Research On Optical Adjustment Detection Method And System Of Binocular Low-light Night Vision Device

Binocular low-light level(LLL)night vision device is a common instrument used for observing at night.As it is directly worn over eyes,its poor properties may be threats to user's security and health.At present,the instruments used for adjusting and testing the LLL night vision device have some problems,such as large size,single function.They are hard to transport and the measurement results are not objective.So,it is necessary to do research on comprehensive portable equipment used for the calibration and automatic measurement of LLL night vision device.In this thesis,the testing methods of parallelism of optical axes,image magnification,the difference of magnification,image inclining and resolution are analyzed.The index which the equipment should achieve is determined according to standards related to LLL night vision device.The general scheme of the equipment is designed.Based on the index requirement and the general scheme,the property parameters of the collimator lens,pretelescope lens,cross line reticle and resolution pattern,image acquisition device,illumination and computer hardware are determined.The design and selection of these devices is done.In order to automatically test the parallelism of optical axes,image magnification,the difference of magnification and image inclining,the centers of three cross lines should be obtained.By counting the pixel number in each row and column and calculating statistics to obtain the peak position,the range of every cross line's center can be found.By using gray weighted centroid algorithm,the centers of cross lines are obtained.In order to automatically test the resolution,the location algorithm based on Hough transform and morphological operation is used to improve the positioning accuracy.Multiple lines of pixels on the resolution pattern which are vertical to pattern lines are chosen to calculate the contrast.The contrast is compared with the threshold to determine whether the resolution pattern can be recognized.The automatic detection software is programmed using Visual C++ language,realizing the functions of testing,saving and searching.The night vision device is protected by using the software to control the electric circuit.During the process of equipment alignment and function verification,experiments about parallax correction?calibration of measured function are done.The well-calibrated equipment is used to measure a LLL night vision device.The measuring results are compared with the measuring results of traditional instrument.The comparisons show that the calibration function of the calibration-measurement equipment of binocular LLL night vision device works well,and the measurement precision of the equipment meets the requirements.