities, and then, experimental verification.This papers presents a new type of lens shutter mechanism applied to digitalaerial camera,driving the two blades(rapid blade and slow blade) rotating at one wayhigh speed through clutch and gear train with high speed motor.The slow bladeequivalent to optical gate, rapid blade control exposure time. Changing the speed ofthe high-speed motor can adjust the exposure periods.This structure eliminate shockand other problems caused by the traditional lens shutter reciprocating. The shutterefficiency reaches81%, exposure time range to1/100s～1/1000s, Analysis model ofthe shutter overall structure, establish the lens shutter blades lateral and longitudinalvibration model.Make sure the first four resonant frequencies and the correspondingvibration form.To provide a reference for engineering practice.The new type lens shutter’s high-speed motor drives the blades rotating whichgradually open and close the aperture diaphragm in a work cycle. the optical system isregarded as a spatial frequency of the filter. To establish the relationship between therange of the aperture diaphragm and pupil diffraction theory, the optical transferfunction will be obtained by quadratic Fourier intergral transform method. Analysisthe lens shutter impact on the optical transfer function in the work cycle; According tothe target illumination range and characteristics of CCD device, establish theilluminate function relationship between the image point and object point from the definition of the luminous flux at blade incision open the operture diaphragm to someposition，combined with the characteristic of CCD sensor,determine the shutter effectson the image exposure volume in the exposure time range,By calculating,comparingwith the traditional accuracy provides5.3%; To analysis the radial distortion andcertrifugal distortion of optical system at the blade incision abscured aperturediaphragm to some position, the maximum distortion is up to0.04%in all field ofview of lens,meeting the technical requirements. Therefore, the lens shutter have noeffect on the distortion of the optical system; Analysis of the relationship between theexposure time and image motion with flight attitude angle changes or differentinstallation of camera application homogeneous coordinate transformation methodprovide a theoretical basis for the design of the aerial camera.Rapid lens shutter have higher efficiency、wide exposure time adjustment range、high reliability, can meet the accuracy requirements of aerial mapping camera fully.Analysis of the lens shutter impact on image illumination、optical transfer function、optical distortion and so on, improve the aerial camera shutter theory which have acertain reference value to development of the aerial camera.